Safety Assessment of Trimoniums as Used in Cosmetics

Straight and branched chain alkyl trimonium ingredients

Laurtrimonium bromide was reported to be used for the separation and purification of DNA fragments. ³⁵

A commercial product containing cetrimonium bromide (and other quaternary ammonium salts) was reported to be used as a topical antiseptic. ¹

Alkanol trimonium ingredients

Choline chloride was reported to be considered generally recognized as safe (GRAS) as a nutrient by the FDA. ³⁶

Choline and carnitine are reported to be used as dietary supplements.^37,38

Straight and branched chain alkyl trimonium ingredients

The original safety assessment reported that orally administered cetrimonium bromide (0.8 mg/kg) was poorly absorbed by the intestinal tract of rats. ¹ Greater than 90% of the cetrimonium bromide was recovered 3 days after oral administration in the feces.

Alkanol trimonium ingredients

Choline consumed in the diet is important to the structural integrity of cell membranes, methylation metabolism, cholinergic neurotransmission, transmembrane signaling, and lipid and cholesterol transport and metabolism. ²⁰ Choline was obligatory to human cell survival. It was available in the diet as free choline and as phosphatidylcholines, such as lecithin in egg yolks, vegetables, and animal fat.

Choline consumed in the diet by mammals was reported to be absorbed from the lumen of the small intestine using transporter proteins in the enterocyte.^39–42 In the gut, choline can be liberated from phosphatidylcholine by pancreatic enzymes. ⁴³ Some metabolism by bacteria to form betaine and methylamines was reported to be required before choline can be absorbed from the gut. ⁴⁴ The free choline enters the portal circulation of the liver, whereas phosphatidylcholine may enter via lymph in chylomicrons. ⁴⁵

Choline functions as a precursor for acetylcholine, phospholipids, and the methyl donor betaine.^46,47

All tissues accumulate choline by diffusion and mediated transport. ⁴⁸ A specific carrier mechanism transports free choline across the blood–brain barrier at a rate that was reported to be proportional to the serum choline concentration. In the neonates, this choline transporter has a high capacity. ⁴⁹ The rate at which the liver takes up choline was reported to be sufficient to explain the rapid disappearance of choline injected systemically. ⁵⁰ The kidney also accumulates choline. ⁵¹ Some choline from the kidney appears in the urine unchanged but most was reported to be oxidized within the kidney to form betaine. ⁵² A significant portion of choline was reported to be oxidized to form betaine in the liver and kidney.^53,54

Choline was reported to be phosphorylated, converted to cytidine diphosphocholine, and then converted to phosphatidylcholine in the predominant pathway for phosphatidylcholine biosynthesis.^55,56 In an alternative pathway, phosphatidylethanolamine was reported to be sequentially methylated to form phosphatidylcholine by the enzyme phosphatidylethanolamine-N-methyltransferase using S-adenosylmethionine as the methyl donor.^57,58 This was reported to be the major, and possibly only, pathway for synthesis of the choline moiety in adult mammals. It was reported to be most active in the liver but has been identified in many other tissues.^59–61 There are no estimates available as to the relative extent of choline obtained from cell turnover.

Acetyl l-carnitine was reported to be maintained in the human body by dietary intake, some synthesis, and efficient renal reabsorption. ⁶² Dietary carnitine was reported to be absorbed by active and passive transfer in the intestine. Food provides 54% to 87% of carnitine. The kidneys are an important regulator of carnitine homeostasis. At normal levels, reabsorption of carnitine in the kidneys was reported to be efficient (90%-99% of filtered load). Renal reabsorbtion decreases when the circulating carnitine load increases. Circulating carnitine was reported to be distributing between large and slow turnover (ie, muscle) and small and rapid turnover (ie, liver, kidney, and other tissues). At normal dietary intake levels, whole-body turnover in humans was reported to be 38 to 119 h.

Polymeric trimonium ingredients

No information was discovered on the oral absorption, distribution, metabolism, and excretion of the trimonium polymers.

Straight and branched chain alkyl trimonium ingredients

The percutaneous absorptions of [ ¹⁴ C] laurtrimonium bromide (0.5%) through nonoccluded rat skin and the resulting blood levels were studied. ⁴ Percutaneous absorption was low. Application in a cream hair-rinse preparation under user conditions (10 cm² area, lathered for 3 minutes, left for 15 minutes, rinsed, dabbed dry) resulted in the absorption of ∼0.1% of the administered radioactivity in 48 hours. No measurable radioactivity was present in the blood. Application of the surfactant at a higher concentration (3%) in an aqueous solution resulted in a higher absorption of 0.6% in 72 hours. Some radioactivity, equivalent to < 100 ng of unchanged [ ¹⁴ C] laurtrimonium bromide, was measured in the blood after administration to the skin without subsequent rinsing.

The original safety assessment reported that a percutaneous absorption study showed that 0.59% of 1% cetrimonium bromide penetrated rat skin after 15 minutes; 0.93% of 0.5% cetrimonium bromide in a hair rinse formulation penetrated after 5 min of exposure followed by rinsing; and 3.15% of 3.0% cetrimonium bromide in water penetrated after 15 minutes of exposure. ¹

Dehyquart A-CA (25% cetrimonium chloride in a 3.5% emulsion; 25 mg/cm² 100 mg on 4 cm²) was applied to the dermatomed, thawed, full thickness skin (1000 µm; n = 6) of the back and flank of castrated male pigs in a diffusion chamber for 30 minutes. ⁶³ The test substance was then washed off and the receptor fluid sampled up to 72 hours. At 72 hours, the amount of test substance was measured by high-pressure liquid chromatography/electron spectroscopic imaging/mass spectrometry (HPLC/ESI/MS) and was below detection limits in the receptor fluid, 0.7 ± 0.6% in the stratum corneum, 0.3% ± 0.3% in the dermis, 1.0% ± 0.9% total in the skin, and 90.2% ± 4.5% in the rinsing solution. The authors concluded that cetrimonium chloride may not be systemically available by a dermal route.

Alkanol trimonium ingredients

Full thickness human skin (n = 12) was used in Franz cells to test the penetration of radiolabeled choline chloride (5%) with and without occlusion. ⁶⁴ Samples were taken up to 24 hours. At 24 hours, 0.457 µg/cm² choline had penetrated into the receptor chamber for occluded skin and 0.383 µg/cm² for unoccluded skin, 0.127% and 0.110% of the applied dose, respectively. There was no statistical difference in these results. Total absorption (epidermis, dermis, and receptor fluid) was 7.42 µg/cm² (1.9%) and 13.86 µg/cm² (3.43%) for occluded and unoccluded skin. Most of the choline remained in the epidermis and dermis. The authors concluded that choline chloride has a low potential for percutaneous absorption.

Polymeric trimonium ingredients

Less than 1.5% of polyquaternium-10 (100%; 4.0 mL/kg) penetrated the skin of Fisher 344 rats (n = 12) over 24 h. ⁷

Straight and branched chain alkyl trimonium ingredients

In the original safety assessment, cetrimonium bromide was rapidly excreted in the urine and feces of rats after subcutaneous and intervenous administration. Greater than 90% of the cetrimonium bromide was recovered 2 days after subcutaneous administration. There were only traces of cetrimonium bromide in the body 24 hours after intravenous (iv) injection. ¹

Alkanol trimonium ingredients

[ ¹⁴ C]Carnitine (100 µCi/kg) was injected intraperitoneally (ip) into pregnant CD-1 mice on day 17 of pregnancy. ⁶⁵ At 1, 2, 3, and 6 h after the injection, the mice were killed and a full body x-ray was performed. The highest concentrations of carnitine were found in the liver, placenta, kidney, myocardium and choroid plexus. No carnitine was observed in the brains of the fetuses or the dam. There was carnitine in the fetuses but less than that in the dam; the distribution was similar and increased with time. Carnitine crossed the placental barrier.

Straight and branched chain alkyl trimonium ingredients

Cetrimonium bromide (in a mineral oil-water emulsion) enhanced penetration of phenylazoaniline (pH 7.0), benzocaine (pH 7.0), and benzoic acid (pH 7.0) up to 0.5% in a Franz cell using dialysis or hydrophobic polydimethylsiloxane membrane membranes. ⁶⁷ Concentrations above 0.5% were less effective until penetration was inhibited at ≥1.0%. Cetrimonium bromide inhibited penetration of benzoic acid (pH 3.0) and the penetration of phenol (pH 7.0) was not affected.

Alkanol trimonium ingredients

Palmitoyl carnitine (0.2 mmol/L) was reported to enhance the penetration of Lucifer yellow and Ruthenium red across Caco-2 monolayers by ∼10-fold and ∼20-fold, respectively. ⁶⁸ Acetyl carnitine (with a shorter alkyl chain) did not enhance penetration using Caco-2 cell monolayers. Palmitoyl carnitine did not enhance the penetration of PEG 4000. The authors suggest that since there was no damage to the epithelium observed and there was rapid reversal of the effects with the removal of palmitoyl carnitine, the penetration enhancement was not due to cell lysis.

Nasal administration of palmitoyl carnitine (20%) simultaneously with human growth hormone increased the peak penetration by 260%, area under the absorption curve by 64%, and bioavailability by 12.2% in male Wistar rats (n = 5). ⁶⁹

Straight and branched chain alkyl trimonium ingredients

The lethal concentration of laurtrimonium chloride for rat primary hepatocytes was >0.048 µL/ mL. ⁷⁰

Human K562 erythroleukemic cells were incubated with cetrimonium bromide (0.1 to 10 μmol/L) for 5 days (n = 3). ⁷¹ Cell growth decreased in a dose-dependent manner compared to controls. When in a liposome suspension or micellar solution, cell growth decreased in a dose-dependent manner; the IC₅₀s (concentration that inhibits 50% of growth) were 0.88 and 0.62 mmol/L, respectively.

Human keratinocytes from foreskins were incubated in cetrimonium chloride for 3 days. ⁷² Metabolism was then measured using tetrazolium dye. Concentrations >3 µg/mL completely inhibited dye reduction. At 0.8 µg/mL, there was no inhibition of dye reduction. Concentrations between 0.01 and 0.1 µg/mL enhanced dye reduction. Measurement of DNA content revealed that at these low concentrations, cetrimonium chloride had a stimulatory effect on cell proliferation.

The minimum inhibitory concentration (MIC) of cetrimonium bromide was 16 mg/mL for Escherichia coli and 128 µg/mL for Pseudomonas aeruginosa. ⁷³ The authors suggested that cetrimonium bromide was able to disrupt membrane function of gram-negative bacteria. In addition to and simultaneously with this disruption, this ingredient can also chelate K⁺ ions from the bathing medium.

The EC₅₀ (effective concentration) values for cetrimonium bromide and laurtrimonium bromide for Salmonella typhimurium were 4.88 ± 0.08 × 10⁻⁶ mol/L and 75.00 ± 3.90 × 10⁻⁶ mol/L, respectively. ⁷⁴ The MICs were 1.65 × 10⁻⁴ and 4.86 × 10⁻⁴ M, respectively.

Straight and branched chain alkyl trimonium ingredients

In 2 separate studies, the oral LD₅₀ of laurtrimonium chloride in Sprague-Dawley CD rats (n = 5) was 490 mg/kg (confidence interval [CI] 420 to 570 mg/kg) and 560 mg/kg (500 to 630 mg/kg). ⁷⁰

The original safety assessment reported that the oral LD₅₀ of 40% w/v cetrimonium chloride was 1000 mg/kg for rats. ¹

The LD₅₀ for cetrimonium chloride ranged from ∼1550 to 2970 mg/kg for rats in unpublished studies of acute oral toxicity that were reported by the European Union’s Committee on Consumer Products (SCCP). ⁶³ The LD₅₀ for steartrimonium chloride was ∼700 mg/kg. A mixture of cetrimonium and steartrimonium chloride had an LD₅₀ of >2000 mg/kg in rats.

A material safety data sheet (MSDS) reported the LD₅₀ for behentrimonium chloride for rats to be >4 g/kg. No further information was provided. ¹³

The combined LD₅₀ for tallowtrimonium chloride for Sprague-Dawley CFY rats was 1260 (CI 1061-1496) mg/kg, 1289 (CI 1145-1444) mg/kg for males, and between 1000 and 2000 mg/kg for females. ⁷⁰ In Swiss-Webster mice, the oral LD₅₀ of cetrimonium chloride was between 400 and 600 mg/kg. ⁷⁰ The oral LD₅₀ of steartrimonium chloride was 633 mg/kg for male mice and 536 mg/kg for female mice.

Alkanol trimonium ingredients

The oral LD₅₀ was reported to be between 3150 and ≥ 5000 mg/kg for choline chloride in rats. ²⁰ Clinical signs after ingestion were restlessness, increased respiration, hypoactivity, convulsions, ruffled coat, staggered gait, and dyspnea. There was some diarrhea. At necropsy, 3 of 10 rats had inflamed lungs.

The oral LD₅₀ of choline chloride in mice was reported to be in the range of 3900 and 6000 mg/kg. ²⁰

The oral LD₅₀ of choline chloride was 340 mg/kg for ICR mice and >400 mg/kg for Sprague-Dawley rats. ⁷⁵

The oral LD₅₀ of choline HCl in Swiss CD-1 holoxenic mice was 3900 mg/kg. ⁷⁶ All animals showed salivation, lacrimation, respiratory depression, and convulsions prior to death. The maximum cholinergic effects were observed within the first hour, and all the animals died during the first 24 hours of observation. The LD₀ was 2000 mg/kg.

Polymeric trimonium ingredients

The oral LD₅₀ of polyquaternium-28 for rats was reported to be >5 g/kg. ¹⁸

Polyquaternium-47 (<30% aqueous; 5000 mg/kg) orally administered to Wistar rats caused no mortality, clinical signs, or body weight changes. ⁷⁷

The oral LD₅₀ of polyquaternium-10 was >16 g/kg for rats. ⁷

Straight and branched chain alkyl trimonium ingredients

In an acute dermal test of cetrimonium chloride (100%; 4.3 mL/kg) using New Zealand White rabbits (n = 6; 3/sex), 50% of the rabbits died at the only dose level administered. ⁷⁰ The test substance was applied under occlusion to intact or abraded skin for 24 hours then washed off. All rabbits exhibited normal behavior until day 3 when the rabbits became lethargic, had depressed reflexes, and were cold to the touch. They defecated little or none and had clear fluid coming from their noses and mouths. There was reddening of the nictitating membranes and eyelids. There was substantial weight loss. Skin irritation was noted after 24 hours of exposure, including slight to severe erythema, moderate or severe edema, and whitening of the skin. On day 3, there was moderate or severe atonia and moderate or marked coriaceous skin from day 2. Fissuring was observed in 3 rabbits and desquamation in 1. Necropsy revealed brown, liquid fecal matter; lungs adhered to the chest wall and filled with white granular pockets; enlarged gall bladder; and brownish or clear fluid around the nose and mouth. No visible lesions were observed in the rabbits that survived the 14-day observation period.

Tallowtrimonium chloride (100%; 4.0 mL/kg) applied to the intact and abraded skin of New Zealand White rabbits (3/sex) for 24 hours resulted in 100% mortality between days 3 and 8 of observation. ⁷⁰ Clinical signs included drooping head and ears, increased respiration rate, increased heart rate, ataxia, depression, excessive salivation, reduced motor reflexes, reduced or lack of feed consumption and defecation. Moderate to severe skin irritation was observed. There was dilation of dermal blood vessels, gastrointestinal tract, and the brain surface. There was enlarged renal blood vessels and posterior vena cava. The pituitary was dark red to purple.

Three of 6 New Zealand White rabbits (3/sex) died during the 24-hour dermal administration of tallowtrimonium chloride (4.7 mg/kg). ⁷⁰ Two more died during the 14-day observation period. There were no signs of systemic toxicity during exposure. After exposure, the rabbits had depressed reflexes; cold, drooping ears, and intermittent tremors. The 1 surviving rabbit began eating, defecating, and exhibiting normal behavior after 5 days. Slight to moderate erythema, edema, and atonia were observed at the removal of occlusion until death or end of observation period. Necropsy revealed gas-filled, distended large intestines, a thin stomach wall, and red lungs that were adhered to the chest wall.

Polymeric trimonium ingredients

Polyquaternium-10 (4.0 g/kg) was not toxic to rabbits (n = 5). ⁷ The dermal LD₅₀ of a formulation containing polyquaternium-10 (0.5%) was greater than 2 g/kg on the clipped and abraded skin of rabbits.

Straight and branched chain alkyl trimonium ingredients

Intravenous (through tail vein) LD₅₀ values for female SPF-bred NMRI mice and female Sprague-Dawley rats for various alkyltrimethylammonium bromides (C10, 12, 14, 16, and 20) ranged from 2.8 to 20 mg/kg for mice and 5.5 to 44 mg/kg in rats. ⁷⁸ The LD₅₀ values increased proportionally with the length of the alkyl group. Most animals that died did so within 1 minute from apparent respiratory failure. The rest died within 20 minutes and had tail necrosis.

Alkanol trimonium ingredients

No data were available on alkanol trimonium ingredients themselves. However, data were found for choline HCl. The LD₅₀ of choline HCl in Swiss CD-1 holoxenic mice was 53 mg/kg iv ⁷⁶ All animals showed salivation, lacrimation, respiratory depression, and convulsions prior to death. The maximum cholinergic effects were observed within the first hour, and all the animals died during the first 24 hours of observation. The LD₀ was 21.5 mg/kg iv

Alkanol trimonium ingredients

The ip LD₅₀ of choline chloride (50% powder containing 29% colloidal silicic acid and 21% water) was reported to be 225 mg/kg in male and female mice (calculated for pure choline chloride). ⁶⁴ Mice died within 2 minutes at 1600 mg/kg, at 1 hour at 640 and 800 mg/kg, and at 1 day at 500 mg/kg. Clinical signs were abdominal position, increased respiration rate, convulsions, dyspnea, exophthalmus, and cyanosis immediately after administration. Occasional adhesions in the liver were observed at necropsy.

Male albino rats (n = 14) injected with choline at 45 mg/kg had 29% mortality; guinea pigs (n = 45) had 20% mortality. ⁷⁹ When injected with 60 mg/kg, rats (n = 20) had 60% mortality and the guinea pigs (n = 39) had 74% mortality. Animals that lived longer than 30 minutes survived in most cases.

Polymeric trimonium ingredients

Rats (n = 6) exposed to polyquaternium-10 dust (50 g on a tray stirred up by an intermittent fan) was not toxic over 8 hours. ⁷

Straight and branched chain alkyl trimonium ingredients

Sprague-Dawley CD rats (n = 10/sex plus 5/sex in high dose group for recovery study) were administered cetrimonium chloride (24% to 26%; 0, 30, 100, and 300 mg/kg in distilled water) by gavage 5 days/week for a total of 23 or 24 applications. ⁶³ The recovery group was allowed to recover for 27 days. There were no effects on survival, feed consumption, or body weight. The males in the high-dose group had increased water consumption compared to controls. No treatment effects were observed through ophthalmological and hematological examination. Clinical chemistry parameters were unaffected by treatment except a small increase (but within the range of historical controls) in serum alanine aminotransferase (ALT) in both sexes in the high-dose group.

There was a slight increase in absolute and relative adrenal weights and a decrease in absolute and relative spleen weights in males. Necropsy revealed a thickening of the forestomach mucosa, associated with edema and sporadic ulceration in males and females in the high-dose group. Inflammatory edema in the forestomach mucosa, sporadic ulceration, and acanthosis up to papillomatous hyperplasia were observed in both sexes in the high-dose group at microscopic examination. No histopathological or microscopic alterations were observed in the mid- and low-dose groups. All treatment-related effects were reversed following the recovery period. The authors concluded that the oral no observed adverse effect level (NOAEL) was 100 mg/kg.

Alkanol trimonium ingredients

Choline (200 mg/kg) was orally administered to Balb/c mice of both sexes (n = 10) daily for 28 days. ⁴⁷ Saline served as the control. No effects to body weights, organ weights, hematological parameters, splenic cell counts, pathology of the organs, and clinical biochemistry were reported.

Wistar rats were administered l-carnitine and dl-carnitine (1.2 mmol/kg/d) in drinking water for 7 days. ⁸⁰ Neither enantiomerically pure nor racemic carnitine had an effect on glycemia, food ingestion, or water consumption. Both groups had increased free carnitine in the blood.

Straight and branched chain alkyl trimonium ingredients

A 28-day dermal toxicity test using rabbits of 0.5% cetrimonium chloride dose group showed mild, transient dermal irritation. ⁸¹

Cetrimonium chloride (54.5% in aqueous isopropanol) was dermally administered (0 and 0.5%; 0 and 10 mg/kg) to the clipped skin of New Zealand White rabbits (n = 10; 5/sex) for 5 days/week for 4 weeks. ⁶³ Skin was abraded with a clipper head prior to each application. Treated skin was cleaned with water after 6.5 to 7 hours. Two control rabbits died during the study. There were no treatment-related effects to body weight, hematology, organ weight, gross necropsy findings, or histopathology except that treated areas of the skin had mild to marked acanthosis with active mitosis, hyperkeratosis, and necrosis of the epidermis and hair follicles, with some encrustation and exudates. Slight to moderate erythema was observed in all treated rabbits from days 4 to 8; it disappeared in 4 rabbits by day 17. Very slight to slight edema was observed from days 6 to 12 in 4 rabbits; it subsided by day 17. There was intermittent slight edema during week 4 in 2 rabbits and 1 rabbit developed edema on day 20. There was no desquamation or coriaceousness observed. Three rabbits had slight atonia up to week 4. Slight skin fissuring was observed in most of the treated rabbits that typically disappeared by the end of the study. The SCCP concluded that the skin changes were due to local irritation and not evidence of systemic toxicity. The dermal no observed effects level (NOEL) was 10 mg/kg/d.

Polymeric trimonium ingredients

A 21-day dermal toxicity test of a conditioner containing polyquaternium-10 (1%) demonstrated no toxicity to rabbits (n = 10). ⁷

Alkanol trimonium ingredients

Choline (200 mg/kg) was administered ip to Balb/c mice of both sexes (n = 10) every other day for 28 days. ⁴⁷ Saline served as the control. No effects on body weights, organ weights, hematological parameters, splenic cell counts, pathology of the organs, and clinical biochemistry, except for increased creatinine levels, were reported.

Male guinea pigs (n = 10) were administered  choline (50 mg/kg/d) ip for 5 days/week for 8 weeks (40 doses). ⁸² The controls (n = 5) were untreated. They were then killed and necropsied. The treated guinea pigs developed lung lesions consisting of peripheral nodules of small cells, neoplastic bronchiolar epithelium, carcinomatous lesions, and changes in the pleural surface.

Alkanol trimonium ingredients

Choline (200 mg/kg) was administered by inhalation (described as nasally; no further information was provided) under light anesthesia to Balb/c mice of both sexes (n = 10) every other day for 28 days. ⁴⁷ Saline served as the control. No effects on body weights, organ weights, hematological parameters, splenic cell counts, pathology of the organs, and clinical biochemistry were observed.

Alkanol trimonium ingredients

Male albino rats (n = 25) were administered  choline chloride (0, 45, 148.5, 225 mg/kg; 0, 0.1, 0.33 or 0.5 × LD₅₀ of 450 mg/kg) ip for up to 8 months. ⁸³ The rats were killed at 1, 3, or 8 months and necropsied. After the injections, the rats were initially excited and active and then became dull and sluggish. Weight gains were similar between groups except for the mid dose at 3 months, which was greater. There was a dose-dependent decrease in relative lung weight at 1 month and an increase in the high-dose group at 3 months. There was a decrease in relative weight of the liver and thymus at 1 month, which, in the thymus, continued to 8 months. In the high-dose group, relative weights of the peripheral lymph nodes were increased. There was a dose-dependent decrease in thymocytes at 8 months. Peripheral lymph nodes had increased cell counts in all doses at 1 month and decreased until 8 months. Regional lymph nodes had reduced cell counts at 8 months in the mid- and high-dose groups. At 3 months in the mid-dose group, cuboidal bronchiolar epithelium, collections of lymphoid cells around blood vessels and bronchiols were observed. The high-dose group had collections of plasma cells and lymphocytes around bronchiovascular structures.

Straight and branched chain alkyl trimonium ingredients

In the original safety assessment, rats administered cetrimonium bromide at 10, 20, and 45 mg/kg/d in their drinking water for 1 year exhibited decreased body weight gain in the high-dose group. ¹

Alkanol trimonium ingredients

Fischer 344 rats (n not provided) were administered choline chloride (500 mg/kg/d) in feed for 72 weeks followed by 30 weeks of observation. ⁸⁴ Necropsy was performed at 103 weeks. Survival rates, body weights, and relative liver weights were not affected by treatment. The NOAEL was ≥500 mg/kg/d.

Male CD1 mice were fed choline-rich (1.6%; n = 6), choline-deficient (0%; n = 7), or normal choline (0.36%; n = 9) diets for 20 to 24 months. ⁸⁵ There were no differences in body weight throughout the experiment. There were no differences in mortalities, and these were similar to historical survival for this strain of mice. There were no differences in dendritic spine densities.

CD-1 mice were orally administered choline (0 [n = 23] or 1.6% [n = 17]) in feed for 20 to 24 months. ⁸⁶ The mice were killed and the brains examined. There were no differences in body weights over the course of the experiment. There were no differences in the concentrations of choline in the striatum, hippocampus, or the cortex between groups.

Baboons (n = 24; Papio hamadryas) were orally administered normal or increased levels of choline (100 or 500 mg/1000 calories) in their feed for 3 to 4 years. ⁸⁷ Weights were steady or slightly increased throughout the study. Serum transaminases and glutamate dehydrogenase activity were increased in the high-dose group. Bilirubin was increased, albumin was decreased, and total protein was similar in the high-dose group.

Alkanol trimonium ingredients

Male albino rats (n = 10) were administered choline chloride (25 mg in distilled water) ip for 5 d/week. ⁸⁸ Two of the rats were then killed and the lungs necropsied at 90, 180, and 330 days. Controls (n = 5) were handled differently and administered saline intratracheally. Three rats died in the treatment group, none in the control group. At necropsy, the lungs were light pink in color at 90 and 180 days. At 330 days, small white patches appeared on the lobes and the cut surface also revealed clear white mass. At 90 days, sections of lung showed cuboidal type of bronchiolar epithelium along with prominent musculature of the bronchioles and blood vessels. Heavy collections of lymphoid cells around bronchioles were observed together with dilation of lymphatic vessels. A collection of macrophages with pigments as inclusions were observed at the pleural surfaces. Few giant cells were observed in the parenchyrna along with adenomatoid changes. At 180 days, the lungs had hyperreactive ciliated bronchiolar epithelium and mucus adhering on the top of the epithelial lining. The muscles around bronchioles and blood vessels were hypertrophied and found in patches. Heavy collections of plasma cells and lymphocytes were around bronchioles and larger blood vessels. The alveolar macrophages were very prominent and laden with yellowish black pigment. Sporadically, adenomatoid changes of bronchiolar epithelium were found, which were more prominent at 330 days. Examination of the musculature of the bronchioles revealed prominent eosinophilic characteristics and lumen filled with cell debris with slight thickening of pleura.

Ocular Irritation

In the original safety assessment, cetrimonium chloride was classified as a severe ocular irritant as demonstrated by in vitro and in vitro studies. ¹ In the original safety assessment, steartrimonium chloride was found to be severely irritating to the eyes of rabbits and guinea pigs. ¹

In in vivo tests, cetrimonium bromide (25%) and cetrimonium chloride (10%) were severe ocular irritants that caused irreversible damage in rabbits and rats (Table 9). Steartrimonium chloride was rated an irritant in several studies. In in vitro tests, laurtrimonium bromide, cetrimonium chloride, steartrimonium chloride, and behentrimonium chloride were rated mild to severe ocular irritants. Choline chloride was not an irritant. Polyquaternium-28 was rated a minimal irritant. Choline chloride, carnitine, and carnitine HCl may be ocular irritants as demonstrated by in vitro tests. Polyquaternium-33 was reported to be an ocular irritant and polyquaternium-47 was a slight ocular irritant. Polyquaternium-10 was not an ocular irritant to rabbits up to 5% and produced trace irritation in one eye at 10%.

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Table 9.

In Vitro and In Vivo Ocular Irritation Tests.

Species/Test (n)	Test Substance	Results	Reference
In vitro
Bovine corneal opacity and permeability (BCOP) assay	Cetrimonium chloride (10% in minimal essential medium)	Mean score of 66.4 over 12 laboratories (0-25, mild irritant; 25.1-55, moderate irritant; ≥ 55.1, severe irritant)	112
Hemoglobin denaturation assay	Cetrimonium bromide (2%; 0.1 mL)	Moderate irritant	113
BCOP	Cetrimonium bromide (10%)	Extremely irritating	19
Silicon microphysiometer test	Cetrimonium bromide and cetrimonium chloride	Maximum average score (MAS) of 44.00 and 25.50, respectively (0 = nonirritant; 110 = severe irritant)	114
Chorioallantoic membrane vascular assay (CAMVA) and BCOP	Hair-conditioning product containing cetrimonium methosulfate (0.09%)	CMVA: Not predicted to be irritating to eye	115
		BCOP: Mild ocular irritant
Silicon microphysiometer test	Myrtrimonium bromide	MAS=42.70	114
Neutral red uptake (NRU) assay using rabbit epithelial cells (SIRC cell line)	Steartrimonium chloride	IC50 = 1.93 ± 0.534, 2.22 ± 2.22, 1.74 ± 0.933, and 1.96 ± 0.552 µg/mL using culture medium, phosphate-buffered saline (PBS), suspension in culture medium, and all 3 combined as solvents, respectively.	116
Crystal violet staining (CVS) assay	Steartrimonium chloride	IC50 = 1.27 ± 0.283, 1.17, 2.11 ± 1.12, 1.58 ± 0.752 µg/mL using culture medium, PBS, suspension in culture medium, and all 3 combined as solvents, respectively.	116
Irritation assay using Chinese hamster lung (CHL) cells	Steartrimonium chloride (10%)	MAS = 91.3 with a 24-hour average score of 56.3.	117,118
CHL-CVS test	Steartrimonium chloride (10%)	EC50 = 4.20 ± 1.40 μg/mL	117,118
SIRC-CVS assay using SIRC neutral red uptake assay (multilaboratory study)	Steartrimonium chloride	EC50 = 1.74 to 2.11 μg/mL	116
EYETEX system (multilaboratory study)	Steartrimonium chloride	Moderate ocular irritant	119
Hen’s egg test Chorioallantoic membrane (HET-CAM) assay and chorio-allantoic membrane-trypan blue staining (CAM-TB) assay	Steartrimonium chloride (1%, 10%, and 100%)	MAS = 91.3; 24-hour average score 56.3	120
CAMVA & BCOP	Hair-conditioning product containing steartrimonium chloride (0.75%)	CMVA: Not predicted to be irritating to eye	121
		BCOP: Mild ocular irritant
CAMVA & BCOP	Hair-conditioning product containing steartrimonium chloride (0.75%)	CMVA: Not predicted to be irritating to eye	121
		BCOP: Mild ocular irritant
CAMVA & BCOP	Hair-conditioning product containing behentrimonium chloride (5.0%)	CMVA: Not predicted to be irritating to eye	122
		BCOP: Mild ocular irritant
CAMVA & BCOP	Hair-conditioning product containing behentrimonium chloride (5.0%)	CMVA: Not predicted to be irritating to eye	122
		BCOP: Mild ocular irritant
BCOP assay	Choline chloride (5 mg/mL; 0.5%; pH 5.3)	Not considered an irritant.	34
In vivo
Bovine cornea	Laurtrimonium bromide (2 × 10−3 to 10−2 mol/L)	Dose-related development of opacity starting at 10-3 mol/L.	123
Draize test	Cetrimonium bromide (10%)	Rated as extremely irritating	19
Draize test (multi-laboratory study)	Cetrimonium bromide	HC50 = 10.1 ± 12.8 μg/mL	124
Female New Zealand albino rabbits (n = 12).	Cetrimonium chloride (50% active ingredient; 10 µL)	Macroscopic examination and in vivo confocal microscopy revealed increased damage scores compared to controls (p < .05). Histological examination revealed almost complete denudation of the corneal epithelium. Keratocyte injury was detected deep within the stroma, extending to the corneal endothelium in some eyes. There was marked death of keratocytes.	125
Draize eye test (n = 3)	Cetrimonium chloride (10%)	MAS = 69.0. Classified the ocular irritation potential of cetrimonium chloride as severe.	19
Rabbits (n = 3)	Cetrimonium chloride (10%)	MAS score of 69.0. Day 1 49.7. Damage was irreversible.	112
Rabbits (n = 3)	Genamin CTAC (cetrimonium chloride 28%-30%; 0.1 mL)	Swelling of the conjunctivae at 24 hours. At 48 hours, ½ to ¾ corneal surface was affected. Opacity, 1.9; iritis, 1.0; conjunctival redness, 2.3 and conjunctival chemosis, 3.7. Irreversible ocular damage, corneal opacity, and cunjuctival irritation through day 21.	91
New Zealand albino rabbits (n = 3)	Quartamin 60W25 (cetrimonium chloride 24%-26%; 0.1 mL)	Conjuctival irritations as grad 2-3 redness and grad 3-4 swelling up to day 21. Irreversible ocular damage.	91
Rabbit	Cetrimonium chloride 8% of 25% active and 60% of 30% active in an aqueous shampoo matrix	Reversibly irritation at 2.0%	91
Draize test (n not provided)	Steartrimonium chloride	MAS = 91.3 with a 24-hour average score of 56.3	114
New Zealand albino rabbits (n = 3)	Steartrimonium chloride (as Quartamin 86 W; unknown percentage of steartrimonium chloride; 0.1 mL)	No corneal opacity or irititis was observed up to 72 hours. Redness was observed at 1 to 48 hours. All ocular reactions were resolved at 14 days.	91
New Zealand albino rabbits (n = 3; sex not provided)	Steartrimonium chloride and cetrimonium chloride (as Quartamin 60 W; 28% steartrimonium chloride: cetrimonium chloride, 80:20; 2% in distilled water; 0.1 mL)	No corneal opacity or irititis was observed. Conjunctival irritation was observed up to day 7. Swelling was observed up to 48 hours and continued in 2 rabbits until 72 hours. All reactions had resolved by day 14. The authors concluded that the mixture at 0.56% produced transient conjunctival irritation.	102
Male New Zealand albino rabbits (n = 3)	Behentrimonium chloride (10% in 0.5% methylcellulose in purified water; 0.1 mL). Rinsed after 30 seconds.	Grade 2 corneal opacity observed in 1 rabbit at 24 and 48 hours and grade 1 on day 22. 1 rabbit had grade 1 irititis from 1 hours to day 7. Grade 1-3 swelling between 1 and 72 hours; persisted until days 5, 9, and 22. Conclusion: behentrimonium chloride (10%) caused irreversible ocular damage.	63
Male New Zealand albino rabbits (n = 3)	Behentrimonium chloride (80%) in 0.5% methylcellulose in purified water (0.1 mL). Final concentration 6.25%. Rinsed after 30 seconds.	Corneal opacity at 24 hours. Irititis at 24 h, 1 rabbit until 72 hours. Conjuctival irritation (redness) from 1 to 72 hours; subsided after 7, 7, and 15 days. Swelling between 1 and 72 hours; subsided after 5, 6, and 18 days. Conclusion: behentrimonium chloride (6.25%) caused conjunctival irritation.	63
Male New Zealand albino rabbits (n = 3)	Behentrimonium chloride (3%) in 0.5% methylcellulose in purified water (0.1 mL). Rinsed after 30 seconds.	No corneal opacity. Irititis observed at 24 h in all rabbits and 1 at 72 hours. conjunctival irritation (redness) at 1 hours (3/3), 24 hours (2/3), and 48 hours (1/3). Conclusion: behentrimonium chloride (3%) caused transient conjunctival irritation.	63
A male and a female rabbit	Choline chloride (70% aqueous)	Treated eyes were reddening and tearing after 10 minutes. Slight reddening persisted for 3 hours. No eye irritation or effects to the cornea were observed after day 1 and up to 8 days.	20
New Zealand White rabbits (n = 6)	Polyquaternium-28 (20%, 0.1 mL)	Average Draize scores were 13.3, 4.0, and 2.0 at 1 hour and 1 and 2 days; rinsing the eyes had little effect. Was rated as minimally irritating to the rabbit eye.	18
New Zealand White rabbits (n = 3)	Polyquaternium-47 (<30% in aqueous solution)	Conjuctival irritation was observed at 1 hour. All rabbits had moderate chemosis and 1 had moderate discharge. Initially, all the rabbits had conjuctival redness. At 24 hours, 1 rabbit still had conjuctival redness. No signs of corneal or iris irritation were observed. One animal had diarrhea on days 1 and 2 and alopecia on the face on day 3. Authors concluded that polyquaternium-47 was a slight ocular irritant.	77

Straight and branched chain alkyl trimonium ingredients—in vitro

A dermal irritation prediction test of cetrimonium bromide using 3T6 mouse fibroblast cells and NCTC 2544 human keratinocyte cells in neutral red uptake (NRU) assay and 3-(4,5-dimethylthiazol-2-Yl)-2,5-diphenyltetrazolium bromide (MTT) assays was conducted. ⁸⁹ Cetrimonium bromide had IC_50’s of 165.66 ± 19.75 and 102.6 ± 3.96 µg/mL for the 3T6 fibroblasts and 203.23 ± 16.23 and 117.87 ± 13.70 µg/mL for the NCTC 2544 keratinocytes, respectively. The authors concluded that cetrimonium bromide was more irritating than synthetic lysine-derived anionic surfactants.

The relative irritancy potential of cetrimonium bromide (100%) was 518 by the cell suspension agar diffusion test. The relative irritation potential of sodium lauryl sulfate (> 99%) was 995. ⁹⁰ In the original safety assessment, cetrimonium chloride (100%) was classified as a skin irritant in an in vitro study using rat skin. ¹ Behentrimonium chloride mixed with isopropanol (concentration not provided) was reported in an MSDS to be nonirritating in vitro. ¹²

Straight and branched chain alkyl trimonium ingredients—in vivo

Cetrimonium chloride (as Genamin CTAC; 29%; 0.5 mL) was tested on New Zealand albino rabbits (n = 3) under occlusion for 4 hours. ⁶³ There were no mortalities or systemic effects observed. There were slight erythema and edema at 30 minutes. Grades 2 to 3 erythema and 1 to 2 edema were observed up to 72 hours. Dry and brownish patch skin was observed at 48 and 72 hours and at 7 days. There was hardened skin at 7 days, ablation of large scales at 7 and 14 days, and shiny skin at 14 days. Grade 2 erythema was observed at 7 and 14 days. Skin reactions had resolved at day 21. The authors concluded that the test substance was irritating to skin at 29%.

Cetrimonium chloride (as Quartanim 60W25; 25%; 0.5 mL) was tested on New Zealand albino rabbits (n = 3; male). ⁶³ The test substance was placed on shaved skin under semiocclusive dressing for 4 hours. There were no mortalities or systemic effects observed. Grades 2 and 3 erythema were observed up to 14 days. Grades 1 and 2 edema was observed between 60 minutes and 7 days. At day 14, no edema was observed in 2 rabbits and grade 2 edema was observed in the third rabbit. Skin dryness was observed from 24 hours to 14 days. The authors concluded that cetrimonium chloride was irritating to skin at 25%.

In the original safety assessment, steartrimonium chloride (0.75%) was positive in an in vivo skin irritation study using guinea pigs (n = 20). ¹

A single application of steartrimonium chloride (as Genamin STAC; 79.2%; 0.5 g) was tested on New Zealand albino rabbits for 3 minutes (n = 3) and 1 hour (n = 1). ⁶³ The test substance was applied to shaved skin under semiocclusion. There were no mortalities or systemic effects observed. The rabbit exposed for 1 hour had grade 2 erythema up to day 22 and grade 1 edema up to 7 days. At day 22, pink new skin and a scar were noted. No erythema or edema was observed for the rabbits exposed for 3 minutes. The authors concluded that steartrimonium chloride at 79.2% was irritating at 1 hour of exposure but not at 3 minutes.

Steartrimonium chloride and cetrimonium chloride (as Quartamin 86W; 80:20; 28%; 2% and 20%; 0.5 mL) was applied to the shaved skin New Zealand albino rabbits (n = 3) under a semiocclusive patch for 4 hours. ⁶³ There were no mortalities or observed clinical effects. The high-dose group had grade 2 erythema up to 72 hours and followed by crust formation at day 7. Grade 1 edema was observed up to 72 hours. The low dose had grade 1 erythema at 1, 24, and 48 hours in 1 rabbit but no edema was observed. The authors concluded that this mixture of steartrimonium chloride and cetrimonium chloride was irritating to the skin at 20% (4.08% active ingredients) and nonirritating at 2% (0.408% active ingredients).

Behentrimonium chloride (5% in a solution with 0.5% methylcellulose in purified water; 0.5 mL) was applied on the shaved skin of New Zealand albino rabbits (n = 3) under semiocclusion for 3 minutes. ⁶³ There were no mortalities or systemic effects observed. There were no erythema or edema up to 72 hours. The authors concluded that a 5% solution of the test substance was nonirritating after 3 minutes of exposure.

Behentrimonium chloride/cetearyl alcohol mixture (proportion not provided) was reported to be nonirritating to rabbits at 25%. ¹³ No other information was provided.

Behentrimonium chloride (7.7%-8.3% in 5% methylcellulose in purified water; 0.5 mL) was placed on the shaved skin of New Zealand albino rabbits (n = 3) using a gauze pad for 3 minutes. ⁹¹ There were no clinical signs over 5 days. At 1 hour, erythema was observed on all treated rabbits, which resolved by 72 hours. This experiment was repeated. ⁹¹ No erythema or edema was observed at any time period up to 72 hours.

Alkanol trimonium ingredients

According to an MSDS, choline chloride may cause irritation with redness and pain. ¹⁵ According to an MSDS, carnitine and carnitine HCl may cause skin irritation. ¹⁷

Polymeric trimonium ingredients. According to an MSDS, polyquaternium-33 may be a dermal irritant. ⁹² Polyquaternium-47 (<30% in aqueous solution; 0.5 mL) was applied to 2 separate patch sites of New Zealand White rabbits (n = 6) for 24 hours. ⁷⁷ There was no edema during the 48-hour observation period. One rabbit had moderate erythema 30 to 60 minutes after patch removal. All treated rabbits had slight erythema under at least one patch during observation. After 24 hours, 4 rabbits had slight erythema. One rabbit had mucoid diarrhea during most of the observation time. All responses were resolved at 72 hours. The authors concluded that Polyquaterium-47 at <30% was a slight dermal irritant.

Polyquaternium-10 (4 g/kg) caused slight erythema to rabbits. ⁷ In another experiment, there was no irritation at 2% and there was moderate erythema at 5.0% and 10%. A shampoo containing polyquatermiun-10 (0.5%) was a severe skin irritant. A conditioner containing polyquaterium-10 (1%) was not a primary dermal irritant to rabbits on intact and abraded skin.

Straight and branched chain alkyl trimonium ingredients

A guinea pig maximization test was performed on cetrimonium chloride (as Quartamin 60W25; 25% cetrimonium chloride) using Dunkin-Hartley albino guinea pigs (n = 10/sex; control group n = 5/sex). ⁶³ Induction on day 0 was by intradermal injections of 0.125% test substance in saline and/or Freud’s complete adjuvant and on day 7 at 3% (0.75% active). Challenge was a topical application of the test substance at 0.5% (0.125% active ingredient; 0.5 mL) on day 21 and day 28. There were no deaths or clinical signs in the test group. At the first challenge, 3 males of the treatment group and 1 female in the control group had mild erythema. Three males and 1 female in the control group also had mild erythema on the vehicle-treated side. At 48 hours, no skin reactions were observed. Histopathology on all treated skin showed erythema. Reactivity to the vehicle was similar in both groups. SCCP concluded that the results were unclear.

A Buehler test on cetrimonium chloride (as Genamin CTAC; 30% cetrimonium chloride) using Pirbright white guinea pigs (n = 6) was conducted. ⁶³ Dermal induction was at 4% (1.27% active) in distilled water; the challenge was at 1% (0.3% active ingredient). There was slight to well-defined erythema and very slight edema at the treatment sites during induction. There were no skin reactions in the treatment and controls groups at challenge. The authors concluded that the test substance was not a sensitizer under these conditions.

A guinea pig maximization test was performed using Dunkin Hartley albino guinea pigs (n = 10/sex) to test cetrimonium chloride (as Quartanim 60W25; 24%-26% cetrimonium chloride). ⁹¹ Induction was intradermal injections of Qartanim 60W25 (0.125%) and the challenge was topical administration of Quartamin 60W25 (0.5%) on 8 cm² under occlusion for 24 hours. There were no deaths, clinical signs, or changes in body weights. Skin reactions (erythema) were similar between the treatment and control groups.

A Buehler test was performed on steartrimonium chloride (as Genamin STAC; 79.8% steartrimonium chloride) using Pirbright white guinea pigs (n = 20; n = 10 in control group). ⁶³ Induction was at 4% (3.192% active) in ethanol:water (80:20) under an occlusive patch on clipped skin for 6 hours. Induction was repeated on days 8 and 15. The challenge was on day 29 at 1% (0.798%) in isopropanol (instead of ethanol:water) on a naive site. The patch was left on for 6 hours. No clinical signs were observed. During induction, the treated group had slight, well-defined to severe erythema and very slight to well-defined edema at the treatment area. No skin reactions were observed after the challenge. The authors concluded that the test substance was not a sensitizer under these test conditions.

A guinea pig maximization test using Dunkin-Hartley guinea pigs (n = 10; n = 5 in control group) was performed on steartrimonium chloride: cetrimonium chloride (80:20; as Quartamin 86W; 28% active [20.47%]) in distilled water or Freund complete adjuvant (FCA; 50%) and water. ⁶³ Induction was 0.1% v/v (0.0204%) by intradermal injection then a topical patch at 5% (1.20%) on shaved skin for 48 hours. Challenge was at day 21 with a patch at 10% (2.4%) on the right shoulder and 5% (1.2%) on the left for 24 hours. There was well-defined or moderate to severe erythema at the induction sites in the test group at 24 and 48 hours. Slight erythema was noted at the induction sites of the control group at 24 hours and at 48 hours in 1 guinea pig. After topical induction, slight to well-defined erythema was noted at 24 hours in the test group; no reaction was noted in the control group. No skin reactions were observed at the challenge sites. The authors concluded that the test substance was not a sensitizer under these conditions.

Hartley guinea pigs (n = 10/sex in treated group; n = 5/sex in control group) were treated with a 10% solution of behentrimonium chloride (vehicle not stated) on a 8-cm² filter paper patch applied to clipped skin on the left flank for 6 hours, with occlusion on days 1, 8, and 15. ⁶³ During the induction phase, the skin sites were examined for local effects 24 hours after each treatment. The challenge exposure consisted of a 0.5% solution of the test substance loaded onto a Finn chamber and applied to clipped skin on the right flank for 6 hours, with occlusion on day 29. A second challenge was performed on day 43 due to equivocal cutaneous reactions from the first challenge. One male animal from the treated group died on day 14, but this was considered by the investigators to be unrelated to treatment. A few treated animals (number not specified) showed slight to well-defined erythema during the induction phase. After the challenge, grade 1 erythema was observed in 3 of 19 animals at 24 hours and 5 of 19 animals at 48 hours. A grade 1 erythema was observed in 1 of 19 and a grade 2 erythema in 2 of 19 animals at 72 hours. No reactions were observed in control animals, after the challenge. The authors concluded that behentrimonium chloride was a sensitizer at 10%.

A Buehler test for sensitization was performed on behentrimonium chloride (as Genamin KDMP; 77% to 83% diluted to a 20% solution in ethanol:water [80:20]; 16%). ⁶³ Female Pirbright white guinea pigs (n = 20, control n = 10) were treated with a 20% solution of the test substance on a 2 × 2 cm cellulose patch, applied to clipped skin on the left flank for 6 hours, with occlusion on days 1, 8, and 15. During the induction phase, the skin sites were examined for local effects 24 hours after each treatment. The challenge exposure consisted of a 0.8% solution of the test substance in isopropanol on a 2 × 2 cm occluded patch, applied to clipped skin on the right flank for 6 hours, on day 29. Skin reactions were scored 24 and 48 hours after patch removal. Animals were observed daily for signs of systemic toxicity and body weights were recorded on days 1 and 31. Treated animals showed slight to well-defined erythema and very slight edema at the site of treatment during the induction phase. No skin reactions were observed in the treated or control animals after challenge.

In a Buehler test using Dunkin Hartley guinea pigs (n = 10/sex), behentrimonium chloride (as Genamin KDMP; 77%-83%) was used at induction at 10% Genamin KDMP (7.7%-8.3%) and challenge at 0.5% (3.5%-4.25%) in Finn chambers. ⁹¹ No clinical signs were observed and weights were similar between groups. There was some well-defined erythema in some of the treatment groups. There were 3 reactions observed after challenge and no reactions at rechallenge.

Alkanol Trimonium Ingredients

Patients with dyskinesia and cerebellar ataxia were orally treated with choline chloride (150 and 220 mg/kg/d [10 and 16 g/d, respectively] for 2-6 weeks). ⁹⁴ The patients developed fishy body odor, vomiting, salivation, sweating, and gastrointestinal effects.^44,95

Fasting levels of choline in the plasma were reported to be around 10 µmol/L, ranging from 9 to 20 µmol/L. ⁹⁶ A fishy odor from ingested choline has been reported, possibly due to excessive amounts of trimethylamine, a metabolite produced by bacteriological action and formation of methylamines.^44,95

Total body carnitine was reported to be mostly contained in skeletal muscle carnitine (∼20 g of carnitine in a 70-kg man, of which more than 19 g was reported to be in skeletal muscle). ⁹⁷ The bioavailability of orally administered carnitine was reported to be ∼16% to 18% at doses of 1 to 2 g and may be even lower at higher doses.^98,99 Once synthesized or absorbed, carnitine was reported to be eliminated from the body only via the urine as carnitine or acylcarnitines. Renal tubules contain a saturable carnitine transport system that conserves most filtered carnitine but leads to large carnitine losses if the plasma concentration exceeds 60 to 90 μmol/L. Carnitine was reported to be absorbed at ∼25% when consumed orally. ¹⁰⁰

Suspected and known coronary artery disease patients had blood analyzed after an overnight fast. ¹⁰¹ The average free carnitine was 41.9 ± 8.9 µmol/L; short-chain acylcarnitine, 10.5 ± 5.3 µmol/L; total acid-soluble carnitine, 52.4 ± 9.4 µmol/L, long-chain acylcarnitine, 2.8 ± .7 µmol/L, and total carnitine, 55.2 ± 9.9 µmol/L.

Participants (n = 8) were orally administered acetyl-l-carnitine (500 mg) in pill form after overnight fasting. ¹⁰² Blood samples were collected at 0.33, 0.67, 1, 1.5, 2, 3, 4, 6, 8, and 12 hours. The area under the curve (AUC)_0-8 was 9879 ± 3.757 mL/h, AUC_0-12 was 6.611 ± 3.757 mL/h, maximum concentration was 1.188 ± 1.316 hours, mean residence time was 4.5 ± 0.3 hours, elimination half life was 4.2 ± 1.6 hours, and the maximum time to reach maximum concentration was 3.1 ± 0.2 hours.

Alkanol trimonium ingredients

Participants with hyperthyroidism-related symptoms (n = 5) were orally administered l-carnitine (2 or 4 mg/kg/d) for 90 days. ¹⁰³ Mild nausea and gastralgia were reported by 2 participants in the first week. No other adverse effects were reported.

Participants (n = 7) with dementia of the Alzheimer type were orally administered acetyl-l-carnitine (1 g/d) for 24 weeks. ¹⁰⁴ Nausea and vomiting were the only reported adverse effects.

Patients with Alzheimer (n = 7) were orally administered choline chloride (10 g/d, 7.5 g of choline). ¹⁰⁵ The patients developed nausea, diarrhea, and slight hypotension.

Participants, with and without cirrhosis, have been orally administered choline (6 g/d; form not stated) for 4 weeks with no liver toxicity. ¹⁰⁶ Oral ingestion of choline (20 g/d) for 3 to 4 weeks have been associated with depression. ¹⁰⁷ Mild, transient signs of Parkinson disease have been observed in patients with tardive dyskinesia after oral administration of choline (12.7 g/d). ¹⁰⁸ Patients with tardive dyskinesia and Huntington disease who were orally administered choline (20 g/d) for 4 weeks had no adverse effects. ¹⁰⁷

The critical adverse effect from high intake of choline was reported to be hypotension, with corroborative evidence on cholinergic side effects (eg, sweating and diarrhea) and fishy body odor. The Tolerable Upper Intake Level (UL) for adults was reported to be 3.5 g/d.

Straight and branched chain alkyl trimonium ingredients

Laurtrimonium bromide (7.5%) was applied to the volar surface of the arms of 11 white, healthy participants for 20 minutes for 8 consecutive days (excluding weekends, days 5 and 6). ¹⁰⁹ An untreated site and a site treated with water served as controls. The amount of irritation increased with time. The transepidermal water loss (TEWL) measurement did not decrease after the weekend break and did not return to baseline for 20 days after treatment ended. Erythema was still present at 23 days.

In the original safety assessment, slight dermal irritation was observed during the induction phases of multiple human repeated insult patch tests (HRIPT) experiments of cetrimonium chloride (0.25%). ¹

Several studies of dermal irritation of products containing cetrimonium chloride, behentrimonium chloride, and cocotrimonium methosulfate are reported in Table 11. Cetrimonium chloride was not an irritant up to 1% and mixed results were reported above 1%. Behentrimonium chloride was not an irritant at 5.0% and cocotrimonium methosulfate at 0.42%.

OPEN IN VIEWER

Table 11.

Human Dermal Irritation Studies of Cetrimonium Chloride.

Test (Concentration and/or Amount)	N	Results	Reference
Webril (25%; 0.2 mL)	87	Nonirritating	126
Hill Top (25%; 0.2 mL)	87	Nonirritating	126
Finn (25%; 0.4 mL)	87	Nonirritating	126
Van der Bend (25%; 0.03 mL)	87	Nonirritating	126
4-hour Patch test (3.5%, 7.5%, 8.8%)	Not provided	Moderate irritant	127
24-hour Patch test (3.25%)	Not provided	Slightly to moderately irritating	63
1-hour Patch test (2.5%)	Not provided	Minimal skin irritant	63
24-hour Patch test (cosmetic formulation 3.52%; 50% solution)	Not provided	Nonirritating	63
48-hour Patch test (cosmetic formulation 3.2%; 50% solution)	Not provided	Nonirritating	63
24-hour Patch test (1%)	Not provided	Nonirritating	63
24-hour Patch test (formulation 2.0; 50% solution)	Not provided	Nonirritating	63
24-hour Patch test (cosmetic formulation 3.01%; 25% aqueous solution)	Not provided	Minimally irritating	63
24-hour Patch test (cosmetic formulation 4%; 10% aqueous solution)	Not provided	Not irritating	63
24-hour Patch test (styling gel formulation 0.5%; 25%, 50%, 75%, 100% solution)	Not provided	Nonirritating	63

The irritancy potential of a formulation containing behentrimonium chloride (5.0%, vehicle not provided) was tested in participants (n = 51; 5 male and 46 female participants) using a Finn chamber applied to the participants’ backs, with occlusion, for 24 hours. ⁶³ Deionized water was used as the negative control substance. No difference in irritant reactions between treatment and control sites was reported.

Alkanol trimonium ingredients

Bar soap and liquid body soap, with and without choline chloride (0.5%), were used by people (n = 25) with self-perceived sensitivity to choline chloride (0.5%) for 21 days. ²⁰ Compared to controls, there was no difference in cumulative irritancy.

Polymeric trimonium ingredients

Polyquaternium-10 at 5% in water was not a dermal irritant to participants for 21 days of application. ⁷

Polymeric trimonium ingredients

Polyquaternium-28 (2%; 0.2 mL; vehicle not provided) was placed on patches and applied to the volar surfaces of the arms of participants (n = 10). ¹⁸ After 24 hours, 1 arm was exposed to UV-A for 15 minutes. The unirradiated arm served as the control. There were no reactions observed at 24 and 48 hours.

Polymeric trimonium ingredients

Polyquaternium-28 (5%; 0.2 mL; vehicle not provided) was placed on patches and applied to the volar surfaces of the arms of participants (n = 28) 6 times over 3 weeks. ¹⁸ One arm was exposed to UV-A (3.33 j/cm²) and UV-B (90-126 mj) irradiation for 75 to 105seconds (depending on skin type) 24 hours after each application of the test substance. The unirradiated patches and untreated areas served as the controls. Two weeks after the completion of induction phase, a single application of the test substance (2%, 0.2 mL) followed by irradiation was administered to a naive site.

Minimal erythema or erythema and/or slight edema were observed in 26 of the irradiated sites during induction which was similar to untreated irradiated sites in 6 participants. In the challenge phase, minimal erythema was observed in 4 participants on treated irradiated sites and in 1 participant on a treated, nonirradiated site. No reactions were observed on untreated irradiated sites. Overall, slight irritation was observed on treated skin exposed to UV-A and UV-B irradiation, but polyquaternium-28 did not induce contact photoallergy in humans under these conditions.