Breastfeeding with Smoking Cessation Products

Nicotine Replacement Products

Nicotine replacement products have been advocated to reduce the risk to breastfed infants of inhaled smoke and toxins in maternal cigarette smoke; however, nicotine might increase the risk of SIDS. Based mostly on animal data, nicotine is thought to be genotoxic and can induce production of reactive forms of oxygen, while also reducing the antioxidant capacity of the lung. Consequently, infants exposed to nicotine might be more prone to asthma and emphysema later in life. Because of these effects, several authors recommend against using any form of nicotine in nursing mothers.^6,7 No well-designed clinical studies have been performed to resolve this issue.

Nicotine replacement therapies are available in short-acting and long-acting dosage forms. The short-acting forms include gum, lozenges, nasal spray, and an oral inhaler. Peak serum concentrations in the users occur in 4–15 minutes after the nasal spray, ∼15 minutes after the inhaler, and 15–30 minutes after the gum. Nicotine is primarily absorbed through the mucous membranes in the mouth and respiratory tract (for the inhalation), but very little is absorbed through the lung or gastrointestinal tract. Maternal plasma nicotine concentrations after using the nicotine spray are about one-third those of smokers, so milk concentrations are probably proportionately less. Maternal nicotine plasma concentrations after using nicotine gum are variable depending on the vigor of chewing and number of pieces chewed daily, but can be similar to those attained after smoking cigarettes. One source recommends the short-acting agents over the patches, but no studies have compared the various forms of nicotine replacement in nursing mothers.

Nicotine-containing patches are one of the most common nicotine replacement products. Nicotine from patches reaches peak serum concentrations in 6–8 hours, but maintains more persistent serum levels. With a 21 mg transdermal patch, nicotine passes into breast milk in amounts equivalent to smoking 17 cigarettes daily. Lower patch strengths of 14 and 7 mg provide proportionately lower amounts of nicotine to the breastfed infant. Nine breastfed infants with an average age of 4.8 months whose mothers were using nicotine patches for smoking cessation had plasma concentrations of the nicotine metabolite cotinine measured during maternal use of a 21 mg nicotine patch. Infant plasma cotinine averaged 22 mcg/L, which was 13.4% of the simultaneous maternal cotinine plasma concentrations. In this study of nursing mothers who were using nicotine patches, average milk production was 17% lower than average literature values as judged by infant milk intake, which was similar to reductions in smoking mothers. However, the study did not directly compare the milk production of smokers with that of nonsmokers. In a study of the infants of five of the mothers who were using 21 mg nicotine patches for smoking cessation, the infants' average Denver developmental age was equivalent to their chronological age at the time of patch use.

In summary, although nicotine replacement products may be the first choice for smoking cessation in the general smoking population, their status in nursing mothers is not clear. Short-acting agents such as gums and sprays have the advantage of possibly timing around doses by nursing just before use. Only the patches have been studied in nursing mothers, showing that milk nicotine intake by breastfed infants is similar to that from smoking mothers, but without the other toxins associated with tobacco or possibility of second-hand smoke exposure. Some investigators shun all nicotine products during breastfeeding over concern on impaired lung development and increased risk of SIDS. No definitive infant outcome data are available.

Electronic Nicotine Delivery Systems

Electronic nicotine delivery systems (ENDS), such as e-cigarettes and other vaping products, have been touted as a method to quit smoking, although they are not FDA approved for this use. Recent meta-analyses indicate that they may be effective in helping smokers to quit.^8,9 Some mothers who smoked before pregnancy use e-cigarettes postpartum to help them avoid returning to smoking. ¹⁰

The vapors from ENDS contain potentially toxic and carcinogenic substances similar to those in tobacco smoke, but at lower levels. Likewise, the urine of ENDS users also contain lower levels of the toxins and carcinogens found in tobacco smokers' urine. ¹¹ It is possible that some of these substances enter breast milk, but no studies have been performed that measure nicotine or other toxic substances in milk or effects on breastfed infants after maternal ENDS use. A recent analysis of Pregnancy Risk Assessment and Monitoring System data found that women who used ENDS during the last 3 months of pregnancy (and probably continued during breastfeeding) were less likely to be nursing at 3 months postpartum than mothers who did not use them (40.8% versus 68.5%). ¹²

Bupropion

The antidepressant bupropion has some nicotinic receptor-blocking activity and may also act by inhibiting dopamine reuptake. Only the sustained-release formulation of bupropion is approved as a smoking cessation aid in a dose of 150 mg twice daily. It is started 7–14 days before the target quitting date so that serum concentrations will be stabilized. Bupropion is metabolized to three metabolites (hydroxybupropion, erythrohydroxybupropion, and threohydroxybupropion) with the antidepressant activity of each ∼50% that of bupropion.

A total of 14 mothers who were taking sustained-release bupropion in daily dosage of 150 or 300 mg have been studied. In one study, the authors estimated that an exclusively breastfed infant would receive an average of 2% of the maternal weight-adjusted dosage of bupropion plus metabolites. In the other study, milk bupropion dosage averaged 5.1% (range 1.4–10.6%) of the maternal weight-adjusted dosage. Two infants whose mothers were taking immediate-release bupropion had undetectable bupropion and metabolites in their urine. Of three breastfed infants ranging in age from 14 to 56 days whose mothers were taking bupropion 150 or 300 mg of sustained-release bupropion, only one of the infants' urine samples had detectable amounts of bupropion, but metabolites were not measured.

Several infants have been reported to have no adverse effects from bupropion in breast milk, even at the maximum maternal dose of 300 mg daily. However, three infants whose mothers were taking long-acting forms of bupropion in a dosage of 150 mg daily had seizures or seizure-like activity. Strangely, these infants were 6–6.5 months of age and only partially breastfed, so the link between bupropion and the seizures is questionable.

Varenicline

Varenicline is a nicotinic receptor partial agonist that selectively binds to α4β2 neuronal nicotinic acetylcholine receptors, which mediate release of dopamine in the brain. Varenicline has greater affinity for the α4β2 receptor than nicotine, thereby reducing the reward of smoking. Varenicline should be started 7 days before the target quit date to allow serum concentrations to reach steady state. Varenicline is sometimes used in combination with nicotine replacement.

No information is available on the use of varenicline during breastfeeding or its effect on breastfeeding or milk production. One researcher points out that based on animal data on nicotine, varenicline might interfere with normal infant lung development similar to nicotine and recommends against its use in nursing mothers. ⁶ Because no information is available on the use of varenicline during breastfeeding, an alternative drug is preferred, especially while nursing a newborn or preterm infant. According to the manufacturer, if a mother chooses to breastfeed while taking varenicline, she should monitor her infant for seizures and excessive vomiting.

Nortriptyline

Nortriptyline is a second-line therapy for smoking cessation. Because of the low levels of nortriptyline in breast milk, amounts ingested by the infant are small. Nortriptyline is usually not detected in infant serum, although its less-active metabolites are often detectable in low levels. Immediate side effects have not been reported and a limited amount of follow-up has found no adverse effects on infant growth and development.

Clonidine

Although not FDA approved for this use, clonidine has been used as a second-line therapy for smoking cessation. After maternal clonidine use, high serum clonidine levels have been found in their breastfed infants. Clonidine also has complex dose-related effects on both oxytocin and prolactin secretion. The net effect of the drug on lactation has not been well studied. Clonidine is best avoided in nursing mothers.

Summary

No smoking cessation therapy appears to be ideal for nursing mothers. Either they have potential toxicity for the breastfed infant or they have not been adequately studied for efficacy. Nevertheless, some of the smoking-cessation products might be preferable to continued smoking during breastfeeding.