Journal of Pharmacy Practice

Intravenous (IV) anesthetics are used in the operating room setting for the induction and maintenance of general anesthesia. These agents are used in combination with many other therapeutic agents including inhalational anesthetics, anticholinergics, neuromuscular blockers, local anesthetics, and antihistamines. Currently available intravenous anesthetics include barbiturates (eg, thiopental and methohexital), benzodiazepines (eg, diazepam and midazolam), etomidate, ketamine, propofol, and opioids (eg, morphine, meperidine, fentanyl, alfentanil, and sufentanil). The barbiturates are the most frequently used agents for induction today. The benzodiazepines are used primarily for preoperative sedation intraoperatively; however, they may also be used for induction in certain clinical situations. Etomidate offers the advantage of minimal cardiovascular side effects, while ketamine is distinguished by stimulant cardiovascular effects. Propofol has a short recovery time and a low incidence of nausea and vomiting when compared with that of barbiturates and opioids. The opioids are used most often for the production of analgesia, although they may also be used as primary anesthetic agents in select patient populations. In this article, the pharmacokinetics of these agents will be reviewed as well as factors affecting their pharmacokinetic profile. These factors include age, hemodynamic changes, renal or hepatic dysfunction, and interaction with concomitant medications.

Neuromuscular blocking (NMB) agents are frequently used in the operating room (OR) as well as the intensive care units. The number of NMB agents available for use in these areas continues to increase. The clinician currently has 10 agents from which to choose, with another (rocuronium) soon to be available. NMB agents are classified as either depolarizing or nondepolarizing. Succinylcholine is the only depolarizing agent in clinical use today. It has the fastest onset of action of all NMB agents, but also the most adverse effects. The nondepolarizing agents as a group can be further differentiated by several characteristics: duration of action, cardiovascular effects, routes of metabolism/excretion, and cost. This allows an agent to be chosen based on patient parameters. Acetylcholinesterase inhibitors can be used to reverse residual neuromuscular blockade. The introduction of agents such as mivacurium, with a short duration of action, may reduce the need for acetylcholinesterase inhibitors; instead, neuromuscular function can be allowed to recover spontaneously. Finally, several factors must be considered when determining whether to add an agent to formulary: surgical case mix, patient acuity, agents currently on formulary, and cost of the new agent compared with those already on formulary.

Pharmacists have traditionally had little involvement with inhalational anesthetic agents. As the popularity of operating room pharmaceutical care increases, the need for the pharmacist's understanding of the uses and actions of anesthetic agents becomes necessary. This review provides an introduction to inhalational anesthesia, delivery systems, and the agents commonly used in anesthetic practice. Inhalational agents have long been used to provide general anesthesia through combined pharmacological actions. Nitrous oxide and oxygen are delivered as sole gasses or as carrier vehicles for the more potent inhalational anesthetics: halothane, enflurane, isoflurane, sevoflurane, and desflurane. The minimum alveolar concentration (MAC) of anesthetics is a measurement of concentrations that will prevent reflex movement in 50% of patients. A low blood/gas solubility coefficient for inhalational agents is desirable and is equated with low metabolism, rapid onset, and short duration of action. The inhalational agents are depressants to the nervous and respiratory systems and have variable effects on the cardiovascular system. Potent volatile agent induced renal toxicity may be a result of fluorine produced as a byproduct of hepatic metabolism. Newer agents favorably show lower solubility characteristics and increased physical and metabolic stability.

Postoperative pain can be effectively managed with epidurally administered opioids or local anesthetics. This article briefly reviews spinal cord anatomy. Pharmacokinetic and pharmacodynamic properties of epidurally administered opioids and local anesthetics are outlined. The pharmacist's participation in a pharmaceutical care plan for the acute postoperative pain patient is also discussed.