Clinical Pharmacology of Propofol: An Intravenous Anesthetic Agent

Abstract

Propofol is a 2,6-diisopropylphenol with sedative-hypnotic properties. Because of its slight solubility in water, the drug is formulated as an emulsion for clinical use. It is highly lipophilic and distributes extensively in the body. The blood concentration-time profile of propofol after an iv bolus injection follows a three-compartment model with half-lives of 2–4 min, 30–45 min, and 3–63 h, respectively. Propofol is extensively metabolized by the liver prior to its elimination by the kidney. Following an iv dose of 2–2.5 mg/kg, loss of consciousness occurs in less than one minute and lasts for approximately five minutes. Hypnosis can be maintained by propofol blood concentrations of 1.5–6 μg/mL in the presence of N2O/O2 (60:40 ratio) or other anesthetic agents. During induction, propofol decreases the systolic and diastolic blood pressure by approximately 20–30 percent with minimal change in heart rate; apnea is also common. The cardiovascular and respiratory effects of propofol, however, should not cause major concern in otherwise healthy patients. By virtue of its pharmacokinetic profile, the drug lends itself to continuous infusion for maintenance of anesthesia. When used as the main anesthetic agent, it produces satisfactory anesthesia with rapid recovery and without major adverse effects in healthy individuals. In continuous infusion propofol can be used as an alternative to inhalation anesthetics.