Chapter: Modern Pharmacology with Clinical Applications: General Anesthesia: Intravenous and Inhalational Agents

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Propofol

Propofol (Diprivan) is rapidly acting, has a short recov-ery time, and possesses antiemetic properties.

Propofol

Propofol (Diprivan) is rapidly acting, has a short recov-ery time, and possesses antiemetic properties. A rapid onset of anesthesia (50 seconds) is achieved, and if no other drug is administered, recovery will take place in 4 to 8 minutes. The recovery is attributed to redistribution of the drug and rapid metabolism to glucuronide and sulfate conjugates by the liver and extrahepatic tissues, such as intestine and kidney.

Rapid recovery and its antiemetic properties make propofol anesthesia very popular as an induction agent for outpatient anesthesia. Propofol can also be used to supplement inhalational anesthesia in longer proce-dures. Both continuous infusion of propofol for con-scious sedation and with opioids for the maintenance of anesthesia for cardiac surgery are acceptable techniques.

Pharmacological Actions

Propofol is primarily a hypnotic drug with substantial cardiorespiratory depressant actions and with no ability to produce neuromuscular blockade. While propofol lacks analgesic properties, its use permits lower doses of opioids. Likewise, less propofol is required for adequate hypnosis when it is administered with opioids. Thus, it is said that propofol and opioids interact synergistically.

Adverse Effects

The dose of propofol should be reduced in older pa-tients; however, it does have a relatively linear dose– response characteristic, and patients generally can besafely titrated. The pain on injection, especially when small veins are used, can be considerably reduced if li-docaine 20 mg is administered first.

Anesthesia induction with propofol causes a signifi-cant reduction in blood pressure that is proportional to the severity of cardiovascular disease or the volume sta-tus of the patient, or both. However, even in healthy pa-tients a significant reduction in systolic and mean arte-rial blood pressure occurs. The reduction in pressure appears to be associated with vasodilation and myo-cardial depression. Although propofol decreases sys-temic vascular resistance, reflex tachycardia is not ob-served. This is in contrast to the actions of thiopental. The heart rate stabilization produced by propofol rela-tive to other agents is likely the result of either resetting or inhibiting the baroreflex, thus reducing the tachy-cardic response to hypotension.

Since propofol does not depress the hemodynamic response to laryngoscopy and intubation, its use may permit wide swings in blood pressure at the time of in-duction of anesthesia. Propofol should be used with ut-most caution in patients with cardiac disease.

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