Pancuronium

Pancuronium bromide produces pharmacologic effects similar to those of other non-depolarising neuromuscular blocking agents. The drug may produce an increase in heart rate which appears to result from a direct blocking effect on the acetylcholine receptors of the heart. The increase in heart rate appears to be dose related and is minimal with usual doses. Pancuronium bromide causes little or no histamine release and no ganglionic blockade and therefore does not cause hypotension or bronchospasm. Despite its steroidal structure, the drug exhibits no hormonal activity.

Absorption

Following I/V administration of pancuronium bromide 60 micrograms/kg, muscle relaxation reaches a level suitable for endotracheal intubation within 2-3 minutes, slightly more rapidly than with tubocurarine. The onset and duration of paralysis are dose related. After a dose of 60 micrograms/kg, the effects of the drug begin to subside in about 35-45 minutes. Supplemental doses may increase the magnitude and duration of the neuromuscular blockade. The duration of action depends upon the clinical condition of the patient and the dose administered, but in normal subjects receiving perioperative muscle relaxant doses the duration of action is usually 45-60 minutes.

Distribution

Protein binding of pancuronium bromide does not appear to be substantial. The activity of the drug is not greatly affected by plasma carbon dioxide concentrations or pH. Redistribution is responsible for the termination of activity following single doses. Pancuronium bromide crosses the placenta in small amounts.

Elimination

Plasma concentrations appear to decline in a triphasic manner. In adults with normal renal and hepatic function, the half-life in the terminal phase is about 2 hours. The elimination half-life may be prolonged in patients with impaired renal and/or hepatic function. The drug is eliminated mainly unchanged by the kidneys, although small amounts may be metabolised and some of the drug may be eliminated in the bile.

None.