Pharmacology of neuromuscular blockade: interactions and implications for concurrent drug therapies

Neuromuscular blocking agents (NMBAs) have historically been utilized in the operating room as an adjunct to general anesthesia to induce skeletal muscle relaxation. Within the past decade, their use has been extended to the intensive care setting to facilitate tracheal intubation, provide paralysis in patients unable to tolerate mechanical ventilation, or aid in the management of ventilatory failure. Numerous factors must be considered when selecting a potential NMBA for use: speed of onset, route of elimination, potential for adverse effects (cardiovascular or histamine release), potential for "cumulative" effect, intermittent or continuous infusion administration capability, and potential for drug-drug interactions. This article is concerned with the pharmacology, pharmacokinetics, and physiology of those NMBAs that are commonly prescribed and their therapeutic usefulness in the treatment of the critically ill.