DRUG INTERACTIONS AND OTHER FACTORS AFFECTING RESPONSE TO NEUROMUSCULAR BLOCKERS

A drug-drug interaction is an in vivo phenomenon that occurs when the administration of one drug alters the effects or kinetics of another drug. In vitro physical or chemical incompatibilities are not considered drug interactions.^[420]

Mechanisms of Drug Interactions

Pharmacokinetic interactions are interactions in which one drug alters the rate or amount of absorption, distribution, metabolism, or excretion of another drug (or any combination of these processes).

Pharmacodynamic interactions occur when the dose-response relationship of a drug is altered by the coadministration of a second drug. These interactions are generally described as being synergistic, antagonistic, or additive.

Many drugs have been shown to interact with neuromuscular blockers or their antagonists, or both, and it is beyond the scope of this chapter to review them all. The reader is referred to reviews on drug interactions for more detailed information.^{[420] [421] [422] [423]} Some of the more important drug interactions are discussed in the following sections.