The Anesthesia Record

Unlike most nondepolarizing neuromuscular relaxing agents which are metabolized via the liver, atracurium (Tracium) is cleared from systemic circulation via Hofmann Elimination.  (And secondarily by ester hydrolysis, but that's neither here nor there...)  Thus, at standard temperature and pH, the drug is spontaneously metabolized.  Atracurium clearance is therefore not dependent on organ function and may be administered to patients with liver or kidney impairment, for example.

But what about patients who don't meet the requirements of "standard temperature and pH"?  Well, Hofmann Elimination still occurs, just at varied rates.  It is decreased by acidosis and diminished body temperature.  Conversely, states of alkalosis and heightened temperature increase the metabolism of Hofmann Eliminated drugs.

The way I remember this is easy: As pH and temperature decrease, Hofmann Elimination also decreases.  As pH and temperature increase, Hofmann Elimination increases.  Thus, a febrile patient, for instance, would require a higher dose (or more frequent dosing) of atracurium to remain pharmacologically paralyzed than would a normothermic patient.

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