Describe Atracurium in detail.

Pharmacology

Atracurium is an intermediate-acting non-depolarising (benzylisoquinolinium) relaxant. Its distinctive feature is its elimination by Hofmann degradation — a spontaneous, non-enzymatic breakdown at normal body temperature and pH — together with ester hydrolysis, both independent of the liver and kidney.

Significance & Adverse Effects

Because its elimination does not depend on organ function, atracurium is the relaxant of choice in renal or hepatic failure, where other agents accumulate. Its main drawback is histamine release (hypotension, flushing, bronchospasm), which is dose-related. Its breakdown product laudanosine can (in very high doses) cause CNS excitation. Cisatracurium, an isomer, shares Hofmann elimination but causes little histamine release.

Temperature & PH Dependence

A practical consequence of Hofmann degradation is that it depends on normal body temperature and pH: hypothermia and acidosis slow the breakdown and prolong the block, whereas the reverse speeds it, so the duration of atracurium can vary a little with the patient’s physiological state. This organ-independence nonetheless makes it and cisatracurium the logical choices whenever hepatic or renal function is severely impaired, and cisatracurium is often preferred in the critically ill because it combines this reliable elimination with minimal histamine release and cardiovascular stability.

Note

So its duration can lengthen a little in the cold, acidotic patient, but it never depends on the liver or kidney.

Safe in renal and hepatic failure — clearance is organ-independent.

• Atracurium: intermediate non-depolarising (benzylisoquinolinium); Hofmann degradation + ester hydrolysis.
• Elimination organ-independent → relaxant of choice in renal/hepatic failure.
• Adverse: histamine release (hypotension, bronchospasm); laudanosine (CNS, high doses).
• Cisatracurium: same Hofmann elimination, minimal histamine.