Antagonism of vecuronium by one of its metabolites in vitro.
The neuromuscular-blocking agent vecuronium bromide undergoes hydrolysis to three pharmacologically active metabolites (3-desacetyl, 17-desacetyl and 3,17-desacetyl vecuronium) which might modify the neuromuscular-blocking action of their parent compound. In order to elucidate the possible role of the interaction between vecuronium and its metabolites in the complications reported after long-term use of vecuronium in intensive care unit (ICU) patients, the relative potency of vecuronium, 3-desacetyl and 3,17-desacetyl vecuronium was determined in the rat hemidiaphragm in vitro and the mode of interaction of the above-mentioned compounds investigated. Dose-response relationships were established for each substance alone and for combinations of vecuronium with its metabolites. The relative potency at the EDmax50 levels (% maximal effect) were in the order of 1:1.2:27 for vecuronium, the 3-desacetyl derivative and the 3,17-desacetyl derivative, respectively. The mode of interaction characterized by isobolographic and algebraic (functional) analysis showed vecuronium and 3-desacetyl vecuronium to interact in an additive fashion while the combined effect of the parent compound and its 3,17-desacetyl derivative was less than additive, indicating antagonism.
Clinics for Anaesthesia and General Intensive Care Medicine, University of Innsbruck, Austria.
K S
KS
Khuenl-Brady
P
P
Mair
J
J
Koller
D000818:Animals; D003964:Diaphragm / Q000187:drug effects; D066298:In Vitro Techniques; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects; D009467:Neuromuscular Depolarizing Agents / Q000494:pharmacology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012132:Respiratory Muscles / Q000187:drug effects; D014673:Vecuronium Bromide / Q000031:analogs & derivatives* / Q000037:antagonists & inhibitors* / Q000378:metabolism / Q000494:pharmacology
D009467:Neuromuscular Depolarizing Agents; C047943:3,17-bis-deacetylvecuronium; C047940:3-deacetylvecuronium; D014673:Vecuronium Bromide