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Cumulative dose‐response with infusion: a technique to determine neuromuscular blocking potency of atracurium and vecuronium
Author(s) -
Smith Charles E,
Donati Francois,
Bevan David R
Publication year - 1988
Publication title -
clinical pharmacology and therapeutics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.941
H-Index - 188
eISSN - 1532-6535
pISSN - 0009-9236
DOI - 10.1038/clpt.1988.113
Subject(s) - adductor pollicis muscle , neuromuscular blockade , potency , cumulative dose , pharmacokinetics , neuromuscular monitoring , pharmacodynamics , medicine , neuromuscular blocking agents , anesthesia , atracurium besilate , vecuronium bromide , muscle relaxation , pharmacology , chemistry , surgery , ulnar nerve , biochemistry , elbow , in vitro
The ability of cumulative dose‐response techniques to obtain accurate data is most likely limited by redistribution and elimination of the drug during the study period. Therefore the usefulness of these techniques would be improved by replacing the amount of drug lost. This hypothesis was assessed for the intermediate‐duration neuromuscular blockers vecuronium and atracurium, and calculations were made based on a pharmacokinetic model with an effect compartment. Sixty patients received either single doses (SD) (n = 36), cumulative doses (CD) (n = 12), or CD of vecuronium or atracurium with an infusion (CDI) to replace eliminated or redistributed drug (n = 12). The force of contraction of the adductor pollicis muscle in response to train‐of‐four stimulation was measured and recorded. Linear regressions were obtained between the logit transformation of neuromuscular blockade at the adductor pollicis and log dose. The potencies obtained with all three methods were within 20% of each other. For vecuronium the ED 90 was (mean ± SE) 0.034 ± 0.002 (SD), 0.037 ± 0.003 (CD), and 0.036 ± 0.003 mg/kg (CDI). For atracurium the ED 90 was 0.175 ± 0.009 (SD), 0.206 ± 0.019 (CD), and 0.179 ± 0.015 mg/kg (CDI). Calculated values corresponded well with measured values. The calculations predicted that the agreement between single‐ and cumulative‐dose techniques would be improved if (1) the dose increment was increased, (2) the elimination half‐life was increased above 20 minutes, or (3) an infusion was added. It is concluded that for muscle relaxants of intermediate durations of action, the use of an infusion to compensate for drug lost by redistribution or elimination improves accuracy of the cumulative‐dose technique. Clinical Pharmacology and Therapeutics (1988) 44, 56–64; doi: 10.1038/clpt.1988.113