Vecuronium pharmacokinetics in patients with major burns

BackgroundBurn patients develop resistance to non-depolarizing neuromuscular blocking agents (NDNMBAs) and require a significantly large dose to produce a desired clinical response. Pathophysiological changes related to burn injury may alter pharmacokinetics (PK) and pharmacodynamics of NDNMBAs. The purpose of this study was to compare vecuronium PK in burns vs non-burns.MethodsTwenty adults, aged 23-58 yr, with 27-81% total body surface area (TBSA) burn, were studied at 4-57 post-burn days and compared with age- and sex-matched, non-burn controls. Vecuronium 0.12 mg kg^-1 was given i.v. as a single bolus within 10 s. Blood samples (n=20) were collected over 12 h at predetermined time points. NONMEM was used to describe plasma drug concentration-time profiles for burns and non-burns.ResultsA three-compartment model best described vecuronium concentration-time profiles. Burn patients showed enhanced distributional clearance at the terminal phase (0.12 vs 0.095 litre min^-1, P<0.0001), which yielded shorter elimination half-life for vecuronium (5.5 vs 6.6 h, P<0.001). BURN was the single most significant covariate that explained the altered vecuronium disposition in burns.ConclusionsThe altered drug distribution between tissues may partially explain the known resistance to vecuronium in patients with major burns.