Background: In recent years it has become clear that gender differences exist both in the pharmacokinetics and the pharmacodynamics of drugs related to the practice of anesthesia. Differences in pharmacokinetics are more straightforward to study than differences in clinical effects. However, isolated pharmacokinetic data are of less value if they are not accompanied by measurements of clinical effects. Males are more sensitive than females to propofol. It may therefore be necessary to decrease the propofol dose by 30-40% in males. Females have 20-30% greater sensitivity to the muscle relaxant effects.
Methods: Anaesthesia is induced with propofol 2 mg/kg (t0) followed by cisatracurium 0.1 mg/kg 1 min from propofol administration (t2). Patients will be monitored using the conventionally available bispectral index monitoring for propofol concentrations and Relaxometer mechanomyograph neuromuscular monitoring for cisatracurium. Serial arterial blood samples (5 ml) were withdrawn in EDTA-tubes before cisatracurium administration, 1, 3, 5, 7, 10, 13, 16, 19, 22, 25, 30, 60 and 90 min following administration. Blood samples were assayed in duplicate using high performance liquid chromatograph. Pharmacokinetic analysis was performed by fitting the cisatracurium blood concentration time profile of individual patients, to non-compartmental as well as multi-compartmental pharmacokinetic models.
