Gender differences in the pharmacokinetics of propofol in elderly patientsduring and after continuous infusion

Differences in the pharmacokinetics of propofol between male and female pat ients during and after continuous infusion have not been described in detai l in patients aged 65 yr and older. To increase our insight, into the pharm acokinetics of propofol in this patient population and to obtain pharmacoki netic parameters applicable in target controlled infusion (TCl), the pharma cokinetics of propofol during and after continuous infusion were studied in 31 ASA class 1 and 2 patients, aged 65-91 yr, scheduled for general surger y. Patients received propofol 1.5 mg kg(-1) i.v. in 1 min followed by 7 mg kg(-1) h(-1) until skin closure in the presence of a variable rate infusion of alfentanil during oxygen-air ventilation. On the basis of arterial bloo d samples that were taken up to 24 h post-infusion. the pharmacokinetics of propofol were evaluated in a two-stage manner. Multiple linear regression analysis was used to explore the effect of age, weight, gender and lean bod y mass as covariates. Gender significantly affected the pharmacokinetics of propofol. V-3 Cl-1 and Cl-2 were significantly different between male and female patients, weight only affected Cl-1. The pharmacokinetic parameters were: V-1=4.88 litre, V-2=24.50 litre, V-3 (litre)=115+147xgender (gender: male=1, female=2), Cl-1 (litre min(-1))=-0.29+0.022x weight+0.22xgender, Cl -2 (litre min(-1)=2.8-0.65xgender (male= 1, female=2), and Cl-3=0.788 litre min(-1).