Pharmacokinetics of intravenous bisoprolol in obese and non-obese volunteers.

The pharmacokinetics of a single i.v. dose of dl-bisoprolol 0.16 mg.kg-1 ideal body weight has been studied in 8 obese women (mean weight 91 kg; 161% of ideal body weight) and 8 non-obese women (51 kg; 94% of ideal body weight). Compared to the controls, the obese subjects showed an increase in the total apparent volume of distribution (Vz) (182 vs 1351) and a decrease in Vz per kg body weight (2 vs 2.71.kg-1). There was a negative correlation between Vz l.kg-1 and the percentage of ideal body weight (r = -0.672). Total body clearance was increased, but t1/2 and renal clearance was unchanged. It is concluded that tissue diffusion of bisoprolol in obese subjects is limited, despite its lipophilicity, possibly because of alteration in the blood flow to adipose tissue produced by bisoprolol.