The pharmacokinetics of the enantiomers of atenolol.
A number of studies have demonstrated that lipophilic beta-adrenoceptor blocking agents, eliminated almost exclusively by hepatic metabolism, are stereoselectively metabolized in human beings. Previous studies in our laboratory have demonstrated that pindolol, a beta-adrenoceptor blocking agent of intermediate lipophilicity that is eliminated by both hepatic metabolism and renal excretion, is eliminated stereoselectively in the kidney. In the present study we examined the pharmacokinetics of the enantiomers of atenolol, a hydrophilic cardioselective beta-adrenoceptor blocking agent that is eliminated almost exclusively by the kidney. A single 100 mg oral dose of racemic atenolol was administered to six healthy adult men. Concentrations of d- and l-atenolol in plasma and urine were measured by a stereospecific HPLC analytic procedure. In each subject the peak concentration of d-atenolol was greater than the peak concentration of l-atenolol (mean +/- SD of 420 +/- 81 ng/ml vs 366 +/- 61 ng/ml; p less than 0.05). The peak concentration of both enantiomers was reached at the same time in each subject (between 2 and 3 hours). The renal clearances of d- and l-atenolol were not significantly different (109.7 +/- 33.5 ml/min vs 112.5 +/- 36.7 ml/min), probably because the major route of renal elimination is glomerular filtration. The half-lives of d- and l-atenolol were not significantly different (mean +/- SD of 4.6 +/- 1.1 hours vs 5.2 +/- 0.9 hours). However, both the AUC and the amount excreted unchanged in the urine in 24 hours Ae [0-24]) were significantly greater for d-atenolol than for l-atenolol (p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)
Boyd
R A
RA
Department of Pharmacy, School of Pharmacy, University of California, San Francisco 94143.
Chin
S K
SK
Don-Pedro
O
O
Williams
R L
RL
Giacomini
K M
KM
D000328:Adult; D001262:Atenolol / Q000097:blood / Q000493:pharmacokinetics* / Q000494:pharmacology / Q000652:urine; D001682:Biological Availability; D002851:Chromatography, High Pressure Liquid; D005919:Glomerular Filtration Rate; D006207:Half-Life; D006801:Humans; D008297:Male; D008657:Metabolic Clearance Rate; D013223:Statistics as Topic; D013237:Stereoisomerism
D001262:Atenolol