Comparison in young and elderly patients of pharmacodynamics and disposition of labetalol in systemic hypertension.
Pharmacodynamics and pharmacokinetics of labetalol, a combined alpha- and beta-adrenoceptor antagonist drug, were studied in elderly and young hypertensive patients. After receiving intravenous labetalol, elderly patients had a greater maximal mean decrease in systolic blood pressure (BP) (39 +/- 8 vs 25 +/- 13 mm Hg, p less than 0.02); however, maximal decrease in diastolic BP was similar in elderly (18 +/- 10 mm Hg) and young (17 +/- 6 mm Hg) patients. After receiving oral labetalol, elderly patients had a greater maximal decrease in standing systolic BP (41 +/- 16 vs 16 +/- 14 mm Hg, p less than 0.001) and similar decreases in standing diastolic BP (21 +/- 7 vs 17 +/- 9 mm Hg). Sitting maximal BP decreases after oral labetalol treatment were similar in elderly and young patients (12 +/- 16 vs 17 +/- 7 mm Hg systolic and 24 +/- 6 vs 12 +/- 7 diastolic). The decrease in heart rate was greater in young patients after intravenous labetalol administration. To evaluate labetalol pharmacodynamics, a linear model was used. Slope of labetalol concentration vs systolic BP for elderly vs young patients was 0.928 +/- 1.05 vs 0.326 +/- 0.490 ng/ml X mm Hg-1 (difference not significant). The slope of labetalol concentration vs heart rate for elderly vs young patients was 0.176 +/- 0.063 vs 0.406 +/- 0.303 ng/ml X beats/min-1 (p less than 0.05), with 2 elderly patients showing no decrease in heart rate.(ABSTRACT TRUNCATED AT 250 WORDS)
Abernethy
D R
DR
Section on Hypertension/Clinical Pharmacology, Baylor College of Medicine, Houston, Texas.
Schwartz
J B
JB
Plachetka
J R
JR
Todd
E L
EL
Egan
J M
JM
D000328:Adult; D000368:Aged; D001794:Blood Pressure / Q000187:drug effects; D005260:Female; D006801:Humans; D006973:Hypertension / Q000188:drug therapy* / Q000378:metabolism / Q000503:physiopathology; D007741:Labetalol / Q000097:blood / Q000493:pharmacokinetics / Q000627:therapeutic use*; D008297:Male; D008875:Middle Aged
D007741:Labetalol