title: Beta-blockers: once or three times a day?
abstract: In a double-blind, crossover trial 16 hypertensive patients were treated, in random order, with placebo, metoprolol 300 mg in a single daily dose, or metoprolol 300 mg/day in three doses. Both therapeutic regimens produced detectable plasma metoprolol concentrations and appreciable beta-blockade, estimated from exercise tachycardia, throughout the day. Fluctuations throughout the day in plasma drug concentrations and degree of beta-blockade were insignificant on the thrice-daily regimen, but they varied considerably on the single-dose regimen. Both therapeutic regimens also significantly lowered blood pressure throughout the day. Although the thrice-daily regimen again tended to produce a stronger and less fluctuating hypotensive action, the differences in hypotensive effect between the two regimens were not statistically significant. A single-dose of 300 mg of metoprolol can therefore be recommended if the only aim is to reduce blood pressure but not if a steady degree of beta-blockade is needed.
mesh_terms: D000328:Adult; D002986:Clinical Trials as Topic; D004311:Double-Blind Method; D004334:Drug Administration Schedule; D005260:Female; D006334:Heart Function Tests; D006801:Humans; D006973:Hypertension / Q000188:drug therapy*; D008297:Male; D008790:Metoprolol / Q000008:administration & dosage* / Q000097:blood / Q000627:therapeutic use; D008875:Middle Aged; D005082:Physical Exertion; D011412:Propanolamines / Q000008:administration & dosage*
chemical_list: D011412:Propanolamines; D008790:Metoprolol