title: Assessment of the pharmacokinetic-pharmacodynamic interaction between terazosin and finasteride.
abstract: The pharmacokinetic-pharmacodynamic interaction between terazosin and finasteride was evaluated in an 18-day, parallel, open-label, randomized study. Forty-eight non-smoking, healthy, adult male volunteers entered the study. One third of the participants received terazosin alone, one third received terazosin and finasteride, and one third received finasteride alone. Multiple-dose coadministration of terazosin and finasteride did not alter the central values of steady-state pharmacokinetic parameters of either drug in a statistically significant manner. Compared with the single-agent groups, however, the group taking finasteride and terazosin had higher variability in the pharmacokinetic parameters of both drugs. Testosterone concentrations were not altered after administration of finasteride and terazosin alone or in combination. Terazosin administered alone did not affect the dihydrotestosterone concentrations. The significant reduction in dihydrotestosterone concentrations induced by administration of finasteride was not affected by coadministration of terazosin. Mean changes in blood pressure and pulse rate in these normotensive volunteers were generally slight; therefore, concurrent administration of multiple doses of terazosin and finasteride did not produce significant clinical concern.
authors.affiliation: Department of Pharmacokinetics and Biopharmaceutics, Abbott Laboratories, Abbott Park, Illinois 60064-3500, USA.
authors.forename: E E
authors.initials: EE
authors.lastname: Samara
authors.forename: B
authors.initials: B
authors.lastname: Hosmane
authors.forename: C
authors.initials: C
authors.lastname: Locke
authors.forename: C
authors.initials: C
authors.lastname: Eason
authors.forename: J
authors.initials: J
authors.lastname: Cavanaugh
authors.forename: G R
authors.initials: GR
authors.lastname: Granneman
mesh_terms: D000317:Adrenergic alpha-Antagonists / Q000009:adverse effects / Q000493:pharmacokinetics* / Q000494:pharmacology*; D000328:Adult; D019540:Area Under Curve; D001794:Blood Pressure / Q000187:drug effects; D013196:Dihydrotestosterone / Q000097:blood; D004347:Drug Interactions; D004791:Enzyme Inhibitors / Q000009:adverse effects / Q000493:pharmacokinetics* / Q000494:pharmacology*; D018120:Finasteride / Q000009:adverse effects / Q000493:pharmacokinetics* / Q000494:pharmacology*; D006207:Half-Life; D006339:Heart Rate / Q000187:drug effects; D006801:Humans; D008297:Male; D008875:Middle Aged; D011224:Prazosin / Q000009:adverse effects / Q000031:analogs & derivatives* / Q000493:pharmacokinetics / Q000494:pharmacology; D013739:Testosterone / Q000097:blood
chemical_list: D000317:Adrenergic alpha-Antagonists; D004791:Enzyme Inhibitors; D013196:Dihydrotestosterone; D013739:Testosterone; D018120:Finasteride; C041226:Terazosin; D011224:Prazosin