Molecule

Drug Groups

approved; investigational

Description

Alfuzosin (INN, provided as the hydrochloride salt) is an alpha-adrenergic blocker used to treat benign prostatic hyperplasia (BPH). It works by relaxing the muscles in the prostate and bladder neck, making it easier to urinate. [Wikipedia]

Indication

For the reduction of urinary obstruction and relief of associated manifestations (eg. sensation of incomplete bladder emptying or straining, urgency, interrupted or weak stream) in patients with symptomatic beningn prostatic hyperplasia.

Pharmacology

Alfuzosin is a quinazoline-derivative alpha-adrenergic blocking agent used to treat hypertension and benign prostatic hyperplasia. Accordingly, alfuzosin is a selective inhibitor of the alpha(1) subtype of alpha adrenergic receptors. In the human prostate, alfuzosin antagonizes phenylephrine (alpha(1) agonist)-induced contractions, in vitro, and binds with high affinity to the alpha1a adrenoceptor, which is thought to be the predominant functional type in the prostate. Studies in normal human subjects have shown that alfuzosin competitively antagonized the pressor effects of phenylephrine (an alpha(1) agonist) and the systolic pressor effect of norepinephrine. The antihypertensive effect of alfuzosin results from a decrease in systemic vascular resistance and the parent compound alfuzosin is primarily responsible for the antihypertensive activity.

Toxicity

Side effects are dizziness (due to postural hypotension), upper respiratory tract infection, headache, and fatigue.

Affected Organisms

Biotransformation

Hepatic. Alfuzosin undergoes extensive metabolism by the liver, with only 11% of the administered dose excreted unchanged in the urine. Alfuzosin is metabolized by three metabolic pathways: oxidation, O-demethylations, and N-dealkylation. The metabolites are not pharmacologically active. CYP3A4 is the principal hepatic enzyme isoform involved in its metabolism.

Absorption

Absorption is 50% lower under fasting conditions

Half Life

10 hours

Protein Binding

82%-90%

Elimination

Following oral administration of 14C-labeled alfuzosin solution, the recovery of radioactivity after 7 days (expressed as a percentage of the administered dose) was 69% in feces and 24% in urine.

Distribution

* 3.2 L/kg [healthy male middle-aged volunteers]

References

External Links