Conmy Mechanism of Action

Pharmacology: Pharmacodynamics: Benign Prostatic Hyperplasia (BPH): The symptoms associated with BPH are related to bladder outlet obstruction, which is compromised of two underlying components: a static component and a dynamic component.
Static Component is a consequence of an increase in prostate size. Over time, the prostate will continue to enlarge. However, clinical studies have demonstrated that the size of the prostate does not correlate with the severity of BPH symptoms, or the degree of urinary obstruction.
Dynamic Component is a function of an increase in smooth muscle tone in the prostate and bladder neck, leading to construction of the bladder outlet. Smooth muscle tone is mediated by sympathetic nervous stimulation of alpha-1 adrenoceptors, which are abundant in the prostate, prostatic capsule and the bladder neck. The reduction in symptoms and improvement in urine flow rates following administration of terazosin is related to relaxation of smooth muscle produced by blockade of alpha-1 adrenoceptors in the bladder neck and prostate. Because there are relatively few alpha-1 adrenoceptors in the bladder body, terazosin is able to reduce the bladder outlet obstruction without affecting bladder contractility.
Pharmacokinetics: Terazosin is rapidly and almost completely absorbed from the gastrointestinal tract after oral administration; the bioavailability is reported to be about 90%. It is metabolized in the liver; one of the metabolites is reported to possess antihypertensive activity. The half-life in plasma is approximately 12 hours. It is excreted in faeces via the bile and in the urine, as unchanged drug and metabolites. Terazosin is 90 to 94% protein bound.