Orthostatic hypotension: the incidence of orthostatic hypotension in placebo-controlled clinical studies was 1.2 % with silodosin and 1.0 % with placebo. Orthostatic hypotension may occasionally lead to syncope (see section 4.4).
Intraoperative Floppy Iris Syndrome (IFIS): IFIS has been reported during cataract surgery (see section 4.4).
4.9 Overdose
 Silodosin was eva luated at doses of up to 48 mg/day in healthy male subjects. The dose-limiting adverse reaction was postural hypotension. If ingestion is recent, induction of vomiting or gastric lavage may be considered. Should overdose of Urorec lead to hypotension, cardiovascular support has to be provided. Dialysis is unlikely to be of significant benefit since silodosin is highly (96.6 %) protein bound.
5. PHARMACOLOGICAL PROPERTIES
5.1 Pharmacodynamic properties
 Pharmacotherapeutic group: Urologicals, alphaadrenoreceptor antagonists, ATC code: G04CA04.
Mechanism of action
Silodosin is highly selective for α1Aadrenoreceptors that are primarily located in the human prostate, bladder base, bladder neck, prostatic capsule and prostatic urethra. Blockade of these α1Aadrenoreceptors causes smooth muscle in these tissues to relax, thus decreasing bladder outlet resistance, without affecting detrusor smooth muscle contractility. This causes an improvement of both storage (irritative) and voiding (obstructive) symptoms (Lower urinary tract symptoms, LUTS) associated with benign prostatic hyperplasia.
Silodosin has a substantially lower affinity for the α1Badrenoreceptors that are primarily located in the cardiovascular system. It has been demonstrated in vitro that the α1A:α1B binding ratio of silodosin (162:1) is extremely high.
Clinical studies
In a Phase II dose-finding, double-blind, placebo-controlled clinical study with silodosin 4 or 8 mg once daily, a greater improvement in American Urologic Association (AUA) symptom index score was observed with silodosin 8 mg (6.8±5.8, n=90; p=0.0018) and silodosin 4 mg (5.7±5.5, n=88; p=0.0355) as compared to placebo (4.0±5.5, n=83).
Over 800 patients with modera