Wafesil

What it is

Wafesil is sildenafil indicated for the treatment of erectile dysfunction in adult males. Sildenafil is an oral therapy for erectile dysfunction, which restores impaired erectile function by increasing blood flow to the penis, resulting in a natural response to sexual stimulation. The physiological mechanism responsible for erection of the penis involves the release of nitric oxide (NO) in the corpus cavernosum during sexual stimulation. NO then activates the enzyme, guanylate cyclase, which results in increased levels of cyclic guanosine monophosphate (cGMP), producing smooth muscle relaxation in the corpus cavernosum and allowing inflow of blood. Sildenafil is a potent and selective inhibitor of cGMP PDE5 which is responsible for degradation of cGMP in the corpus cavernosum.

Approved indications

— Treatment of erectile dysfunction in adult males.

Dosing overview

The recommended dose is 50 mg taken as needed approximately one hour before sexual activity. Based on the efficacy and toleration, the dose may be increased to 100 mg or decreased to 25 mg. The maximum recommended dose is 100 mg. The maximum recommended dosing frequency is once per day. Since sildenafil clearance is reduced in elderly patients, a first dose of 25 mg should be considered. Based on efficacy and toleration, the dose may be increased to 50 mg and 100 mg. Since sildenafil clearance is reduced in patients with severe renal impairment (Clcr <30 mL/min) a 25 mg starting dose should be considered. Based on efficacy and toleration, the dose may be increased to 50 mg and 100 mg. Since sildenafil clearance is reduced in patients with hepatic impairment (e.g., cirrhosis) a 25 mg starting dose should be considered. Based on efficacy and toleration, the dose may be increased to 50 mg and 100 mg.

Key safety warnings

Wafesil is contraindicated in men for whom sexual intercourse is inadvisable due to cardiovascular risk factors (e.g., patients with severe cardiovascular disease such as established cardiac failure and unstable angina pectoris). Prior to initiating any treatment for erectile dysfunction, physicians should consider the cardiovascular status of their patients, including those with recent onset angina, since there is a degree of cardiovascular risk associated with sexual intercourse. Physicians should advise patients to stop use of all PDE5 inhibitors, including sildenafil, and seek immediate medical attention in the event of a sudden loss of vision in one or both eyes. Such an event may be a sign of non-arteritic anterior ischaemic optic neuropathy (NAION), a cause of decreased vision including permanent loss of vision, that has been reported rarely post marketing in temporal association with the use of all PDE5 inhibitors. Sudden decrease or loss of hearing, which may be accompanied by tinnitus and dizziness, has been reported in a small number of post marketing and clinical trials cases with the use of all PDE5 inhibitors, including sildenafil. Most of these patients had risk factors for sudden decrease or loss of hearing. In case of sudden decrease or loss of hearing patients should be advised to stop taking sildenafil and consult a physician promptly. Prolonged erections greater than four hours in duration and priapism (painful erections greater than 6 hours) have been reported infrequently since market approval of sildenafil. In the event of an erection that persists longer than 4 hours, the patient should seek immediate medical assistance. If priapism is not treated immediately, penile tissue damage and permanent loss of potency could result. Caution is advised when sildenafil is administered to patients taking an alpha-blocker, as the co-administration may lead to symptomatic hypotension in a few susceptible individuals. In order to minimise the potential for developing postural hypotension, patients should be haemodynamically stable on alpha-blocker therapy prior to initiating sildenafil treatment.

Contraindications

Use of sildenafil is contraindicated in patients with known hypersensitivity to any component of the capsule. Nitrates and sildenafil must not be used concomitantly. Sildenafil was shown to potentiate the hypotensive effects of both acute and chronic nitrate administration and therefore, its co-administration with NO donors, organic nitrates or organic nitrites in any form, either regularly or intermittently is contraindicated. The co-administration of PDE5 inhibitors, including sildenafil, with guanylate cyclase stimulators, such as riociguat, is contraindicated as it may potentially lead to symptomatic hypotension. The safety of sildenafil has not been studied in the following sub-groups of patients and its use is therefore contraindicated until further information is available: severe hepatic impairment, hypotension (blood pressure <90/50 mmHg), hypertension (blood pressure >170/110 mmHg), recent history of stroke or myocardial infarction and known hereditary degenerative retinal disorders such as retinitis pigmentosa (a minority of these patients have genetic disorders of retinal PDEs).

Regulatory history

Wafesil was first approved on 31 July 2018. ARTG registrations for the brand Wafesil include ARTG 288496 (Wafesil 25 sildenafil citrate 25 mg sublingual wafers) and ARTG 288497 (Wafesil 50 sildenafil citrate 50 mg sublingual wafers), both first listed on 2018-06-14.