Avanafil, sildenafil, tadalafil, and vardenafil are phosphodiesterase type-5 inhibitors licensed for the treatment of erectile dysfunction; they are not recommended for use with other treatments for erectile dysfunction. The patient should be assessed appropriately before prescribing avanafil, sildenafil, tadalafil or vardenafil. Since these drugs are given by mouth there is a potential for drug interactions. CautionsAvanafil, sildenafil, tadalafil, and vardenafil should be used with caution in cardiovascular disease, left ventricular outflow obstruction, anatomical deformation of the penis (e.g. angulation, cavernosal fibrosis, Peyronie's disease), and in those with a predisposition to priapism (e.g. in sickle-cell disease, multiple myeloma, or leukaemia). Concomitant treatment with a phosphodiesterase type-5 inhibitor and an alpha-blocker (section 2.5.4 and section 7.4.1) can increase the risk of postural hypotension—initiate treatment with a phosphodiesterase type-5 inhibitor (at a low dose) only once the patient is stable on the alpha-blocker; see also interactions: Appendix 1 (avanafil, sildenafil, tadalafil, vardenafil). Contra-indicationsAvanafil, sildenafil, tadalafil, and vardenafil are contra-indicated in patients receiving nitrates, in patients in whom vasodilation or sexual activity are inadvisable, or in patients with a previous history of non-arteritic anterior ischaemic optic neuropathy. In the absence of information, manufacturers contra-indicate these drugs in hypotension (avoid if systolic blood pressure below 90 mmHg), recent stroke, unstable angina, and myocardial infarction. Side-effectsThe side-effects of avanafil, sildenafil, tadalafil, and vardenafil include dyspepsia, nausea, vomiting, headache (including migraine), flushing, dizziness, myalgia, back pain, visual disturbances (non-arteritic anterior ischaemic optic neuropathy has been reported—stop drug if sudden visual impairment occurs), and nasal congestion. Less common side-effects include painful red eyes, palpitation, tachycardia, hypotension, hypertension, epistaxis. Other side-effects reported rarely include syncope, hypersensitivity reactions (including rash, facial oedema, and Stevens-Johnson syndrome), and priapism. Serious cardiovascular events (including arrhythmia, unstable angina, and myocardial infarction), seizures, sudden hearing loss (discontinue drug and seek medical advice), and retinal vascular occlusion have also been reported.
