Tadalafil

How it works

It selectively inhibits phosphodiesterase type-5, increasing cyclic GMP and enhancing nitric-oxide-mediated smooth muscle relaxation in the corpus cavernosum and lower urinary tract.

Prescribing in practice

• Co-administration with any nitrate or nicorandil is contraindicated because of the risk of profound, potentially fatal hypotension.
• Caution with alpha-blockers and other antihypertensives owing to additive blood-pressure lowering, and avoid in recent cardiovascular events or unstable angina.
• Dose adjustment or avoidance applies in severe renal or hepatic impairment and with potent CYP3A4 inhibitors.

Monitoring

Assess cardiovascular fitness for sexual activity before starting and review efficacy and tolerability, including any postural symptoms.

Counselling the patient

• Do not use with nitrate medicines or recreational nitrates ('poppers').
• Seek urgent care for a painful erection lasting several hours or for sudden visual or hearing loss.

Evidence & guidelines

Randomised trials support PDE5 inhibitors as first-line oral therapy for erectile dysfunction and demonstrate symptomatic benefit in benign prostatic hyperplasia.