Tadalafil

Tadalafil is a PDE5 inhibitor, in the same family as sildenafil but known for acting over a longer stretch of time. When a man is sexually excited, the penis releases nitric oxide, which raises the messenger cGMP and relaxes the muscle in its blood vessels. PDE5 breaks cGMP down, and tadalafil holds that enzyme back, so an erection becomes possible. Without stimulation it does nothing, and it does not raise desire. Besides erectile dysfunction, UK products with the same ingredient treat benign prostate enlargement (5 mg) and pulmonary arterial hypertension (20 mg), so check which of these is on the box.

The listing runs 10, 20, 40, 60 and 80 mg, in counts from 10 to 360 tablets (the 80 mg stops at 120). British erectile dysfunction products come in 2.5, 5, 10 and 20 mg only. Doses of 40, 60 and 80 mg exceed the UK-licensed maximum dose for erectile dysfunction. For erectile dysfunction, the maximum recommended dose is 20 mg, taken no more than once daily; higher doses increase adverse effects.

The recommended on-demand dose is 10 mg at least 30 minutes before sexual activity, and it can go to 20 mg if 10 mg does not work well enough. A second dose within the same 24 hours is not allowed. A once-daily schedule of 2.5 mg or 5 mg at about the same time each day is licensed separately. Severe kidney impairment caps the dose at 10 mg. Food and alcohol in moderation do not stop it acting, though heavy drinking can lower blood pressure and blunt the response.

Tadalafil is contraindicated in anyone using nitrates, including GTN spray or isosorbide tablets; if nitrates are essential in a life-threatening emergency, at least 48 hours must have elapsed after the last tadalafil dose, with close medical supervision. Riociguat is excluded as well. The SmPC bars it after a heart attack in the previous 90 days, a stroke in the previous six months, heart failure of NYHA class 2 or worse in the past six months, unstable angina or angina during sexual intercourse, uncontrolled arrhythmias, blood pressure under 90/50 mmHg, uncontrolled high blood pressure, and loss of sight in one eye from NAION.

Take care with Peyronie’s disease or other penile deformity, sickle cell disease, myeloma or leukaemia, which can make priapism more likely. Strong CYP3A4 inhibitors such as ketoconazole, itraconazole and ritonavir, and inducers like rifampicin, change how much tadalafil is in the blood. Alpha-blockers can combine with it to lower blood pressure, so the prescriber may start with a low dose. Ask a prescriber before any new medicine.

Headache, indigestion, back and muscle ache, flushing and a blocked nose are common. An erection lasting four hours or more calls for emergency treatment, and so does a sudden loss of vision or hearing. Tadalafil for erectile dysfunction is a prescription-only medicine, although some 10 mg products are classed as pharmacy medicines, so the category follows the particular pack. These tablets are imported generics, not UK-licensed products, so the label on your own pack is what counts. Your doctor or prescriber will advise on the right strength and whether it is safe for you.