Tadalafil

Tadalafil is one of the phosphodiesterase type 5 (PDE5) inhibitors, a small family of medicines for erection problems. By holding back this enzyme, it allows the blood vessels of the penis to relax so that they can fill properly once a man is aroused. It does not create desire, and on its own, without sexual stimulation, nothing happens. Under the UK summary of product characteristics (SmPC) it is licensed to treat erectile dysfunction in adult men, and the SmPC is clear that it is not for use by women.

The tadalafil tablets on this page are an imported generic, offered in five strengths: 10 mg, 20 mg, 40 mg, 60 mg and 80 mg. The 10, 20, 40 and 60 mg tablets come in packs of 10, 20, 30, 60, 90, 120, 180, 270 or 360; the 80 mg tablets are available in packs of 10 to 120. Of these, only 10 mg and 20 mg match doses licensed in the UK for erectile dysfunction. The 40, 60 and 80 mg strengths are above the maximum set out in the SmPC, and no UK-licensed tablet exists at those levels.

For on-demand use the recommended starting dose is 10 mg, taken at least 30 minutes before anticipated sexual activity, with or without food. If the effect is not enough, 20 mg may be tried. Whichever strength is used, it should not be taken more than once a day. Men who expect to use it at least twice a week may instead be offered a lower daily dose of 5 mg, taken at around the same time each day and reducible to 2.5 mg; neither of those strengths is sold here. With severe kidney impairment the ceiling is 10 mg and daily dosing is not advised, while men with liver problems are advised to keep to 10 mg on demand. The prescriber decides which dose, if any, is right for each patient.

In the UK, tadalafil tablets are prescription-only medicines (POM), licensed in 2.5, 5, 10 and 20 mg strengths and sold under a number of generic names. One 10 mg product has also been reclassified as a pharmacy (P) medicine, supplied in small packs once a pharmacist has assessed the man's suitability. The imported tablets offered on this page are not UK-licensed products.

The SmPC rules out any organic nitrate, including glyceryl trinitrate sprays and isosorbide tablets used for angina, because the pairing can make blood pressure fall sharply; riociguat, a medicine for pulmonary hypertension, is excluded for the same reason. It must also be avoided after a heart attack within the past 90 days or a stroke within the past six months, with unstable angina or angina that comes on during sex, with heart failure of NYHA class 2 or worse in the last six months, and with uncontrolled arrhythmia, blood pressure below 90/50 mmHg or uncontrolled hypertension. Anyone who has lost sight in one eye through non-arteritic anterior ischaemic optic neuropathy (NAION) should not take it, nor should men whose heart condition makes sexual activity inadvisable.

The liver breaks tadalafil down mainly via the enzyme CYP3A4. Ketoconazole, itraconazole, ritonavir, clarithromycin, erythromycin and grapefruit juice can push its blood levels up, whereas rifampicin, carbamazepine, phenytoin and phenobarbital can bring them down. The side effects reported most often are headache, indigestion, back pain and aching muscles, and they become more frequent as the dose rises; flushing and a blocked nose are also common. Sudden loss of sight or hearing, chest pain, or an erection lasting longer than four hours calls for urgent medical help, at A&E if need be.