Tadalafil

Products

Tadalafil is commercially available in the form of film-coated tablets (Cialis, Adcirca, generics). It has been approved in many countries since 2004. Generics were registered in 2016 and came on the market in 2019. This article is related to erectile dysfunction treatment.

Structure and properties

Tadalafil (C22H19N3O4, Mr = 389.4 g/mol) exists as a white powder that is practically insoluble in water.

Effects

Tadalafil (ATC G04BE08) has vasodilatory and antihypertensive properties. It causes relaxation of smooth muscle in the corpus cavernosum and an increase in blood flow to the penis during sexual stimulation. The effects are due to inhibition of cGMP-specific phosphodiesterase type 5 (PDE-5), leading to an increase in cGMP, which mediates these effects as a second messenger of nitric oxide (NO). Tadalafil, unlike other phosphodiesterase-5 inhibitors, has a long half-life of approximately 17.5 hours.

Indication

For the treatment of erectile dysfunction in men. Tadalafil is also approved for the treatment of pulmonary arterial hypertension and is registered in some countries for the treatment of benign prostatic hyperplasia (in many countries since 2013).

Dosage

According to the SmPC. Tablets are taken 30 minutes to a maximum of 36 hours before sexual activity. The intake is a maximum of once a day. In case of regular need, daily intake of a lower dose of 2.5 to 5 mg is also possible. Administration is independent of meals.

Contraindications

  • Hypersensitivity
  • Concurrent treatment with nitrates, NO donors, or amyl nitrite.
  • Severe liver dysfunction
  • Certain cardiovascular diseases

For complete precautions, see the drug label.

Interactions

Tadalafil is a substrate of CYP3A4. Corresponding drug interactions with CYP inhibitors and inducers are possible. Tadalafil potentiates the antihypertensive effects of nitrates, NO donors, and amyl nitrite and should not be administered concomitantly. Therapy with antihypertensive agents may also lead to an increased reduction in blood pressure.

Adverse effects

The most common possible adverse effects include headache, dyspepsia, flushing, muscle pain, back pain, dizziness, lower abdominal discomfort, and nasal congestion. Other side effects include low blood pressure, cardiovascular disease, and visual disturbances.