Tadalafil

Also known as: tadalafil, Cialis (branded), PDE5 inhibitor

Sexual Well-Being

In plain English

Tadalafil is a medicine for erectile dysfunction that improves blood flow to the penis when a man is sexually aroused. It works for up to 36 hours, so it can be taken as needed or in a small daily dose. It is FDA-approved and taken by mouth. It must not be combined with nitrate heart medicines.

The science

Tadalafil is a phosphodiesterase type 5 (PDE5) inhibitor that blocks breakdown of cGMP in penile smooth muscle, enhancing nitric-oxide-mediated vasodilation and erection during sexual stimulation. Its distinguishing feature is a ~17.5-hour half-life, enabling both on-demand and once-daily dosing; randomized placebo-controlled trials (Porst 2006 and others) confirm efficacy and tolerability of 2.5-5 mg once daily and higher on-demand doses, and it is a first-line therapy in the AUA erectile-dysfunction guideline. Tadalafil is also FDA-approved for benign prostatic hyperplasia symptoms and pulmonary arterial hypertension. Absolute contraindication with nitrates and caution with alpha-blockers and guanylate cyclase stimulators (riociguat) due to hypotension; common effects are headache, flushing, dyspepsia, back pain/myalgia, and rare visual/hearing changes. FDA-approved tablets exist; compounded troches, SR capsules, and nasal sprays are not FDA-approved formulations.

References

• Porst et al., Eur Urol 2006 (once-daily tadalafil RCT)
• Burnett et al., J Urol 2018 (AUA Erectile Dysfunction Guideline)