Tadalafil

Tadalafil is a selective phosphodiesterase type 5 (PDE5) inhibitor used to treat erectile dysfunction, benign prostatic hyperplasia, and pulmonary arterial hypertension by increasing cGMP levels to promote smooth muscle relaxation and vasodilation.

Brief glance

The primary outcome is Sexual Health, but it's also used for Performance. This compound is considered a Small Molecule. It may be compounded in 503A pharmacies where allowed. It is not listed under a DEA schedule.

Overview

Tadalafil is a PDE5 inhibitor used to treat erectile dysfunction by increasing blood flow to the penis and symptoms of benign prostatic hyperplasia. Tablets vary by manufacturer and strength, typically appearing as oval or round, film-coated in yellow, orange, or white with identifying markings; branded Cialis is yellow and almond-shaped. Common strengths include 2.5mg, 5mg, 10mg, and 20mg, available as generics or branded versions.

Tadalafil is a selective inhibitor of cyclic guanosine monophosphate (cGMP)-specific phosphodiesterase type 5 (PDE5), an enzyme that degrades cGMP and plays a key role in smooth muscle relaxation. It is primarily used to treat erectile dysfunction, benign prostatic hyperplasia, and pulmonary arterial hypertension by increasing cGMP levels, which promotes vasodilation and improved blood flow in response to sexual stimulation or in pulmonary vasculature. Chemically, tadalafil is an annulated 2,5-diketopiperazine with the molecular formula C22H19N3O4 and a molecular weight of 389.41, appearing as a white to off-white powder that is practically insoluble in water. Compared to other PDE5 inhibitors like sildenafil, tadalafil offers greater selectivity for PDE5, a longer half-life enabling once-daily dosing, and minor inhibition of PDE11 whose clinical effects remain undefined. It is available in oral tablets typically containing 5, 10, or 20 mg of the active ingredient alongside common excipients.

Benefits

Tadalafil is a phosphodiesterase type 5 (PDE5) inhibitor indicated for three primary therapeutic uses: erectile dysfunction, benign prostatic hyperplasia (BPH), and pulmonary arterial hypertension (PAH).¹ For erectile dysfunction, tadalafil increases blood flow to the penis during sexual stimulation by relaxing smooth muscle in the corpus cavernosum, enabling sustained erections.¹,² In BPH, the medication alleviates lower urinary tract symptoms—including urinary hesitation, weak stream, and nocturia—through decreased smooth muscle cell proliferation and reduced inflammation in the prostate, improving urinary flow in up to 50% of patients.¹,² For PAH, tadalafil relaxes blood vessels in the pulmonary vasculature to reduce pulmonary artery pressure and improve exercise capacity, with patients experiencing a 20% increase in exercise tolerance compared to untreated controls.³,⁴ Tadalafil's extended half-life compared to other PDE5 inhibitors makes it suitable for once-daily chronic dosing, particularly beneficial in PAH management.¹ Secondary cardiovascular benefits include modest blood pressure reduction of 6 to 10 mmHg and improved endothelial function, which may reduce the risk of heart attack and stroke in susceptible populations.³

Side effects

Tadalafil, a phosphodiesterase inhibitor used to treat erectile dysfunction and benign prostatic hyperplasia, causes common side effects including headache (affecting about 15% of men at the highest 20 mg dose), back pain, muscle aches, indigestion, heartburn, facial flushing, and nasal congestion, with most of these mild to moderate effects resolving within 48 hours⁵,⁶,⁷. Back pain and muscle aches typically appear 12 to 24 hours after taking the medication and occur in roughly 1 in 20 users, with risk increasing at higher dosages⁵,⁷. Serious but rare side effects requiring immediate medical attention include priapism (erections lasting more than 4 hours), sudden vision loss, sudden hearing loss, allergic reactions with swelling of the face or throat, low blood pressure (especially when combined with other blood pressure-lowering medications or alcohol), and cardiovascular events such as heart attack or stroke⁶,⁸,⁹,¹⁰. Users should seek emergency care immediately if they experience chest pain, sudden vision or hearing loss, prolonged painful erections, severe headache, weakness on one side of the body, difficulty breathing, or swelling of the lips, mouth, or throat⁸,⁹,¹⁰. The medication works by dilating blood vessels to increase blood flow, which explains many side effects including headaches from increased cerebral blood flow and gastrointestinal effects from altered smooth muscle function⁵,¹¹.

Mechanisms of action

Tadalafil works by blocking phosphodiesterase type 5 (PDE5), an enzyme that normally breaks down cyclic guanosine monophosphate (cGMP), a molecule essential for blood vessel relaxation.¹² By inhibiting PDE5, tadalafil allows cGMP to accumulate, which causes smooth muscle cells to relax and blood vessels to dilate, increasing blood flow.¹³ For erectile dysfunction, this mechanism enables blood to fill the corpus cavernosum of the penis during sexual stimulation, producing an erection.¹² The same mechanism—increased cGMP and vascular relaxation—helps tadalafil treat pulmonary arterial hypertension by reducing blood pressure in the lungs and benign prostatic hyperplasia by relaxing prostate and bladder tissue.¹² Tadalafil's distinctive longer half-life of 17.5 hours compared to other PDE5 inhibitors allows for extended therapeutic effects and daily dosing, earning it the nickname "The Weekend Pill."¹⁴