Tadalafil is a potent, selective, and reversible inhibitor of phosphodiesterase type 5 (PDE5). The 5mg daily dose formulation is primarily indicated for the treatment of Benign Prostatic Hyperplasia (BPH) with or without Erectile Dysfunction (ED). It works by increasing blood flow to specific areas, leading to relaxation of smooth muscles in the prostate, bladder, and penis. In the Indian context, it is a widely prescribed and cost-effective option for chronic management.
Adult: For BPH or ED: 5mg once daily, taken at approximately the same time each day, without regard to food or sexual activity. For on-demand ED (not for 5mg tablet): 10mg at least 30 minutes before activity; may be increased to 20mg or decreased to 5mg based on tolerance.
Note: Tablet to be swallowed whole with a glass of water. Can be taken with or without food. For the 5mg daily regimen, adherence to a fixed time is recommended for consistent effect. Do not crush or chew.
Tadalafil inhibits the enzyme phosphodiesterase type 5 (PDE5), which is responsible for the degradation of cyclic guanosine monophosphate (cGMP) in the corpus cavernosum of the penis, prostate, and bladder. Inhibition leads to increased intracellular cGMP levels. cGMP is a key mediator of nitric oxide (NO) signaling, causing smooth muscle relaxation and vasodilation.
Pregnancy: Category B (US FDA). Not indicated for use in women. No adequate and well-controlled studies in pregnant women. Use only if clearly needed.
Driving: Caution advised. May cause dizziness, vertigo, or syncope, especially with concomitant alcohol or antihypertensives. Patients should not drive or operate machinery until they know how tadalafil affects them.
| Nitrates (Nitroglycerin, Isosorbide) | Profound hypotension, potentially fatal. | Contraindicated |
| Alpha-blockers (Doxazosin, Tamsulosin, Prazosin) | Symptomatic hypotension (dizziness, lightheadedness). Tadalafil 5mg daily with alpha-blockers should be initiated only if patient is stable on alpha-blocker therapy. | Major |
| Potent CYP3A4 Inhibitors (Ketoconazole, Itraconazole, Ritonavir, Clarithromycin) | Significantly increases tadalafil exposure. For daily tadalafil, avoid concomitant use. For on-demand, max dose is 10mg every 72 hours. | Major |
| Antihypertensives | Additive hypotensive effect. | Moderate |
| Riociguat | Hypotensive synergy; contraindicated. | Contraindicated |
| Alcohol | Potentiates vasodilation and hypotensive effects, increases risk of dizziness and tachycardia. | Moderate |