Tadalafil is a selective, reversible inhibitor of phosphodiesterase type 5 (PDE5) used primarily for the treatment of erectile dysfunction (ED) and benign prostatic hyperplasia (BPH). The 10mg tablet is a commonly prescribed on-demand dose for ED, offering a longer duration of action compared to other PDE5 inhibitors. It is also used in a lower daily dose for BPH. It works by enhancing the effects of nitric oxide, leading to smooth muscle relaxation and increased blood flow in the corpus cavernosum of the penis and the prostate/bladder.
Adult: For ED (on-demand): 10mg orally, taken at least 30 minutes prior to anticipated sexual activity. Dose may be increased to 20mg or decreased to 5mg based on efficacy and tolerability. Maximum dosing frequency is once per day. For BPH/ED: 5mg once daily at approximately the same time each day.
Note: Tablet can be taken with or without food. Swallow whole with a glass of water. For on-demand use, plan sexual activity within the 36-hour window post-dose. Do not take more than one dose in a 24-hour period.
Tadalafil is a potent and selective inhibitor of cyclic guanosine monophosphate (cGMP)-specific phosphodiesterase type 5 (PDE5). During sexual stimulation, nitric oxide (NO) is released from nerve endings and endothelial cells in the corpus cavernosum. NO activates guanylate cyclase, which increases intracellular levels of cGMP. cGMP causes smooth muscle relaxation in the corpus cavernosum, allowing inflow of blood and erection. PDE5 is responsible for the degradation of cGMP. By inhibiting PDE5, tadalafil increases intracellular cGMP levels, thereby enhancing and prolonging the smooth muscle relaxant effects of NO, leading to improved erectile function.
Pregnancy: Not indicated for use in women. Category B: Animal reproduction studies have failed to demonstrate a risk to the fetus, but there are no adequate and well-controlled studies in pregnant women.
Driving: Caution is advised as tadalafil may cause dizziness, vertigo, and visual disturbances. Patients should not drive or operate machinery until they know how the medication affects them.
| Nitrates (Nitroglycerin, Isosorbide) | Profound, potentially fatal hypotension | Contraindicated |
| Alpha-blockers (Doxazosin, Tamsulosin, Alfuzosin) | Symptomatic hypotension (dizziness, lightheadedness). Tadalafil dose should not exceed 5mg daily when co-administered with alpha-blockers. | Major |
| Potent CYP3A4 Inhibitors (Ketoconazole, Itraconazole, Ritonavir, Clarithromycin) | Significantly increases tadalafil exposure (AUC). For on-demand use, maximum recommended dose is 10mg no more than once every 72 hours. Avoid daily dosing. | Major |
| Antihypertensives | Potential additive hypotensive effect | Moderate |
| Alcohol | Potential additive hypotensive effect and increased heart rate | Moderate |
| Riociguat | Hypotension | Contraindicated |