Class: Erectile Dysfunction Agent
Dosage Forms. Tablet: 2.5 mg, 5 mg, 10 mg, 20 mg
Common FDA Label Indication, Dosing, and Titration.
1. Erectile dysfunction: Daily use, 2.5-5 mg po daily; As needed use, 10-20 mg po prior to anticipated sexual activity; maximum frequency is once daily
2. Pulmonary hypertension: 40 mg po daily
1. Benign prostatic hyperplasia: 5 mg po daily
MOA. Inhibition of phosphodiesterase type 5 (PDE5) by tadalafil enhances erectile function by increasing the amount of cyclic GMP. Penile erection during sexual stimulation is mediated by the release of nitric oxide (NO) from nerve terminals and endothelial cells, which stimulates the synthesis of cyclic guanosine monophosphate (GMP) in smooth muscle cells. Cyclic GMP causes smooth muscle relaxation and increased blood flow into the corpus cavernosum.
Drug Characteristics: Tadalafil
Medication Safety Issues: Tadalafil
Drug Interactions: Tadalafil
Adverse Reactions: Tadalafil
Efficacy Monitoring Parameters. Improvement in sexual functioning.
Toxicity Monitoring Parameters. Seek medical attention if severe skin rash, chest pain, erection lasting >4 h, tinnitus, dizziness, or shortness of breath.
Key Patient Counseling Points. If taking as needed, take 30 min prior to anticipated sexual activity. Do not take more frequently than once q24h.
Clinical Pearls. The choice between tadalafil, sildenafil, and vardenafil is largely one of patient preference; tadalafil may be preferred in those desiring “full-day coverage.” Sexual stimulation is required to initiate the local release of nitric oxide; the inhibition of PDE5 has no effect in the absence of sexual stimulation. Adcirca is FDA approved for pulmonary artery hypertension; Cialis is FDA approved for erectile dysfunction.