TadalafilRx

Trade Names: Cialis, Adcirca

Drug Class: Phosphodiesterase 5 (PDE5) inhibitor

Preparations: 2.5-, 5-, 10-, 20 mg tablets

Dose: For pulmonary hypertension 40 mg once daily;  for erectile dysfunction 2.5-5 mg once daily or 5-20 mg episodically (not more than once daily) before sexual activity

Indications: Erectile dysfuntion, pulmonary hypertension, benign prostatic hypertrophy, PDE5 inhibitors also tried in Raynaud’s and for digital ulcers associated with scleroderma

Mechanism of Action: Inhibits PDE5 and thus increases cyclic GMP concentrations causing vasodilation

Contraindications: Hypersensitivity, concurrent use of any form of  nitrates, including ointment

Precautions: Potential for drug interactions

Pregnancy Risk: B

Adverse Effects
Common: Flushing, headache, dyspepsia, dizziness
Less common: Visual disturbance including color changes, allergy, rash, hearing loss, hypotension (particularly with nitrates or cytochrome P450 (CYP) 3A inhibitors), priapism

Drug Interactions
CYP3A inhibitors (strong inhibitors include clarithromycin, telithromycin, ketoconazole, itraconazole, nefazodone and many HIV drugs; moderate inhibitors include aprepitant, diltiazem, verapamil, erythromycin, fluconazole, posaconazole, voriconazole, grapefruit juice): increased  tadalafil concentrations.
Nitrates: Hypotension; avoid this combination
Alpha-1 blockers: Increased risk of hypotension

Patient Instructions: Avoid grapefruit juice; stop drug if have sudden visual or hearing loss

Comments: Small studies or  case-series suggest PDE5 inhibitors are modestly effective for  Raynaud’s  and for digital ulcers associated with scleroderma.

Clinical Pharmacology: Onset 60 minutes, half-life 15-35 h. Metabolized by CYP3A4.

Cost: $$$$$

BIBLIOGRAPHY

Roustit M, Blaise S, Allanore Y, et al.vPhosphodiesterase-5 inhibitors for the treatment of secondary Raynaud's phenomenon:systematic reviewand meta-analysis of randomised trials. Ann Rheum Dis 2013;72:1696-9. PMID: 23426043.

Tingey T, Shu J, Smuczek J, Pope J. Meta-analysis of healing and prevention of digital ulcers in systemic sclerosis. Arthritis Care Res 2013;65(9):1460-71.PMID: 23554239.