Last updated: October 24, 2014

Trade Names: Levitra, Staxyn

Drug Class: Phosphodiesterase 5 (PDE5) inhibitor

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

Dose: For erectile dysfunction 10 mg (range 5-20  mg) approximately 1 hour before sexual activity

Indications: Erectile dysfunction; 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 vardenafil 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 3-6 h. Metabolized by CYP3A4.

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.

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