Vardenafil Tablets—Levitra
By William T. Elliott, MD, FACP, and James Chan, PharmD, PhD
Vardenafil has been approved for the treatment of erectile dysfunction (ED) in men. The drug is the second oral type 5 phosphodiestase (PDE5) inhibitor approved for this indication along with sildenafil (Viagra). Vardenafil is manufactured by Bayer Corporation in Europe and will be distributed by GlaxoSmithKline under the trade name "Levitra." It is expected to be heavily promoted in this lucrative market.
Indications
Vardenafil is approved for the treatment of erectile dysfunction in men.
Dosage
The recommended dose is 10 mg taken approximately 60 minutes before sexual activity. The dose may be increased to 20 mg or reduced to 5 mg depending on effectiveness, side effects, or interacting drugs. Vardenafil may be taken without regard to meals. No dose adjustment is required in patients with renal impairment or mild hepatic impairment. The dose should be reduced to 5 mg in patients with moderate hepatic impairment.1 The dose should be reduced if concomitant medications include potent CYP3A4 inhibitors.
Potential Advantages
Vardenafil is more selective for the type 5-phosphodiesterase inhibitor and is more potent on a mg basis. In animal models, vardenafil produced an increase in intracavernosal pressure faster, with a higher magnitude, and with longer duration then sildenafil.2
Potential Disadvantages
The most common side effects are headache (15% vs 4% for placebo), flushing (11% vs 1%), rhinitis (9% vs 3%), and dyspepsia (4% vs 1%).1 Similar to sildenafil, the drug should not be used concomitantly with nitrates or alpha blockers since the combination may lead to hypotension and syncope. Vardenafil should also be avoided in men with prolonged QT interval syndrome because of the risk of arrhythmia.
Comments
Vardenafil is the second PDE5 inhibitor to be approved for erectile dysfunction. It appears to be more selective and more potent than sildenafil. It has been studied in 4 major double-blind, randomized, placebo-controlled, fixed-dose, multicenter studies involving 2431 study subjects.1 Efficacy has been shown in subjects with diabetes and after radical prostatectomy.1,3 Efficacy is generally assessed by Erectile Function Doman score of the International Index of Erectile Function domain score, rates of vaginal penetration, and successful intercourse. Similar to sildenafil, vardenafil is well tolerated, and side effects appeared to be similar and both have a median peak plasma concentration at 60 minutes.1,5 The PDE5 inhibitors even have similar QTc effects.4 Precautions for use and potential drug interactions are similar for these drugs. Vardenafil is priced at $9.63 per tablet (all strengths) compared to $8.10 for sildenafil.
Clinical Implications
Vardenafil provides the first competitor for sildenafil since its launch in 1998. While vardenafil appears to be more selective and more potent, no clear clinical advantage has been demonstration, as there have not been any published comparative studies. Some have suggested that vardenafil may be more effective in difficult-to-treat erectile dysfunction in diabetics;3 however, that remains to be established.
Dr. Elliott is Chair, Formulary Committee, Northern California Kaiser Permanente, and Assistant Clinical Professor of Medicine, University of California-San Francisco. Dr. Chan is Pharmacy Quality and Outcomes Manager, Kaiser Permanente, Oakland, CA. Both are associate editors of Internal Medicine Alert.
References
1. Levitra Product Information. Bayer Pharmaceuticals Corporation. August 2003.
2. Choi S, et al. J Androl. 2002;23(3):332-337.
3. Goldstein I, et al. Diabetes Care. 2003;26:777-783.
4. www.fda.gov/ohrms/dockets/ac/03/slides/3956S1_03_Bayer.ppt. (Accessed September 22, 2003).
5. Sildenafil Product Information. Pfizer Labs. November 1998.
Vardenafil has been approved for the treatment of erectile dysfunction in men. The drug is the second oral type 5 phosphodiestase (PDE5) inhibitor approved for this indication along with sildenafil (Viagra).
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