Sexual Dysfunction Prescription Drugs

What is Erectile dysfunction

Erectile dysfunction (impotence; sexual dysfunction) is the inability to achieve or maintain an erection sufficient for satisfactory sexual intercourse. You may not be unable to get an erection at all, or you may lose the erection during intercourse before you are ready. In most cases, erection difficulties do not affect man's sex drive.

Successful treatment of erectile dysfunction can improve sexual satisfaction, improve overall quality of life, and relieve symptoms of anxiety and depression.

Medications for sexual dysfunction

There is a variety of treatment options for sexual dysfunction today. They range from medications and simple vacuum devices to surgery for repairing blood vessels.

Most men prefer less invasive treatments. Consequently, since the introduction of the very effective oral medications, namely phosphodiesterase type 5 (PDE-5) inhibitors, other treatment options are being used less frequently.

The development of PDE- 5 inhibitors has revolutionized the treatment of men with erection problems of all severities and etiologies. Of the current options available to treat the disease, these sexual dysfunction medications are the recommended first-line treatment.

All three medications, Viagra (Sildenafil), Levitra (Vardenafil) and Cialis (Tadalafil), are noninvasive, easily administered, very effective, and well tolerated. These medications improve the erection in nearly 80% of patients using them.

How Viagra, Levitra, and Cialis work?

PDE-5 inhibitors cause smooth-muscle relaxation in the cavernosal arteries, allowing penile vasodilation and erection in response to sexual stimulation.

Viagra, Levitra, and Cialis work by blocking an enzyme found mainly in the penis that breaks down a chemical created during stimulation that increases blood flow in the erectile bodies of the penis, which then produces erections. PDE-5 inhibitors will not have any effect without sexual stimulation.

PDE-5 inhibitors increase the hypotensive effects of nitrates, so they are not suitable for use in people taking nitrates. All three drugs must be used with caution in patients taking alpha(1)-adrenoceptors antagonists for benign prostatic hyperplasia.

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Brief Patient Guide - points to consider

Although PDE-5 inhibitors share the same mechanism of action, these drugs have some pharmacological differences that translate into differing clinical effects.

Viagra (Sildenafil citrate)

• Viagra (Sildenafil) is available on the world market since 1998, and has the longest patient experience and the most extensive data confirming its efficacy, safety and tolerability.
• Efficacy: The success rate of sildenafil amounts to an average of over 80%.
• Onset of action: 30-60 minutes.
• Duration of action is up to 4 h.
• Fatty food is known to delay the absorption of Viagra.
• Contraindicated in persons taking alpha-blockers.
• Dosage: 50 mg 1 hour before sexual activity, no more than once a day. Alternatively, Viagra may be taken 30 minutes to 4 hours before sexual intercourse. If needed, your doctor may increase your dose to 100 mg or decrease to 25 mg.
• Vision disturbances are more common after Viagra, than after other PDE-5 inhibitors. In July 2005, the U.S. Food and Drug Administration found that sildenafil could lead to vision impairment in rare cases and a number of studies have linked sildenafil use with nonarteritic anterior ischemic optic neuropathy.

Levitra (Vardenafil hydrochloride)

• Levitra (Vardenafil) was introduced in the United States in September 2003.
• Vardenafil is more potent and selective biochemically than oher drugs from this class.
• Vardenafil may be effective treatment in men for whom sildenafil (Viagra) has failed1.
• Onset of action: 25 minutes (the shortest among PDE-5 inhibitors).
• Duration of action is up to 5-6 hours, little longer than that reported for sildenafil (Viagra). According to the research data3 some persons are able to achieve and maintain an erection 8-12 hours after taking vardenafil (Levitra).
• Vardenafil is not recommended in patients taking type 1A (such as quinidine, or procainamide) or type 3 antiarrhythmics (such as sotalol, or amiodarone) while no other major limitations have been reported for tadalafil (Cialis) and sildenafil (Viagra).
• The advantage that vardenafil has over sildenafil is that it does not alter color perception, a rare side effect which occurs with sildenafil (because vardenafil does not inhibit phosphodiesterase-6).
• Vardenafil is contraindicated in patients taking alpha-blockers.
• Fatty food is known to delay the absorption of vardenafil.
• Dosage: 10 mg one hour before sexual activity. Depending on efficacy and side effects, the dose may be increased to 20 mg or decreased to 5 mg.

Cialis (Tadalafil)

• Cialis (Tadalafil) was introduced in the United States in November 2003.
• Tadalafil is unique in its longer half life, which ensures 36-hour duration of effectiveness, allowing for more flexibility to scheduled medication. This feature greatly distinguishes Cialis from its two predecessors Viagra and Levitra.
• Onset of action: 16 to 30 minutes.
  Durations of action: 36 hours, the longest acting PDE-5 inhibitor.
• In comparison studies, tadalafil (Cialis) is preferred to sildenafil (Viagra) (50/100mg) by men with sexual dysfunction, possibly because of its longer duration of action2. Higher satisfaction of patients and their partners with tadalafil is mainly due to such psychosocial benefits as decreased time concerns.
• Tadalafil is contraindicated in patients taking alpha-blockers.
• Dosage: 10 mg 1 hour before sexual activity. Depending on efficacy and side effects, the dose may be increased to 20 mg or decreased to 5 mg.
• Back pain and myalgia more often occur after tadalafil (Cialis).

Related information: Erectile Dysfunction: causes, risk factors and treatment options - physical and psychological causes, medications and herbal remedies for treatment of erectile dysfunction.

References

• 1. Hatzichristou DG, Aliotta P, Auerbach S Erectile response to vardenafil in men with a history of nonresponse to sildenafil: a time-from-dosing descriptive analysis. Clin Ther. 2005 Sep;27(9):1452-61.
• 2. Lee J, Pommerville P, Brock G, Gagnon R, Mehta P, Krisdaphongs M, Chan M, Chan J, Dickson R. Physician-rated patient preference and patient- and partner-rated preference for tadalafil or sildenafil citrate: results from the Canadian 'Treatment of Erectile Dysfunction' observational study. BJU Int. 2006 Sep;98(3):623-9.
• 3. Montorsi F, Padma-Nathan H, Buvat J, Schwaibold H, Beneke M, Ulbrich E, Bandel TJ, Porst H; Vardenafil Study Group. Earliest time to onset of action leading to successful intercourse with vardenafil determined in an at-home setting: a randomized, double-blind, placebo-controlled trial. J Sex Med. 2004 Sep;1(2):168-78
• 4. Sussman DO. Pharmacokinetics, pharmacodynamics, and efficacy of phosphodiesterase type 5 inhibitors. Journal of American Osteopathic Association. 2004 Mar;104(3 Suppl 4):S11-5.

Last updated: September, 2009