The term “impotence” has traditionally been used to signify the inability of the male to attain and maintain erection of the penis sufficient to permit satisfactory sexual intercourse. Impotence, in most circumstances, is more precisely referred to as erectile dysfunction as this term differentiates itself from loss of libido, premature ejaculation, or inability to achieve orgasm. 1

An estimated 10 to 20 million men suffer from erectile dysfunction. This number is expected to increase dramatically as the median age of the population increases. Currently, erectile dysfunction is thought to affect over 25% of men over the age of 50. 1,2

Although the frequency of erectile dysfunction increases with age, it must be stressed that aging itself is not a cause of impotence. Although the amount and force of the ejaculate as well as the need to ejaculate decrease with age, the capacity for erection is retained. Men are capable of retaining their sexual virility well into their 80’s.

Erectile dysfunction may be due to organic or psychogenic factors. In the overwhelming majority of cases the cause is organic, i.e., it is due to some physiological reason. In fact, in men over the age of 50, organic causes are responsible for erectile dysfunction in over 90%. 3 In the past, a man with impotence who was able to have nighttime or early morning erections was thought to have psychogenic impotence. However, it is now recognized that this is not a reliable indicator. 2

Yohimbine

The only FDA approved medicine for impotence is yohimbine - an alkaloid isolated from the bark of the yohimbe tree (pausinystalia johimbe) native to tropical West Africa. Yohimbine hydrochloride increases libido, but its primary action is to increase blood flow to erectile tissue. Yohimbine is a selective alpha-2 receptor antagonist. Contrary to a popular misconception, yohimbine has no effects on testosterone levels.

When used alone, yohimbine is successful in 34% to 43% of cases. 4,5 It is effective in both psychogenic and organic causes of impotence. The standard dose of yohimbine is 15 to 20 mg per day, however, higher doses, up to 42mg of yohimbine, may prove to be more effective.

To illustrate the benefits to be expected in clinical practice, let’s examine the results from one of the more recent double-blind studies. In the study, 82 men with erectile dysfunction selected from a Veterans Administration population with a high incidence of diabetes and vascular disease underwent a multifactorial evaluation, including determination of penile brachial blood pressure index, cavernosography, sacral evoked response, testosterone and prolactin determination, sexual dysfunction inventory and arousal test.

After one month of treatment with a maximum of 42.0 mg oral yohimbine hydrochloride daily 14% of the patients experienced restoration of full and sustained erections, 20% reported a partial response to the therapy and 65% reported no improvement. In comparison, only three patients reported a positive effect in the placebo group. Maximum effect with yohimbine takes two to three weeks to manifest itself. Yohimbine was active in some patients with arterial insufficiency and a unilateral sacral reflex arc lesion, and in one with low serum testosterone levels. The 34% response is somewhat encouraging given the study population.

Side effects often make yohimbine very difficult to utilize. Yohimbine can induce anxiety, panic attacks, and hallucinations in some individuals. Other side effects include elevations in blood pressure and heart rate, dizziness, headache, and skin flushing. Yohimbine should not be used in individuals with kidney disease, women, and individuals with psychological disturbances

Although crude yohimbe bark preparations are available commercially, use of pure yohimbine hydrochloride is preferred. There are no commercial sources of yohimbe bark that are available to physicians or in health food stores which actually state the level of yohimbine per dosage. Without knowing the content of yohimbine, it is virtually impossible to prescribe an effective and consistent dosage. Because of the yohimbine content of yohimbe bark, the FDA classifies yohimbe as an unsage herb.

Muira puama

Preliminary research indicates one of the best herbs to use for erectile dysfunction or lack of libido may be Muira puama (also known as potency wood). This shrub is native to Brazil and has long been used as a powerful aphrodisiac and nerve stimulant in South American folk medicine. 6 A recent study has validated its safety and effectiveness in improving libido and sexual function in some patients.

At the Institute of Sexology in Paris, France, under the supervision of one of the world’s foremost authorities on secual function, Dr. Jacques Waynberg, a clinical study with 262 patients complaining of lack of secual desire and the inability to attain or maintain an erection demonstrated Muira puama extract to be effective in many cases. 7 Within two weeks, at a daily dose of 1 to 1.5 grams of the extract (4:1), 62% of patients with loss of libido claimed that the treatment had dynamic effect while 51% of patients with “erection failures” felt that Muira puama was of benefit. These results are extremely promising and seem to indicate that Muira puama may provide better results that yohimbine without side effects.

Presently, the mechanism of action of Muira puama is unknown. From the preliminary information, it appears that it works on enhancing both psychological and physical aspects of sexual function. Future research will undoubtedly shed additional light on this extremely promising herb for erectile dysfunction.

References:

1. NIII Consensus Conference Panel on Impotence: Impotence, JAAAMA 270:83-90, 1993

2.  Lener SE.Melnum A and Chost GJ: a review of erectile dysfunction: New insights and more questions. Journal of Urology 149:1216-55, 1993

3.  Morley JF. Management of impotence. Postgraduate Medicine 93:65-72, 1991.

4.  Susset JG, et al: Effect of yohimbine hydrochloride on erectile impotence: A double-blindstudy. J. Urology 141:1360-3, 1989.

5.  Moreales A, et al: Is yohimbine effective in the treatment of organic impotence? Results of a controlled trial. J.Urology 137:1168-72, 1987.

6.  Duke JA: Handbook of Medicinal Herbs. CRC Press, Boca Raton, FL 1985.

7.  Waynberg J: Aphrodisiacs: Contributions to the clinical validation of the traditional use of Psychopetalum guyanna. Presented at The First International Congress on Ethnopharmacology, Strasbourg, France June 5-9, 1990 (Susset JG et al. Effect of Yohimbine hydrochloride on erectile impotence, a double-blind study. J. Urol 141(6):1360-3, 1989. 6

CAUSES OF IMPOTENCE

Organic (85%)

     Vascular insufficiency

             Atherosclerosis

             Pelvic  surgery

             Pelvic trauma

             Venous shunting

     Drugs

             Antihistamines

             Antihypertensives

             Anticholinergics

             Antidepressants

             Antipsychotics

             Tranquilizers

             Others

     Alcohol and tobacco

     Endocrine disorders

             Diabetes

             Hypothyroidism

             Decreased male sex                                    hormones

             Elevated prolactin levels

             High serum estrogen levels

     Diseases or trauma to male

      sexual organs

             Diseases of the penis

             Prostate disorders

      Neurological diseases

             Pelvic trauma

             Pelvic surgery

             Multiple sclerosis

Psychologic (10%)

       Psychiatric Illness

             Stress

             Performance anxiety

             Depression

Unknown (5%)