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Effects of Yohimbine and Naltrexone on Sexual Function

This study has been completed.
Information provided by:
National Institutes of Health Clinical Center (CC) Identifier:
First received: July 31, 2002
Last updated: March 3, 2008
Last verified: April 2004

The purpose of this study is to evaluate the safety and effectiveness of the drugs yohimbine and naltrexone in treating men with erectile dysfunction (ED) (the inability to achieve or maintain penile erection for satisfactory sexual performance).

ED is a medical and psychological problem that is usually associated with increased age. Evidence suggests that specific neurotransmitter systems are involved in the regulation of sexual function. Yohimbine and naltrexone are drugs that may influence these neurotransmitter systems. This study will use different doses of yohimbine and fixed doses of naltrexone to determine their effectiveness in treating ED.

Participants in this study will be screened with a medical history, physical examination, blood and urine tests, and an electrocardiogram (ECG). The study will consist of three outpatient visists.

Condition Intervention
Erectile Dysfunction
Drug: Naltrexone HCL/ Yohimbine HCL

Study Type: Observational
Official Title: Effects of Alpha-2 Adrenergic and Opiate Receptor Blockade on Sexual Function in Healthy Male Volunteers

Resource links provided by NLM:

Further study details as provided by National Institutes of Health Clinical Center (CC):

Estimated Enrollment: 40
Study Start Date: July 2002
Estimated Study Completion Date: April 2004
Detailed Description:
Erectile dysfunction (ED) is a relevant medical and psychological problem for males, and is usually associated with increased age. There is substantial evidence available suggesting that noadrenergic and opiate transmitter systems are involved in regulation of sexual function. The objective of the present study is to evaluate the effects and safety of a potential novel treatment combination for ED consisting of both, the alpha-adrenoreceptor antagonist yohimbine, and the opiate antagonist naltrexone. The study uses a three-phase, double-blind, placebo-controlled cross-over design. Healthy, male volunteers will participate. The effects of differing dosages of yohimbine (10 mg versus 20 mg) and a fixed dose of naltrexone (50 mg) on penile tumescene and rigidity, and sexual arousal are assessed in a placebo-controlled design. The anticipated risks of the study are considered minimal in relation to the importance of our increased knowledge about regulation of physiological and psychological aspects of regulation of sexual function and dysfunction. This novel treatment combination could be later also applied to patients with ED of different origin, e.g. organic, psychogenic, and mixed causes.

Ages Eligible for Study:   Child, Adult, Senior
Sexes Eligible for Study:   Male
Accepts Healthy Volunteers:   Yes


Subjects must be medically healthy and free of mental illness, take no medication, and must report no problems with their sexual function. They are required to be sexually active, including successful penetrative sexual intercourse acts.

For assessments of sexual function before and after the study subjects are required to complete a detailed daily diary recording their erectile activity for 7 days before the first study session, and for 7 days after completion of the study.


Persons having taken antidepressant or other medications likely to alter monoamine neurochemistry or cerebrovascular and cardiovascular function within 6 months prior to the study will be excluded.

Individuals will also be excluded if they have: a) evidence for an axis I psychiatric disorder (DSM-IV criteria), b) medical or neurological illnesses likely to affect physiology or anatomy, c) a history of drug (including BZDs) or alcohol abuse within 1 year or a lifetime history of alcohol or drug dependence (DSM IV criteria), d) smokers, e) diagnosis of a sexual disorder, f) criminal history.

Persons must exhibit no or only moderate alcohol use. Persons with current or previous regular use ( more than 4 weeks) of BZDs and excessive use of alcohol (more than 8 ounces/day) in the past or presence are ineligible to participate, as such drug use confound the results.

Individuals beyond age 50 are excluded because subjects beyond age 50 have a far greater likelihood of showing subtile, albeit clinical irrelevant disturbances in erectile function.

  Contacts and Locations
Choosing to participate in a study is an important personal decision. Talk with your doctor and family members or friends about deciding to join a study. To learn more about this study, you or your doctor may contact the study research staff using the Contacts provided below. For general information, see Learn About Clinical Studies.

Please refer to this study by its identifier: NCT00042536

United States, Maryland
National Institute of Mental Health (NIMH)
Bethesda, Maryland, United States, 20892
Sponsors and Collaborators
National Institute of Mental Health (NIMH)
  More Information

Publications: Identifier: NCT00042536     History of Changes
Other Study ID Numbers: 020262
Study First Received: July 31, 2002
Last Updated: March 3, 2008

Keywords provided by National Institutes of Health Clinical Center (CC):
Sexual Function
Erectile Dysfunction
Alpha-2 Adrenoreceptor
Opiate Receptor
Male Impotence
Healthy Volunteer
Normal Control

Additional relevant MeSH terms:
Erectile Dysfunction
Sexual Dysfunction, Physiological
Genital Diseases, Male
Sexual Dysfunctions, Psychological
Mental Disorders
Narcotic Antagonists
Physiological Effects of Drugs
Sensory System Agents
Peripheral Nervous System Agents
Autonomic Agents
Adrenergic alpha-2 Receptor Antagonists
Adrenergic alpha-Antagonists
Adrenergic Antagonists
Adrenergic Agents
Neurotransmitter Agents
Molecular Mechanisms of Pharmacological Action
Urological Agents processed this record on April 27, 2017