The Effect of 5-Alpha Reductase on Testosterone in Men

November 4, 2005 updated by: Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD)

The Role of 5-Alpha Reductase in Mediating Testosterone Actions

The enzyme 5-alpha reductase is present in small amounts in muscle and converts testosterone to dihydrotestosterone (DHT). Testosterone affects lean body tissue, muscle size, muscle strength, and sexual function in men. This study will evaluate how 5-alpha reductase influences the effects of testosterone in young healthy men.

Study Overview

Status

Unknown

Conditions

Intervention / Treatment

Detailed Description

Testosterone, the predominant circulating androgen in men, serves as the active hormone in some target tissues; however, testosterone effects in other target organs require its conversion to two active metabolites, estradiol 17-beta and DHT. The role of 5-alpha reductase in mediating testosterone's effects on muscle and sexual function remains unclear. This study will determine whether 5-alpha reduction of testosterone to DHT is necessary for mediating effects on fat-free mass, muscle size, muscle strength, and leg power in men. The study will also evaluate the necessity of 5-alpha reductase for maintenance of androgen effects on sexual function (sexual desire, overall sexual activity, nocturnal penile tumescence [NPT], response to visual erotic stimulus, and penile rigidity) in men.

Participants in this study will be treated with a drug to suppress endogenous testosterone production. Participants will then be randomly assigned to receive either testosterone and placebo or testosterone and the 5-alpha reductase inhibitor dutasteride. Testosterone will be administered weekly; dutasteride and placebo will both be administered daily. Diet and exercise will be standardized across both groups. Participants will be assessed at study entry and Week 20. Assessments will include measurements such as a DEXA scan, MRI scan, and muscle performance and sexual function tests. Participants will also have blood tests for safety monitoring; blood tests will include measures of hematocrit, liver enzymes (AST and ALT), prostate specific antigen (PSA), and cholesterol.

Study Type

Interventional

Enrollment

184

Phase

  • Phase 3

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Locations

  • United States
    • California
      • Los Angeles, California, United States, 90059
        • Recruiting
        • Charles R. Drew University
        • Contact:
          • Shalender Bhasin, MD
          • Phone Number: 323-563-9353

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

19 years to 38 years (Adult)

Accepts Healthy Volunteers

No

Genders Eligible for Study

Male

Description

Inclusion Criteria

  • General good health and capable of undergoing strength testing
  • Normal testosterone (300-1100 ng/dL), LH, and FSH levels

Exclusion Criteria

  • Currently participating in competitive sports
  • Mental state that would preclude complete understanding of the protocol and compliance
  • Disorder known to cause or be associated with hypogonadism (e.g., pituitary tumors, hyperprolactinemia, HIV infection, or Klinefelter's Syndrome)
  • More than 20% over ideal body weight
  • Disabilities that would prevent participation in strength testing (e.g., amputation of limbs, blindness, severe arthritis, angina, or neurologic disorders such as Parkinson's disease, stroke, or myopathy)
  • Uncontrolled hypertension, diabetes, congestive heart failure, or chronic obstructive lung disease
  • Alcohol or drug dependence in the 6 months prior to study entry
  • Disorders that might be exacerbated by androgen treatment (e.g., benign prostatic hyperplasia or prostate cancer, erythrocytosis [hematocrit > 51% at baseline], or sleep apnea assessed by Berlin's questionnaire)
  • Serum PSA levels > 4 microg/L
  • AST, ALT, or alkaline phosphatase elevation greater than three times the upper limit of normal
  • Creatinine greater than 2 mg/dL
  • Medications that might affect muscle or bone metabolism (e.g., glucocorticoid, rhGH, androgenic steroids, oral androgen precursors such as androstenedione or DHEA) or androgen metabolism, action, or clearance (e.g., dilantin, phenobarbitol, aldactone, flutamide, finasteride)

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Treatment
  • Allocation: Randomized
  • Interventional Model: Parallel Assignment
  • Masking: Double

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD)

Investigators

  • Principal Investigator: Shalender Bhasin, MD, Charles R. Drew University

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start

August 1, 2003

Study Completion

June 1, 2005

Study Registration Dates

First Submitted

October 7, 2003

First Submitted That Met QC Criteria

October 9, 2003

First Posted (Estimate)

October 10, 2003

Study Record Updates

Last Update Posted (Estimate)

November 7, 2005

Last Update Submitted That Met QC Criteria

November 4, 2005

Last Verified

October 1, 2003

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • R01HD043348-01 (U.S. NIH Grant/Contract)

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

Clinical Trials on Sex Disorders

Clinical Trials on testosterone enanthate

Search Similar Trials

Sponsors and Collaborators

Medical Conditions

Drug Interventions

CROs by country

CROs in Chile

Conditions

Rare Diseases

Drug Interventions

Dietary Supplements

Sponsor/Collaborators

Locations

3
Subscribe