Effects of Testosterone Plus Dutasteride or Placebo on Muscle Strength, Body Composition and Metabolism in Transmen

Transmen who have undergone gender-affirming surgery require long-lasting treatments with androgens to maintain male phenotypic characteristics and to preserve their health. In this population the effects on muscle and the relative role of testosterone and its metabolite dihydrotestosterone (DHT) on the skeletal muscle are still largely unknown.

In this pilot study, we evaluated the effects of testosterone and DHT on muscle strength, body composition, metabolism. Also cutaneous androgenic effects such as acne and androgenetic alopecia were evaluated.

DESIGN

For this purpose, in this randomized, double-blind placebo-controlled pilot trial we treated variectomized transmen for 54 weeks with:

• Testosterone Undecanoate (TU) 1000 mg i.m. at weeks zero, six, 18, 30, 42 + a daily oral placebo pill (TU+PL)
• TU 1000 mg i.m. at weeks zero, six, 18, 30, 42 + dutasteride 5 mg/day (TU+DUT).

Prospective, phase III, randomized study design was used.

Subjects were seen every 12 weeks for safety monitoring that included evaluation of hematocrit, transaminases, alkaline phosphatases and bilirubin, creatinine, urea and serum electrolyte as potassium and sodium.

Baseline and week-54 evaluations included the following measurements:

blood drawings for measurements of: hormonal profile (serum testosterone, estradiol, luteinizing hormone and follicle-stimulating hormone, prolactin, sex hormone binding globulin, and thyroid stimulating hormone), haematocrit (Ht) and haemoglobin (Hb), glucidic and lipidic profile (fasting glucose, fasting insulin, total cholesterol, high- and low-density lipoproteins, and triglycerides), hepatic function (aspartate and alanine aminotransferases) and bone related markers (osteocalcin, parathyroid hormone, bone alkaline phosphatase and 25-hydroxyvitamin, 24h urinary excretion of calcium, potassium, magnesium and creatinine).

anthropometry: weight, measures DEXA for bone mass determination and body composition Isokinetic knee extension and flexion peak torque (PT-IKE and PT-IKF) Handgrip strength evalutation of the psychological profile with the brief Profile of Mood State (POMS) sexual life satisfaction evalutation with a Visual Analogue General Satisfaction Scale (VAS) physical examination: inspection of external genitalia (clitorides) and a visit to detect appearance of acne and gynecomastia

During the treatment phase all injections will be administered by the investigator or co-investigators for the entire study. Fasting (10 hours) blood samples will be taken (immediately before giving the injections) every time subjects come for injections (week 0, 6, 18, 30 and 42) and at the end of the treatment phase.

In the sexual and behavior questionnaire the subjects will judge their sexual activity and behavior in the period between visits. The subjects have the possibility to making additional comments about important events and disturbances.

Inclusion criteria

• Healthy transmen
• Previous bilateral gonadectomy during sex reassigning surgery
• Body Mass Index (BMI) between 20 and 29 kg/m²; (body weight in kilograms divided by body height in meters squared)
• Clinical examination without pathological findings relevant to the study
• No concomitant use of drugs known to affect the hypothalamic-pituitary-ovarian axis
• Written Consent Form
• High probability of a good compliance and termination of the study

Exclusion criteria

• Participation in another clinical trial within the 30 days preceding the first administration
• Simultaneous participation in another clinical trial
• Subjects institutionalized or imprisoned by order of the court
• Subject who compete in sports
• Subjects reporting desire to perform regular physical exercises for the duration of the study
• Serious organic or psychic disease suspected from history and/or clinical examination
• Diseases (especially tumors) that might represent an actual contraindication for testosterone
• Past or present history of thrombotic or embolic diseases
• Arterial hypertension
• Diabetes mellitus
• Acute or chronic hepatic diseases
• Manifest renal diseases with renal dysfunction
• Severe internal diseases
• Biochemical and/or hematological laboratory values beyond normal ranges unless the Investigator confirms that the deviations are of no clinical relevance
• Any indication of chronic use of drugs, alcohol, opiates or recreational drugs
• Use of any drug known to affect biotransformation of testosterone and/or progestin, e.g. chlorcycline, phenobarbital, phenylbutazone, aminophenazone within the 30 days preceding the first administration of the test medication and during the study
• Use of oral anticoagulatory drugs within the 30 days preceding the first administration of the test medication and during the study
• Any oral or transdermal hormone medication within the 12 weeks preceding the first administration and during the study
• Probability of poor compliance and termination of the study