Testosterone is the primary endogenous androgen, a steroid hormone synthesized from cholesterol in the Leydig cells of the testes (95%), and to a lesser extent in the adrenal cortex and ovaries. In the Indian pharmaceutical market, a 40mg dose is typically available as a transdermal gel or as a component of a compounded injection, primarily used for Testosterone Replacement Therapy (TRT) in adult males with hypogonadism. It exerts profound anabolic and androgenic effects by binding to and activating the androgen receptor, influencing gene transcription in target tissues.
Adult: For TRT in Hypogonadism: Transdermal gel (1% or 1.62%): 40-100mg applied once daily to clean, dry skin on shoulders, upper arms, or abdomen. Dose is titrated based on serum testosterone levels measured 2-8 hours after application. As part of IM blend (e.g., Sustanon 250 contains 40mg propionate): 250mg IM every 2-4 weeks, but the 40mg component is short-acting.
Note: Transdermal Gel: Apply to clean, dry, intact skin on shoulders, upper arms, or abdomen. Wash hands thoroughly after application. Allow site to dry before dressing. Do not apply to genitals. Cover application site if close skin-to-skin contact with another person (especially women/children) is anticipated. IM Injection: Deep intramuscular into gluteal muscle. Rotate sites. Use aseptic technique.
Testosterone enters target cells via passive diffusion. In androgen-responsive tissues (like prostate, skin), it is converted by 5α-reductase to the more potent metabolite dihydrotestosterone (DHT). Both testosterone and DHT bind to the intracellular androgen receptor (AR) in the cytoplasm, causing dissociation of heat shock proteins, dimerization, and translocation to the nucleus. The hormone-receptor complex binds to specific DNA sequences (Androgen Response Elements - AREs), regulating the transcription of androgen-dependent genes, leading to protein synthesis and cellular effects.
Pregnancy: Category X. Testosterone is contraindicated. Can cause virilization of the female fetus, including clitoromegaly and labial fusion. Women of childbearing potential must use effective contraception if a male partner is using topical testosterone (risk of transfer).
Driving: No direct effect, but patients should be cautioned about potential dizziness, headaches, or mood changes that could impair ability.
| Warfarin | Testosterone may potentiate anticoagulant effect by increasing clotting factor synthesis? Actually, it can both increase and decrease factors; more importantly, it can increase hematocrit, affecting blood viscosity. Monitor INR closely. | Major |
| Corticosteroids (e.g., Prednisolone) | Increased risk of fluid retention and edema. | Moderate |
| Insulin, Oral Hypoglycemics | Testosterone may decrease blood glucose; may alter insulin requirements. Monitor blood glucose. | Moderate |
| Cyclosporine, Tacrolimus | Testosterone may inhibit CYP3A4, potentially increasing levels of these drugs and risk of toxicity. | Moderate |
| Prostate cancer drugs (e.g., GnRH agonists) | Antagonistic effect. Contraindicated. | Major |
| ACTH or Corticosteroids | Enhanced edema. | Moderate |
Same composition (Testosterone (40mg)), different brands: