An Overview of Anabolic Steroids: Function, Health Risks, Disorders, and Legal Issues
Anabolic steroids (also called anabolic–androgenic steroids or AAS) are synthetic derivatives of the male sex hormone testosterone. They were originally developed in the 1930s to treat a variety of medical conditions—such as delayed puberty, muscle wasting diseases, anemia, and certain cancers—but today they’re most often associated with performance enhancement and body‑building.
Below is a comprehensive guide that explains how anabolic steroids work, what health problems they can cause, the disorders that arise from their misuse, and why they are regulated by law.
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1. How Anabolic Steroids Work
Feature Mechanism
Cellular Entry AAS diffuse across cell membranes because of their lipophilic nature.
Receptor Binding Inside the nucleus, steroid molecules bind to androgen receptors (AR). The hormone–receptor complex acts as a transcription factor that turns on genes involved in protein synthesis.
Protein Synthesis Gene activation upregulates proteins such as ribosomal proteins and myosin heavy chain → increased muscle mass.
Hormone Regulation Exogenous AAS can suppress the hypothalamic–pituitary–gonadal (HPG) axis, lowering endogenous testosterone and LH/FSH.
Side Effects Depending on dose & duration: virilization, gynecomastia (via aromatase), liver toxicity, cardiovascular strain, mood changes, infertility.
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3. How to Use Testosterone in the Body
3.1 Oral Testosterone
Form: Testosterone undecanoate tablets.
Absorption: Lipophilic; needs fat for absorption; variable bioavailability (~15–20%).
Half‑life: ~4–6 h after a single dose, but steady‑state is reached within 7 days of daily dosing (≈2–3 mg/kg/day).
Note: For a 5‑day experiment, you would use the shortest interval formulation (e.g., 500 mg of cypionate or undecanoate given once, then measure at day 5). The half‑life (~3 days for cypionate) means roughly ~50% remains by day 5.
2.4 Conversion to Bioactive Androgen
Conversion Rate: Approximately 30–40% of administered testosterone is aromatized or reduced to dihydrotestosterone (DHT). DHT is the active androgen that binds the androgen receptor.
Assumption for Calculations: Let’s assume a 35% conversion rate.
2.5 Estimating Serum Androgen Concentration
Step Calculation Result
Initial dose (oral) 100 mg/day –
Bioavailability 0.10 × 100 mg = 10 mg absorbed –
Conversion to active androgen 35% of 10 mg = 3.5 mg –
Daily active dose 3.5 mg/day –
Assuming steady-state and equal distribution in plasma volume (circulating blood ≈ 5 L) 3.5 mg / 5 L = 0.7 mg/L –
Thus, at steady state the estimated concentration of active androgen in the plasma would be approximately 0.7 mg/L (or 700 µg/L) after daily oral intake of a 10 mg dose.
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Caveats & Simplifications
No first‑pass metabolism – In reality, many compounds are partially metabolised before reaching systemic circulation.
Linear kinetics – The model assumes that absorption and elimination rates do not change with concentration.
Constant volume of distribution – The entire dose is assumed to be evenly distributed in a fixed plasma volume (≈ 5 L in adults).
No binding or metabolism during the half‑life – Any interactions with proteins, tissues, or enzymes are ignored.
Because these assumptions simplify reality greatly, the calculated concentrations should only serve as an illustrative estimate and not be taken as a precise prediction of pharmacokinetics for any real drug.
