Module 2: Basic Pharmacology of Controlled Drugs and Substances
Anabolic steroids – Pharmacokinetics
Rate of absorption and bioavailability depends upon route (oral versus injection) and formulation (e.g. lipid soluble), especially given the high first pass hepatic metabolism for most of these substances. Oral absorption of testosterone is rapid and slower for injectable forms (both subcutaneous and intramuscular). Transdermal testosterone is available in patch form and has a peak plasma time of 2-6 hours post administration and the duration of 24-48 hours. These substances are protein-bound and have a short half-life, which is influenced by the mode of administration and formulation. Elimination is primarily through urine (90%) and feces (6%).