Substances: Drug Classes, Anabolic Steroids, and OTC Products
The Substances domain asks you to identify drug classes, their acute effects, dose-related harms, and the two special categories the exam returns to: anabolic-androgenic steroids and over-the-counter (OTC) products. Most items give a user profile or an adverse-effect cluster and ask for the agent, the mechanism, or the most likely complication.
Depressants, stimulants, and the rest
- Depressants - alcohol, benzodiazepines, barbiturates, GHB - potentiate GABA-A inhibition; acute risks are respiratory depression and overdose, and abrupt cessation risks seizures.
- Stimulants - cocaine blocks dopamine, norepinephrine, and serotonin reuptake; amphetamines reverse transporter direction and release transmitter - producing tachycardia, hypertension, hyperthermia, and paranoid psychosis.
- Opioids act at mu receptors; the signature triad is miosis, respiratory depression, and reduced consciousness.
- Cannabinoids act at CB1; classic hallucinogens largely at 5-HT2A; inhalants are diverse solvents linked to cardiac arrhythmia ("sudden sniffing death") and neuropathy.
Anabolic-androgenic steroids
Used for muscle mass and performance, usually in cycles and stacks. Oral 17-alpha-alkylated agents (oxymetholone, stanozolol) are hepatotoxic and can cause peliosis hepatis. Other effects include gynecomastia, testicular atrophy, acne, hypertension, dyslipidemia with low HDL, and psychiatric changes such as irritability and aggression. Dependence occurs - withdrawal brings depression, fatigue, and loss of libido - and needle sharing adds HIV and hepatitis risk.
Over-the-counter products
- Dextromethorphan at supratherapeutic doses acts as an NMDA antagonist and produces dissociation, tachycardia, and serotonin syndrome with serotonergic drugs.
- Pseudoephedrine is a regulated precursor; high doses cause hypertension and insomnia.
- First-generation antihistamines (diphenhydramine) are anticholinergic deliriants.
- Caffeine withdrawal - headache, fatigue - is a recognized DSM-5 syndrome.
Worked example
A 24-year-old bodybuilder presents with jaundice, tender hepatomegaly, elevated transaminases, acne, and testicular shrinkage. He admits to "supplements" from a gym contact. Reasoning: cholestatic hepatitis plus hypogonadal signs point to oral 17-alpha-alkylated steroids rather than alcohol (no thrombocytopenia or AST/ALT ratio above 2) or viral hepatitis alone. Both the liver injury and the testicular atrophy follow from the same class.
Traps
- Blaming liver injury on alcohol when the pattern is cholestatic and the patient is a young athlete.
- Assuming steroids cause euphoria; the mood change is more often irritability or aggression.
- Missing that OTC does not mean safe - dextromethorphan overdose mimics psychosis.