opioids.

Side effects & contraindications10 min read

Why prescribed drugs fail urine drug screens

Immunoassays detect a molecular shape, not a named drug. Which prescribed drugs cross-react, why, and the benzodiazepine trap that runs the other way.

Exam traps: X vs Y9 min read

Morphine vs codeine: why CYP2D6 decides which works

Codeine is a prodrug activated by CYP2D6, morphine is not. Poor and ultra-rapid metabolisers, and the exam trap.

Mechanisms, explained simply9 min read

Opioid-induced constipation: mechanism and peripherally acting antagonists 2026

Mu-receptor gut mechanism, why tolerance does not develop, and PAMORA antagonists.

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