Opium → Morphine → Heroin
The opium poppy provides a striking case of progressive isolation — three distinct drugs from one plant, each step stripping more of the orchestra away and sharpening the lead instrument.
Step 1: Raw Opium — The Full Orchestra
Raw opium latex contains over 40 alkaloids. The pharmacologically notable ones:
| Alkaloid | Approx. % | What it does |
|---|---|---|
| Morphine | ~10–16% | The strongest MOR agonist in the mix. The lead. |
| Codeine | ~1–3% | Weaker MOR agonist; partly metabolized to morphine in the liver. |
| Thebaine | ~0.5–2% | Mild stimulant (no analgesia); source alkaloid for oxycodone synthesis. |
| Papaverine | ~1–2% | Vasodilator and smooth muscle relaxant. No opioid receptor binding. Offsets some of morphine's GI effects. |
| Noscapine | ~3–10% | Antitussive, weak sigma receptor binding. No MOR activity. |
Whole opium (or laudanum — opium dissolved in alcohol) delivers MOR agonism alongside papaverine's smooth-muscle relaxation, noscapine's cough suppression, and codeine's secondary contribution. The effects are blunted, spread across multiple mechanisms, and the onset is slow.
Progressive Isolation — Each Step Louder
The Pattern in Summary
Progressing from opium → morphine → heroin is progressive isolation and refinement of MOR agonism, with progressive loss of the other plant compounds. Each step also increases addictive potential — not because the receptor pharmacology changes, but because the delivery speed to the brain accelerates.
This is the orchestral principle at its clearest: same receptor, same brain region, same downstream result. What changes at each step is how fast and how purely the signal arrives. The lead instrument gets louder and faster with each round of purification. The orchestra is stripped away. What's left is more efficient at producing reward — and more efficient at producing dependence.
Applied to the current supply: Module 10.4 covered that most "heroin" in the US is now fentanyl — a synthetic opioid that bypasses the plant origin entirely. Fentanyl has no alkaloid orchestra, is ~100× more potent than morphine by analgesic potency, and is typically delivered in a way that maximizes onset speed. It is the logical endpoint of the progressive isolation described in this module.