Heroin

Aliases: Dope, Smack, H, Junk, Skag, Brown

Chemical Class: Semi-synthetic opioid (diacetylmorphine) | Risk: extreme | Schedule: I

Mechanism: Prodrug rapidly converted to 6-MAM then morphine. Full agonist at mu-opioid receptors (MOR). High lipophilicity allows rapid BBB penetration. Activates descending pain inhibition pathways, releases dopamine in nucleus accumbens via VTA disinhibition.

Onset/Duration by Route

Overdose: Respiratory depression is primary cause of death. Classic triad: pinpoint pupils, unconsciousness, respiratory depression. Naloxone is the antidote (may need multiple doses with fentanyl contamination).

WARNING: Fentanyl contamination risk. Always test your supply with fentanyl test strips.

Fentanyl

Aliases: China White, Apache, Murder 8, TNT, Pressed pills

Chemical Class: Synthetic opioid (4-anilidopiperidine) | Risk: extreme | Schedule: II

Mechanism: Full mu-opioid receptor agonist. 50-100x more potent than morphine. Extremely high lipophilicity enables rapid CNS penetration. Onset is near-instantaneous IV. Analogs include carfentanil (10,000x morphine), sufentanil (500x), alfentanil.

Onset/Duration by Route

Overdose: Lethal dose as low as 2mg for opioid-naive individuals. May require MULTIPLE naloxone doses (fentanyl outcompetes naloxone at MOR). Chest wall rigidity ("wooden chest syndrome") can prevent ventilation even with naloxone.

WARNING: Fentanyl contamination risk. Always test your supply with fentanyl test strips.

Oxycodone

Aliases: OxyContin, Oxy, Percocet (with acetaminophen), Roxicodone

Chemical Class: Semi-synthetic opioid (thebaine derivative) | Risk: high | Schedule: II

Mechanism: Full mu-opioid receptor agonist with some kappa activity. Higher oral bioavailability than morphine (~60-87%). OxyContin was the extended-release formulation central to the opioid epidemic. Reformulated in 2010 with abuse-deterrent properties.

Onset/Duration by Route

Overdose: Standard opioid overdose presentation. Naloxone effective. Percocet overdose adds acetaminophen hepatotoxicity risk (>4g/day or lower with alcohol).

WARNING: Fentanyl contamination risk. Always test your supply with fentanyl test strips.

Morphine

Aliases: MS Contin, Roxanol, Miss Emma

Chemical Class: Natural opiate (Papaver somniferum alkaloid) | Risk: high | Schedule: II

Mechanism: Full mu-opioid receptor agonist (reference standard for opioid potency). Also activates kappa and delta receptors. Low oral bioavailability (~30%) due to extensive first-pass metabolism. Active metabolite M6G contributes to analgesia.

Onset/Duration by Route

Overdose: Classic opioid overdose. Naloxone reversal. M6G accumulation in renal failure can cause delayed respiratory depression.

Codeine

Aliases: Lean (with promethazine), Purple Drank, Sizzurp

Chemical Class: Natural opiate (methylmorphine) | Risk: moderate | Schedule: II-V (depends on formulation)

Mechanism: Prodrug converted to morphine by CYP2D6 (only ~10% converted). Genetic polymorphisms: ultra-rapid metabolizers (CYP2D6 *1/*2xN) produce excess morphine (overdose risk); poor metabolizers get no analgesic effect. This makes codeine unpredictable across individuals.

Onset/Duration by Route

Overdose: Ultra-rapid metabolizers at particular risk. Lean (codeine + promethazine) adds anticholinergic and respiratory depression. Promethazine potentiates sedation.

Methadone

Aliases: Dolophine, Done, Methadose

Chemical Class: Synthetic opioid (diphenylpropylamine) | Risk: high | Schedule: II

Mechanism: Full mu-opioid agonist + NMDA receptor antagonist (unique). Extremely long, variable half-life (15-60 hours, mean ~24h). Accumulates with repeated dosing. QTc prolongation risk (torsades de pointes). Used in MAT: provides stable opioid levels preventing withdrawal and blocking euphoria from other opioids.

Onset/Duration by Route

Overdose: Long half-life means overdose can occur DAYS into treatment as drug accumulates. Requires prolonged naloxone infusion. QTc monitoring essential.

Buprenorphine

Aliases: Suboxone (with naloxone), Subutex, Sublocade (injectable), Zubsolv

Chemical Class: Semi-synthetic opioid (thebaine derivative) | Risk: moderate | Schedule: III

Mechanism: Partial mu-opioid agonist with ceiling effect on respiratory depression (safer in overdose than full agonists). Kappa-opioid antagonist (may help with dysphoria/depression). Very high receptor affinity but low intrinsic activity. Ceiling effect: increasing dose beyond ~32mg provides no additional effect. Suboxone contains naloxone to deter IV misuse (naloxone is inactive sublingual but active IV).

Onset/Duration by Route

Overdose: Ceiling effect on respiratory depression makes isolated buprenorphine overdose rare. Combined with benzodiazepines or alcohol can still be fatal. Precipitated withdrawal occurs if given to someone with full agonist in system (must be in mild withdrawal before induction).

Kratom

Aliases: Mitragyna speciosa, Biak, Ketum, Thom

Chemical Class: Plant alkaloid (mitragynine, 7-hydroxymitragynine) | Risk: moderate | Schedule: None (unscheduled federally, some state bans)

Mechanism: Mitragynine is a partial mu-opioid agonist and alpha-2 adrenergic agonist. 7-hydroxymitragynine is a more potent MOR agonist. At low doses, stimulant-like (adrenergic). At higher doses, opioid-like (sedation, analgesia, euphoria). Also has serotonergic activity.

Onset/Duration by Route

Overdose: Deaths attributed to kratom typically involve co-ingestants. Isolated kratom fatality is debated but reported. Seizures reported at high doses. FDA has issued multiple warnings.