American Board of Professional Psychology (ABPP) Practice Exam

Opioids are a class of drugs that act on the brain’s opioid receptors to alter pain, mood, and reward. Heroin and morphine are classic members of this group: morphine is a natural opioid derived from opium, and heroin is a semi-synthetic opioid chemically related to morphine. Their primary effects come from activating mu opioid receptors, producing powerful analgesia and euphoria, which is the hallmark of opioids.

Cocaine is a stimulant that boosts dopamine and other monoamines by blocking their reuptake. MDMA is an entactogen/psychedelic that increases serotonin, dopamine, and norepinephrine release. Nicotine acts on nicotinic acetylcholine receptors and has stimulant effects. None of these share the same receptor-based mechanism or clinical profile as opioids, so opioids are the correct class for heroin and morphine.