How Drugs Work — Receptors

Most drugs work by binding to RECEPTORS — specific proteins on cells that respond to chemical signals. Think of receptors as LOCKS, and drugs (or natural body chemicals) as KEYS. When the right key fits, the lock opens and triggers a response inside the cell. Drugs can be AGONISTS (mimic natural keys, activating receptors) or ANTAGONISTS (block the lock, preventing activation). Every drug has its specific target.

Examples. MORPHINE: agonist at OPIOID receptors — mimics endorphins, providing pain relief. NALOXONE: antagonist at the same receptors — blocks morphine, used for opioid overdose reversal. BETA-BLOCKERS (like metoprolol): block beta receptors that adrenaline activates — slowing heart rate, lowering blood pressure. ANTIHISTAMINES: block histamine receptors — reducing allergy symptoms. SSRIs (Prozac, Zoloft): block reabsorption of serotonin — increasing brain serotonin levels. Each drug's effect depends on which receptors it targets and where they live in the body.

Modern drug design. Researchers increasingly target SPECIFIC receptor subtypes (selective serotonin reuptake inhibitors vs less specific older antidepressants). Computer modeling predicts binding. STRUCTURAL biology shows the molecular shape of receptors. Some new drugs target previously "undruggable" proteins. Cancer therapies increasingly target specific mutations rather than killing all dividing cells. Each generation of drugs gets more precise.

Drugs are key-and-lock biochemistry. Every effect — and side effect — has a molecular explanation. Understanding receptors is understanding how medicines really work.