Analgesics (pain relief without loss of consciousness):

• Non-narcotic: Aspirin (acetylsalicylic acid — inhibits cyclooxygenase → blocks prostaglandin synthesis → anti-inflammatory + anti-pyretic + analgesic). Ibuprofen, paracetamol (acetaminophen).
• Narcotic: Morphine, codeine, heroin (diacetylmorphine). Bind opioid receptors in brain. Addictive. Heroin is most dangerous (high lipid solubility → crosses blood-brain barrier fast).

Antibiotics (kill or inhibit bacteria):

• Bactericidal (kill): Penicillin (inhibits cell wall synthesis — bacteria burst), aminoglycosides.
• Bacteriostatic (inhibit growth): Tetracycline (inhibits protein synthesis), erythromycin, chloramphenicol.
• Broad-spectrum: Active against many bacterial types (tetracycline). Narrow-spectrum: Specific (penicillin G mainly gram-positive).

Antiseptics vs Disinfectants (same chemicals, different application):

• Antiseptic: Applied to LIVING tissue. Dettol (chloroxylenol), iodine tincture, boric acid, hydrogen peroxide.
• Disinfectant: Applied to NON-LIVING surfaces. Phenol (1% solution), chlorine (water treatment), SO2 (room fumigation).