Ethanol and Alcohols

Ethanol and Alcohols

1. Definition, chemistry & scope

• Alcohols are hydroxy (–OH) derivatives of aliphatic hydrocarbons; when unqualified, "alcohol" means ethyl alcohol / ethanol (CH₃CH₂OH), a two-carbon alcohol rapidly distributed into body water and brain (KDT 8e Ch.28, pp.415–6; G&G 14e Ch.27, p.519).
• Ethanol is the oldest recreational drug and likely contributes to more morbidity, mortality and public-health cost than all illicit drugs combined; pharmacological importance is for its presence in beverages, alcoholism and intoxication rather than as a medicine (G&G 14e Ch.27, p.519; KDT 8e Ch.28, p.415).
• DSM-5 merges "alcohol abuse" and "alcohol dependence" into a single alcohol use disorder (AUD) on a mild–moderate–severe continuum; diagnosis needs ≥2 of 11 behaviours in 12 months (mild 2–3, moderate 4–5, severe 6–11 criteria). Four behavioural domains: impaired control, negative social consequences, risky use, altered physiology (tolerance/withdrawal) (G&G 14e Ch.27, p.519).
• Heritability of AUD is estimated at 50–60% by twin/family studies; alcoholism is often a familial trait, with a genetic contribution to progression from social drinking to alcoholism in ~50% of individuals (G&G 14e Ch.27, p.526; KDT 8e Ch.28, p.420).

Manufacture, beverages & other forms of alcohol

• Manufactured by fermentation of sugars by yeast zymase (C₆H₁₂O₆ → 2 CO₂ + 2 C₂H₅OH); fermentation self-inhibits at ~15% alcohol; commercial source is molasses (sugar-industry byproduct) (KDT 8e Ch.28, p.415).
• Malted liquors (beer, stout; 3–6%, strong beers up to 10%) and wines (light 9–12%, fortified 16–22%, effervescent 12–16%) are undistilled; spirits (rum, gin, whiskey, brandy, vodka) are distilled and in India standardised to 42.8% v/v (37% w/w) for licensed brands (KDT 8e Ch.28, p.415).
• Alcohol content of beverages: beer 4–6% v/v, wine 10–15%, distilled spirits ≥40%; "proof" = twice the % alcohol (US) — 40% alcohol = 80 proof. A US "standard drink" (12 oz beer / 5 oz wine / 1.5 oz shot) ≈ 14 g ethanol (density 0.79 g/mL) (G&G 14e Ch.27, p.520).
• Indian "1 drink" convention (KDT): 50 mL spirits = 150 mL wine = 400 mL beer ≈ 16 g alcohol, giving a peak BEC ~30 mg/dL on an empty stomach in an average adult male (KDT 8e Ch.28, p.420).
• Other forms: absolute alcohol (99% w/w, dehydrated), rectified spirit (90% w/w from molasses), proof spirit (49.29% w/w / 57.1% v/v), methylated/denatured (industrial) spirit = 95 parts rectified spirit + 5 parts wood naphtha (methanol), tinted blue with methylene blue to render undrinkable (KDT 8e Ch.28, p.415).