Pharmacokinetics of anaesthetic drugs at extremes of body weight

Key points • The clinical effect of drugs can differ markedly in patients at extremes of weight. • Total body weight does not account for the distribution or metabolic activity of fatty tissue. • Drugs that do not usually require weight-based dosing may require adjustment at extreme weights. • Ideal or adjusted body weight is a useful measure to avoid errors in weight-based drug dosing. • Data are lacking for many drugs at extreme weights, and careful titration to effect is needed.