Fig. 2. Compared with young patients, elderly patients tend to have more adipose tissue, decreased body water, and less muscle mass. These changes will cause water-soluble drugs to have decreased volume of distribution (Vd^water), whereas lipid-soluble drugs may have increased volume of distribution (Vd^lipid). Clearance for most drugs is decreased in the elderly. Drug sensitivity (especially to anesthetics) is usually increased in elderly patients but may be decreased for other drugs, such as β blockers.