Circadian variation in gastric emptying of meals in humans.

Circadian changes in drug absorption have been documented for several orally administered drugs in humans. To determine whether gastric emptying could account for these changes, morning (8 AM) and evening (8 PM) gastric emptying rates were measured in 16 healthy male subjects synchronized with diurnal activity and nocturnal rest. Gastric emptying half-times for the evening meal were significantly (p less than 0.001) longer for solids but not liquids when compared with morning emptying half-times. The increase in evening meal emptying time (53.6%) may account for the evening delay in reaching peak plasma concentrations documented for several drugs.