Abstract
The effect of fasting on the oral absorption and excretion of sodium salicylate and aspirin was studied in rabbits. The attainment of the maximum blood levels of those drugs in the fasted rabbits was somewhat slower than in the nonfasted rabbits. However, the extents of absorption of those drugs were the same in the fasted rabbits as in the nonfasted rabbits. The elimination rates of sodium salicylate and aspirin in the nonfasted rabbits were markedly enhanced by the increase in the urine pH owing to the food, resulting in the decrease in the blood levels of those drugs in the nonfasted rabbits. Also, the absorption rate constant for sodium salicylate in the nonfasted rabbits, in which the elimination rate constant was almost the same with that in the fasted rabbits, was significantly greater than that in the fasted rabbits. The percent of sodium salicylate remaining in the stomach after oral administration of the drug was significantly greater in the fasted rabbits. Therefore, it is concluded that the rates of stomach emptying of sodium salicylate and aspirin in the fasted rabbit are much slower than in the nonfasted rabbit, resulting in a decrease in the gastrointestinal absorption of those drugs.
