Correlation between the plasma concentration of free nicotinic acid and some of its pharmacological effects in the fasted rat after an oral dose of sorbinicate and of nicotinic acid.

D-Glucitol hexanicotinate (sorbinicate), when given orally to fasted rats, depresses the plasma free fatty acids (FFA) and triglycerides. The depression is about equal in intensity and duration to that induced by corresponding doses of nicotinic acid as such, but occurs in the presence of nicotinic acid plasma levels far lower than those obtained with nicotinic acid. In fact, sorbinicate is absorbed more slowly and more smoothly than is the case with nicotinic acid and the bioavailable nicotinic acid after oral sorbinicate administration is thought to be not more than 3--4% of the dose given. At the dose closest to that in clinical use sorbinicate exerts a more lasting effect than nicotinic acid both on FFA and on triglycerides, and at all the doses tested, contrary to nicotinic acid, sorbinicate did not induce plasma FFA rebound. This particular type of bioavailability, which differentiates sorbinicate from nicotinic acid, might explain the better effect on the plasma lipids as well as the absence of the side-effects that occur with nicotinic acid administration.