Effects of short and medium chain fatty acids on absorption of lipophilic drugs from perfused rat intestine.

The absorption rates of griseofulvin and prednisolone were measured from solutions that were recirculated through a segment of in situ rat jejunum. When premicellar concentrations of butyric, octanoic, or dodecanoic acid were present in the perfusate, the griseofulvin absorption rate decreased while that of prednisolone increased. The fatty acids also increased the absorption rate of water from the perfusate, and the effect of butyric acid was attributed primarily to this increase. The absorption-altering effects of octanoic and dodecanoic acids could not be attributed solely to their effects on water absorption nor to their effects on the surface tension of the perfusate. The effects of octanoic and dodecanoic acids were explained by postulating different rate-limiting barriers to the absorption of prednisolone and griseofulvin.