Smith O B, Longe R L, Altman R E, Price J C
Veterans Administration Medical Center, Department of Pharmacy, Augusta, GA 30910.
Am J Hosp Pharm. 1988 Feb;45(2):365-8.
The recovery of phenytoin from solutions of intact protein components of enteral nutrition products was studied. Diluted phenytoin oral suspension was added to 10 1-mL samples of solutions of sodium caseinate, calcium caseinate, a mixture of sodium and calcium caseinates, and calcium chloride as well as to 10 1-mL samples of a distilled water control to produce theoretical concentrations of 10 micrograms/mL. The samples were filtered using an ultrafiltration technique and assayed for phenytoin concentration by high-performance liquid chromatography. The mean concentration of phenytoin in the filtrates of the test samples was significantly lower than the mean concentration in the control samples. The recovery of phenytoin from sodium caseinate solutions was significantly lower than that from solutions of calcium caseinate or calcium chloride. There was no significant difference between recovery of phenytoin from sodium caseinate solutions and that from solutions of sodium and calcium caseinates. Decreased phenytoin absorption from enteral nutrient solutions in vitro may be associated with the presence of caseinate salts and calcium chloride. However, this relationship cannot be extrapolated to in vivo absorption.
