Effects of semi-solidification of enteral nutrients on the pharmacokinetic behavior of orally administered carbamazepine in rats

Liquid Enteral Nutrients Alter the Pharmacokinetics of Orally Administered Carbamazepine in Rats

The interaction between enteral nutrients (ENs) and drugs co-administered through a nasogastric (NG) tube reportedly affects the absorption and resultant plasma concentrations of the respective drugs. However, the gastrointestinal absorption of carbamazepine (CBZ), an antiepileptic drug, co-administered with liquid ENs through an NG tube has not been clarified. In this study, we measured the recovery rate (%) of CBZ (Tegretol^® powder) passed through an NG tube when co-administered with distilled water or ENs (F2α^®, Racol^® NF, Ensure Liquid^®, and Renalen^® LP) of different compositions, frequently used in Japan. We also measured the plasma CBZ level in 26 rats after oral co-administration of CBZ with liquid ENs. The CBZ recovery rate was close to 100% in rats of all EN groups after passage through the NG tube. Furthermore, CBZ area under the plasma concentration-time curve from time zero to 9 h (AUC_0→9h) of the Ensure liquid^® group decreased compared with that of control group (P < 0.05) and Renalen^® LP group (P < 0.01). However, the AUC_0→9h of CBZ remained unchanged when co-administered with Ensure liquid^® 2 h after initial CBZ administration. In conclusion, the co-administration of CBZ with Ensure Liquid^® caused a reduction in the absorption of CBZ from the gastrointestinal tract, without adsorption on the NG tube. The administration of Ensure Liquid^® 2 h after CBZ is a way to prevent a decrease in plasma CBZ concentration. Our findings suggest that carefully monitoring the plasma levels of CBZ is necessary in co-administation with Ensure liquid^® to prevent the unintended effects of the interaction between CBZ and liquid EN.