Elevation of carbamazepine plasma levels by diltiazem in rabbits: a potentially important drug interaction

The effect of diltiazem on the plasma level of carbamazepine (CBZ) was investigated in rabbits. The animals were given either CBZ alone or in combination with diltiazem and plasma samples were collected at different time intervals. The concentration of CBZ was detected using an HPLC method. Diltiazem significantly increased the area under the curve (AUC), the maximum plasma concentration (Cmax), and the elimination half-life (t1/2) of CBZ (p less than 0.05). These results suggest that a potentially harmful drug-drug interaction may occur if CBZ and diltiazem are administered concurrently.