THE STABILITY OF ANTICONVULSANT DRUGS IN WHOLE-BLOOD

The stability of four commonly used anticonvulsant drugs, viz., valpro ic acid, carbamazepine, phenytoin, and phenobarbital in whole blood wa s investigated after storage at conditions simulating storage and tran sport from outlying rural clinics. Storage conditions included 24 h at 23-25 degrees C, 24 h at 37 degrees C, 48 h at 37 degrees C, and 48 h at 23-25 degrees C. Valproic acid, carbamazepine, and phenobarbital w ere stable for 48 h at both storage temperatures. Phenytoin was stable at 23-25 degrees C for 48 h. However, small but statistically signifi cant decreases in phenytoin concentrations were observed in samples th at were stored for 24 h or longer at 37 degrees C. These changes may n ot be clinically significant.