Clobazam serum by HPLC

Serum concentrations of other anticonvulsant drugs are not significantly affected by the concurrent administration of clobazam, with the exception of patients on another medicine called phenytoin whose serum concentrations can increase after the addition of clobazam. Other medicine interactions include the coadministration of certain antiepileptics like phenobarbital, phenytoin, or carbamazepine, which can result in reduced clobazam concentrations. Moreover, concurrent use of antifungal medicine, posaconazole, and clobazam may result in elevated clobazam concentrations.

Since co-administration of other medications such as phenytoin, carbamazepine, posaconazole, or phenobarbital may affect the concentrations of clobazam, patients may require dose adjustment of clobazam. This need for altering the optimum dosage in turn, necessitates therapeutic drug monitoring of clobazam and its active metabolite.

Clobazam has good absorption (1-4 hours for the immediate-release formulation) with low protein binding and marginal hepatic metabolism. The elimination of drug is through kidneys and is excreted unchanged in the urine with an elimination half-life of approximately 21 hours. However, its active metabolite known as N-desmethylclobazam (NDMCLB) has a longer half-life than the parent drug and can alter the pharmacological properties of clobazam. Therefore, for therapeutic drug monitoring, evaluation of both clobazam and its active metabolite is essential. For above reasons, HPLC method is a rapid, reproducible, simple, and sensitive test used for the evaluation of both clobazam and NDMCLB.

Treatment approach for epilepsy sometimes include increasing the dosage of clobazam, as tolerance develops. Nevertheless, an increase in adverse effects can also be seen with increased dosage may outshine its ability to control seizures.

Little changes in personality with the gradual increase in dose may go undetected over a long period. Moreover, in few cases, it becomes difficult to distinguish separate the effects of clobazam from the effects of other medications, seizures, and other neurological and psychological disorders. Therefore, conducting a clobazam serum by HPLC becomes important for these patients.