Purpose: To report the unsafe herb-drug interactions between a commercial product of noni juice and phenytoin in a human case.
Case report: A 49-year-old-male has been treated with phenytoin for epilepsy for more than ten years. In spite of his medication adherence, persistent sub-therapeutic phenytoin levels, which were sometimes from low to undetectable, with the result of having poor seizure control were noted as the noni fruit juice was co-administered daily. The possible mechanism is speculated to be due to noni juiceinduced cytochrome P-450 2C9 metabolism of phenytoin. Owing to many beneficial effects of noni juice, the patient was unwilling to accept our advice to quit taking it. Clobazam treatment was added, and with gradually reducing the amount of juice drunk over six months, the patient's epilepsy has been well controlled. Now only auras along with sometimes minor partial seizures occur, but no major attack has been reported for more than one year.
Conclusion: Phenytoin had been commonly used for seizure control worldwide and nearly half of patients with epilepsy had received complementary and alternative medicine in Taiwan. Thus, this report is significantly important for clinicians to be aware of the interaction between antiepileptic drugs and some herbs like noni juice. Moreover, as far as we know, this is a rare human case that is reported to disclose this unfavorable herb-drug interaction.