Interaction between rasagiline and Pueraria radix in in vitro models of parkinson's disease.

BACKGROUND: The management of Parkinson's disease (PD) remains challenging owing to the limitations of current therapies. Although rasagiline (RASA), a monoamine oxidase-B (MAO-B) inhibitor, offers advantages over levodopa, its efficacy as a monotherapy is moderate. Pueraria root (PR), a traditional East Asian medicine, has demonstrated neuroprotective potential against several neurodegenerative conditions. This study investigated the pharmacodynamic and pharmacokinetic interactions between RASA and PR to evaluate their potential as a combination therapy for PD. METHODS: We examined synergistic effects on MAO-B inhibition by performing MAO-B enzyme reaction assay. We measured the cell viability for evaluating the neuroprotective effects of their co-administration against 6-OHDA-induced toxicity in PC12 cells. For investigating the interaction of drug metabolism, CYP450 expressions were measured in hepatocytes using quantitative real-time polymerase chain reaction. RESULTS: Concentration-dependent studies revealed a significant synergistic inhibition of MAO-B activity when RASA and PR were co-administered at specific ratios, as confirmed by combination index analysis. Although neither of the two drugs alone provided significant neuroprotection at concentrations effective for MAO-B inhibition, their co-administration significantly increased the survival of in 6-OHDA-treated cells. Importantly, investigation of CYP450 metabolism demonstrated minimal interference between these compounds, with no significant alterations in the expression patterns of relevant CYP isoforms during co-administration. CONCLUSION: These findings suggest that the RASA - PR combination offers enhanced therapeutic potential through synergistic effects, while maintaining favourable metabolic compatibility. This study establishes a scientific foundation for integrating traditional herbal medicine with conventional pharmaceuticals in PD management, potentially allowing for reduced conventional drug dosages while improving therapeutic outcomes.