Refractory Epilepsy: Mechanisms of Pharmacoresistance

Refractory or drug-resistant epilepsy is a complex and debilitating disorder that impacts over one-third of people diagnosed with epilepsy. Many studies have suggested a variety of possible hypotheses for drug-resistant epilepsy, including the degeneration of neural networks, alterations of anti-epileptic drug (AED) targets, intrinsic severity/frequency of seizures, and genetic predisposition to pharmacoresistance. However, extensive research suggests that the overexpression of efflux protein transporters in brain tissue is the most viable hypothesis. Specifically, the overexpression of P-glycoproteins (P-gps) at the blood brain barrier proves the most compelling mechanism to discuss further. Studying the mechanisms of these transporters provides critical insight for new ways to combat pharmacoresistance. Thus, this review evaluates the co-administration of P-gp inhibitors with AEDs as a promising, yet relatively unexplored, treatment option for refractory epilepsy. This review specifically considers Tariquidar (TQD) the most promising P-gp inhibitor for refractory epilepsy treatment. This work aims to evaluate the role of P-gp overexpression in refractory epilepsy, consolidate current research about potential treatment options, and identify discrepancies or gaps in the literature related to P-gp inhibitory treatments for refractory epilepsy. It was concluded that, as a result of increased drug efflux processes at the blood brain barrier, overexpression of P-gp is the leading cause of pharmacoresistance. By inhibiting the activity of these proteins with the drug Tariquidar, an effective treatment for refractory epilepsy may become a reality.