Influence of single nucleotide polymorphism of LAT1 on therapeutic response to gabapentinoids in Pakistani patients with neuropathic pain

Mirogabalin, a novel α2δ ligand, is not a substrate of LAT1, but of PEPT1, PEPT2, OAT1, OAT3, OCT2, MATE1 and MATE2-K

Mirogabalin is a α₂δ ligand as well as pregabalin. The aim of this study was to clarify whether mirogabalin is a substrate of human LAT1, which involved in absorption and disposition of pregabalin, and to investigate transporters involved in renal secretion and absorption of mirogabalin using transporter-expressing cells and fresh human kidney slices.We employed uptake assay of [³H]mirogabalin by HEK293T or HEK293 cells transiently overexpress human OAT1, OAT3, OCT2, LAT1/4F2hc, LAT2/4F2hc, PEPT1, and PEPT2 proteins. Transport assay of MDCKII cells transiently overexpress OCT2/MATE1, and OCT2/MATE2-K proteins was conducted. Contribution of transporters to renal secretion was investigated by uptake assay using human kidney slices.Uptake clearances of [³H]mirogabalin by OAT1-, OAT3-, OCT2-, PEPT1-, and PEPT2-expressing cells were higher than that by vector cells, but by LAT1/4F2hc and LAT2/4F2hc-expressing cells were not. In transport assay using OCT2/MATE1 and OCT2/MATE2-K cells, [³H]mirogabalin showed directional transport from basolateral to apical side. Contribution of OAT1, OAT3, and OCT2 was observed by uptake of [³H]mirogabalin into the kidney slices.These results indicate that mirogabalin is not a substrate of LAT1, but of PEPT1 and PEPT2 involved in absorption and of OAT1, OAT3, OCT2, MATE1 and/or MATE2-K involved in its urinary secretion.

Lack of impact of OCTN1 gene polymorphisms on clinical outcomes of gabapentinoids in Pakistani patients with neuropathic pain

Background and objective

Gabapentinoids are the first-line drugs for neuropathic pain. These drugs are the substrate of organic cation transporter (OCTN1) for renal excretion and absorption across the intestinal epithelium. Gabapentinoids exhibit wide interindividual variability in daily dosage and therapeutic efficacy which makes titration regimens prolonged for optimal efficacy. The present study aimed to investigate the possible influence of the single nucleotide polymorphism (SNP) of OCTN1 on therapeutic efficacy and safety of gabapentinoids in neuropathic pain patients of the Pakistani population.

Methods

Four hundred and twenty-six patients were enrolled in the study. All participants were genotyped for OCTN1 rs1050152 and rs3792876 by PCR-RFLP method and followed up for eight weeks. The therapeutic outcomes of gabapentinoids, reduction in pain score, inadequate or complete lack of response, adverse events (AEs) in responders and discontinuation of treatment on account of AEs were recorded for all patients.

Results

There was no significant association of genotypes and alleles of both SNPs on the clinical response of gabapentinoids (P ˃ 0.05). Similarly, significant differences were not found in the reduction of pain scores and AEs among different genotypes in the responders. The present study has reported the association of OCTN1 rs1050152 and rs3792876 polymorphisms with clinical outcomes of gabapentinoids for the first time in the real-world clinical setting.

Conclusion

Our results suggest a lack of influence of OCTN1 genetic variants in the determination of clinical response to gabapentinoids in patients with neuropathic pain in the Pakistani population. These findings signify the role of renal functions in predicting the interindividual variability to therapeutic responsiveness of gabapentinoids.