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The role of organic cation transporter 2 inhibitor cimetidide, experimental diabetes mellitus and metformin on gabapentin pharmacokinetics in rats

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Author(s):
Jhohann Richard de Lima Benzi
Total Authors: 1
Document type: Master's Dissertation
Press: Ribeirão Preto.
Institution: Universidade de São Paulo (USP). Faculdade de Ciências Farmacêuticas de Ribeirão Preto (PCARP/BC)
Defense date:
Examining board members:
Amanda Martins Baviera; Jonas Augusto Rizzato Paschoal; Rosangela Gonçalves Peccinini
Advisor: Natalia Valadares de Moraes; Amanda Martins Baviera
Abstract

The organic cation transporter 2 (OCT2), expressed on the basolateral membrane of the proximal kidney tubule, promotes the elimination of endogenous compounds and various drugs in clinical use. Gabapentin (GAB), an anticonvulsant used to treat neuropathic pain, is eliminated primarily by renal excretion, and studies suggest participation of active secretion via OCT2. Experimental data observed in mice with streptozotocin (STZ) induced experimental diabetes mellitus (EDM) suggest that hyperglycemia and/or reduction of circulating insulin levels reduce OCT2 expression. The aim of the study is to investigate the influence of EDM, EDM after insulin administration, cimetidine (OCT2 inhibitor) and metformin (OCT2 substrate) on the kinetic dispostion of GAB in rats. Male Wistar rats were divided into five groups: control, cimetidine (single dose of cimetidine 100 mg/kg intraperitoneally), diabetic (single dose of STZ 40 mg/kg intravenously), diabetic treated (single dose of STZ 40 mg/kg intravenously and 2 IU twice daily for 15 days) and metformin (single dose metformin 100 mg/kg). All animals received a single dose of GAB (50 mg/kg, via gavage). Plasma and urine samples were collected up to 12 hours after GAB administration. Plasma and urine concentrations of GAB were determined by high performance liquid chromatography with detection by mass spectrometry and ultraviolet, respectively. The area under the plasma concentration versus time-extrapolated to infinity (ASC0-?) curve of GAB was calculated by the Gauss-Laguerre quadrature. Single dose administration of 50 mg/kg GAB in male Wistar rats resulted in values (mean ± standard deviation) of ASC0-?, Cmax, Tmax, CLT / F, T1/2, CLr and Fel of 96.31 ± 12.28 ?g.h/mL, 24.75 ± 9.26 ?g/mL, 3.66 ± 1.11 h, 0.52 ± 0.07 L/h.kg, 0.25 ± 0.07 L/h.kg and 0.48 ± 0.13, respectively. The kinetic disposition of GAB was not altered after the simultaneous administration of cimetidine or metformin. The diabetic group had higher Fel values when compared to the control group (0.83 ± 0.25 × 0.48 ± 0.13, respectively). The Diabetic Group treated with insulin also had higher Fel (0.85 ± 0.10) and CLr when compared to the control group (0.55 ± 0.10 L/hr.kg × 0.25 ± 0.07 L/hr.kg). The differences found may be explained by glomerular hyperfiltration induced by diabetes and by insulin treatment, due to increased renal blood flow. We concluded that the active transport by OCT2 is not relevant for the GAB kinetic disposition. Glomerular hyperfiltration induced by EDM and by insulin administration suggest that glomerular filtration is the main process in the renal elimination of GAB. (AU)

FAPESP's process: 15/25728-2 - Influence of the organic cation transporter 2 (OCT2) inhibitor cimetidine and experimental diabetes mellitus on kinetic disposition of gabapentin in rats
Grantee:Jhohann Richard de Lima Benzi
Support type: Scholarships in Brazil - Master