Serum concentrations of gabapentin in cats with chronic kidney disease.

Objectives: The purpose of this study was to assess serum concentrations of gabapentin in cats with chronic kidney disease (CKD) vs clinically healthy cats.

Methods: Five healthy cats were enrolled in a pharmacokinetic study. A single 20 mg/kg dose of gabapentin was administered orally and blood was obtained at 0, 0.25, 0.5, 1, 1.5, 2, 3, 4, 8, 12, 24 and 36 h via a jugular catheter. Serum gabapentin concentrations were measured using liquid chromatography coupled to tandem mass spectrometry. Non-compartmental pharmacokinetic analysis was performed. The same five healthy cats plus 25 cats with stable International Renal Interest Society stage 2 (n = 14) and 3 (n = 11) CKD were enrolled in a limited sampling study. Cats in both groups received a single 10 mg/kg dose of gabapentin, and serum gabapentin concentrations and compliance scores were obtained 3 and 8 h post-administration.

Results: Cats with CKD had significantly higher dose-normalized serum gabapentin concentrations than normal cats at 3 h ( = 0.0012 CKD vs normal 10 mg/kg;  = 0.008 CKD vs normal 20 mg/kg) and 8 h ( <0.0001 CKD vs normal 10 mg/kg; <0.0001 CKD vs normal 20 mg/kg). Both 3 and 8 h dose-normalized serum gabapentin concentrations were significantly correlated with serum creatinine (3 h:  = 0.03,  = 0.39; 8 h:  = 0.001,  = 0.57) and symmetric dimethylarginine (3 h:  = 0.03,  = 0.41; 8 h:  = 0.007,  = 0.48). There was a significant correlation between 3 h serum gabapentin concentrations and compliance scores ( = 0.0002,  = 0.68).

Conclusions And Relevance: Cats with CKD that received 10 mg/kg of gabapentin had significantly higher dose-normalized serum concentrations than normal cats that received 20 mg/kg, supporting the need to dose-reduce in this patient population.