Monocarboxylate Transporter Inhibition with Osmotic Diuresis Increases γ-Hydroxybutyrate Renal Elimination in Humans: A Proof-of-Concept Study.
OBJECTIVE
The purpose of the current study was to demonstrate proof-of-concept that monocarboxylate transporter (MCT) inhibition with L-lactate combined with osmotic diuresis increases renal clearance of γ-hydroxybutyrate (GHB) in human subjects. GHB is a substrate for human and rodent MCTs, which are responsible for GHB renal reabsorption, and this therapy increases GHB renal clearance in rats.


METHODS
Ten healthy volunteers were administered GHB orally as sodium oxybate 50 mg/kg (4.5 gm maximum dose) on two different study days. On study day 1, GHB was administered alone. On study day 2, treatment of L-lactate 0.125 mmol/kg and mannitol 200 mg/kg followed by L-lactate 0.75 mmol/kg/hr was administered intravenously 30 minutes after GHB ingestion. Blood and urine were collected for 6 hours, analyzed for GHB, and pharmacokinetic and statistical analyses performed.


RESULTS
L-lactate/mannitol administration significantly increased GHB renal clearance compared to GHB alone, 439 vs. 615 mL/hr (P=0.001), and increased the percentage of GHB dose excreted in the urine, 2.2 vs. 3.3% (P=0.021). Total clearance was unchanged.


CONCLUSIONS
MCT inhibition with L-lactate combined with osmotic diuresis increases GHB renal elimination in humans. No effect on total clearance was observed in this study due to the negligible contribution of renal clearance to total clearance at this low GHB dose. Considering the nonlinear renal elimination of GHB, further research in overdose cases is warranted to assess the efficacy of this treatment strategy for increasing renal and total clearance at high GHB doses.
Department of Pharmaceutical Sciences, School of Pharmacy and Pharmaceutical Sciences, University at Buffalo, State University of New York, Buffalo, NY (Morris and Morse).
Marilyn E
ME
Morris
Department of Pharmaceutical Sciences, School of Pharmacy and Pharmaceutical Sciences, University at Buffalo, State University of New York, Buffalo, NY (Morris and Morse).
Bridget L
BL
Morse
Department of Psychiatry, University of Rochester Medical Center, University of Rochester, Rochester, NY (Baciewicz and Tessena).
Gloria J
GJ
Baciewicz
Department of Psychiatry, University of Rochester Medical Center, University of Rochester, Rochester, NY (Baciewicz and Tessena).
Matthew M
MM
Tessena
Departments of Pharmacy and Emergency Medicine, University of Rochester Medical Center, University of Rochester, Rochester, NY (Acquisto).
Nicole M
NM
Acquisto
Department of Pharmacy Practice, School of Pharmacy, St. John Fisher College, Rochester, NY (Hutchinson).
David J
DJ
Hutchinson
Department of Pharmacy Practice, Albany College of Pharmacy and Health Sciences, Albany, NY (DiCenzo).
Robert
R
Dicenzo
Monocarboxylate transporter; Pharmacokinetics; Renal clearance; γ-hydroxybutyrate