Abstract
Respiratory depression and death secondary to respiratory arrest have occurred after oral overdoses of γ-hydroxybutyrate (GHB) and its precursor γ-butyrolactone (GBL). GHB is a substrate for monocarboxylate transporters (MCTs), and increasing GHB renal clearance or decreasing GHB absorption via MCT inhibition represents a potential treatment strategy for GHB/GBL overdose. In these studies, GHB and GBL were administered in doses of 1.92, 5.77, and 14.4 mmol/kg orally with and without MCT inhibition to determine effects of this treatment strategy on the oral toxicokinetics and toxicodynamics of GHB and GBL. The competitive MCT inhibitor l-lactate was administered by intravenous infusion starting 1 hour after GHB and GBL administration. Oral administration of l-lactate and the MCT inhibitor luteolin was also evaluated. Respiratory depression was measured using plethysmography. Intravenous l-lactate, but not oral treatments, significantly increased GHB renal and/or oral clearances. At the low dose of GHB and GBL, i.v. l-lactate increased GHB renal clearance. Due to the increased contribution of renal clearance to total clearance at the moderate dose, increased renal clearance translated to an increase in oral clearance. At the highest GHB dose, oral clearance was increased without a significant change in renal clearance. The lack of effect of i.v. l-lactate on renal clearance after a high oral GHB dose suggests possible effects of i.v. l-lactate on MCT-mediated absorption. The resulting increases in oral clearance improved respiratory depression. Intravenous l-lactate also reduced mortality with the high GBL dose. These data indicate i.v. l-lactate represents a potential treatment strategy in oral overdose of GHB and GBL.
Footnotes
- Received December 19, 2012.
- Accepted February 6, 2013.
This work was supported by the National Institutes of Health National Institute on Drug Abuse [Grant DA023223]; and by a fellowship from Pfizer Global Research and Development.
A portion of this work was previously presented as an abstract at the following meeting: Morse BL and Morris ME (2012) Effect of monocarboxylate transporter inhibition on the oral toxicokinetics/toxicodynamics of γ-hydroxybutyrate (GHB) and γ-butyrolactone (GBL). 2012 Annual Meeting & Exposition of the American Association of Pharmaceutical Sciences; 2012 Oct 14–18; Chicago, IL.
- Copyright © 2013 by The American Society for Pharmacology and Experimental Therapeutics
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