title: The pharmacokinetics of methanol in the presence of ethanol: a case study.
abstract: OBJECTIVE
  Methanol is a toxic alcohol that can cause significant morbidity and mortality in overdose, while ethanol is a readily available and effective antidote. Little is known about the pharmacokinetics of methanol in the presence of ethanol and vice versa. This paper explores the influence of methanol and ethanol on the pharmacokinetics of each other along with the effect of continuous venovenous haemodiafiltration (CVVHD) on alcohol removal.
  
  
  METHODS
  Multiple plasma, urine and dialysate samples were collected from a 42-year-old male who ingested 166 g of methanol. Methanol and ethanol concentrations in both plasma and urine were assayed and the concentration-time data were modelled using nonlinear mixed-effects modelling software NONMEM® VI. Simulations were performed using the final model parameters in MATLAB® software where a variety of initial doses and ethanol infusions were assessed.
  
  
  RESULTS
  The final model included a competitive metabolic interaction between methanol and ethanol as well as first-order elimination due to renal, CVVHD and an additional non-renal non-CVVHD mechanism. Simulations from the model show a loading dose of 28.4 g/70 kg of ethanol results in a target plasma concentration of 1 g/L. Due to the competitive interaction between methanol and ethanol, higher amounts of methanol require lower maintenance doses of ethanol but for longer. CVVHD was shown to increase the dose rate of ethanol required but to decrease the duration of the maintenance phase.
  
  
  CONCLUSIONS
  A detailed understanding of the pharmacokinetics of methanol and ethanol in the presence of each other is required to accurately determine the doses of ethanol required to treat different methanol poisonings.
authors.affiliation: School of Pharmacy, University of Otago, Dunedin, New Zealand. carolyn.coulter@otago.ac.nz
authors.forename: Carolyn V
authors.initials: CV
authors.lastname: Coulter
authors.forename: Geoffrey K
authors.initials: GK
authors.lastname: Isbister
authors.forename: Stephen B
authors.initials: SB
authors.lastname: Duffull
mesh_terms: D000328:Adult; D000437:Alcoholism / Q000097:blood / Q000378:metabolism* / Q000652:urine; D000931:Antidotes / Q000008:administration & dosage / Q000032:analysis / Q000493:pharmacokinetics* / Q000627:therapeutic use; D003198:Computer Simulation; D015314:Dialysis Solutions / Q000737:chemistry; D004334:Drug Administration Schedule; D004347:Drug Interactions; D016903:Drug Monitoring; D000431:Ethanol / Q000008:administration & dosage / Q000032:analysis / Q000493:pharmacokinetics* / Q000627:therapeutic use; D017583:Hemodiafiltration; D006801:Humans; D008297:Male; D008657:Metabolic Clearance Rate; D000432:Methanol / Q000097:blood / Q000493:pharmacokinetics* / Q000506:poisoning / Q000652:urine; D008954:Models, Biological; D012997:Solvents / Q000032:analysis / Q000493:pharmacokinetics* / Q000506:poisoning
chemical_list: D000931:Antidotes; D015314:Dialysis Solutions; D012997:Solvents; D000431:Ethanol; D000432:Methanol