Methadone maintenance: effect of urinary pH on renal clearance in chronic high and low doses.
The subjects were 12 male patients stabilized on methadone for many months or years. A comparison was made of the plasma levels and renal clearance of methadone between patients on "high" doses (80 to 110 mg/day) and those on "low" doses (15 to 40 mg/day). A general trend to higher renal clearance was seen in the "high" -dose group, but on more detailed examination there was a direct correlation only when the patients were categorized by urinary pH. At low pHs, there was nearly a 3-fold increase in renal clearance which was associated with a decreased major metabolite to methadone ratio. No evidence for a difference in rate of metabolism between the two groups was found nor were there differences in hepatic function. It was concluded that urinary pH was a major factor in renal clearance of methadone.
D000328:Adult; D001711:Biotransformation; D002849:Chromatography, Gas; D004334:Drug Administration Schedule; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007668:Kidney / Q000378:metabolism*; D007700:Kinetics; D008111:Liver Function Tests; D008297:Male; D013058:Mass Spectrometry; D008657:Metabolic Clearance Rate; D008691:Methadone / Q000008:administration & dosage / Q000378:metabolism* / Q000627:therapeutic use; D008875:Middle Aged; D019966:Substance-Related Disorders / Q000378:metabolism / Q000534:rehabilitation; D013997:Time Factors
D008691:Methadone