Pharmacokinetics of morphine and its surrogates. VII: High-performance liquid chromatographic analyses and pharmacokinetics of methadone and its derived metabolites in dogs.

Reversed-phase HPLC assays with on-column UV detection and post-column fluorescent detection of ion pair-extracted material were developed and used for the quantitative assay of methadone, its presumed metabolites, and acid- and alkali-hydrolyzable conjugates of these metabolites in biological fluids with assay sensitivities of 10-20 ng/mL. Plasma, urine, and bile were monitored in dogs after intravenous bolus administration of 0.8, 1.

Influence of some humectants on the physical characteristics of solidified sodium stearate-based sticks.

Synopsis A comparative study was conducted on the influence of widely used humectants [glycerol, propylene glycol (PG), polyethylene glycols 400 and 600 (PEG 400 and PEG 600)] on the physical characteristics of solidified sodium stearate-based sticks (SSSS). - Sticks prepared with PG or PEG 600 generally tended to be harder than the corresponding ones containing glycerol or PEG 400; - PG lowered the penetrability of the sticks while PEG 400 tended to increase it. Glycerol or PEG 600 produced sticks with intermediate penetrability values; - all investigated sticks showed practically acceptable softening points; - PG-based sticks showed the lowest yield by abrasion values while PEG 400-based ones showed the highest such values.