Harvey J. Kupferberg

Quantitative estimation of diphenylhydantoin, primidone and phenobarbital in plasma by gas-liquid chromatography.

Abstract A gas-liquid Chromatographic method for the simultaneous determination of phenobarbital, primidone and diphenylhydantoin in human plasma following therapeutic doses has been developed. After extraction, the anticonvulsants are methylated directly in the flash-heater of the gas chromatograph with trimethylanilinium hydroxide. Linear temperature programming is used to achieve separation and quantitation. The method has the advantages of specificity, sensitivity and simple derivative formation.

A radioimmunoassay for diphenylhydantoin

Abstract A radioimmunoassay for the anticonvulsant compound diphenylhydantoin (DPH) has been developed. Antisera were prepared by immunizing animals with a DPH-chicken γ-globulin conjugate. The assay depends on the capacity of unlabelled DPH to compete with a known amount of [14C]DPH for the antibody-binding sites. The assay can detect as little as 0.03 μg of DPH in 0.1 ml sample. Studies of the specificity of the reaction revealed that the antisera reacted as effectively with 5-(P-hydroxyphenyl)-5-phenylhydantoin as with DPH and that they reacted very poorly or not at all with mephenytoin and ethotoin, other hydantoin derivatives. The presence of large amounts of phenobarbital did not interfere with the binding of [14C]-DPH to antibody. Parallel analysis by radioimmunoassay and by gas-liquid chromatography of DPH plasma levels in 10 patients receiving the drug for seizure control revealed an excellent correlation between the two methods. This simple, sensitive, and rapid assay offers several distinct advantages over other currently available methods for assaying plasma DPH levels.

Effect of methylphenidate on plasma anticonvulsant levels

The effect of the oral administration of 30 mg. of methylphenidate daily on serum levels of phenobarbital, diphenylhydantoin, and primidone was evaluated in 11 patients. One group of patients was assigned to an 18 week treatment period of 6 weeks each for control, methylphenidate, and control; another group was studied in similar fashion for methylphenidate, control, and methylphenidate. Plasma anticonvulsant levels were determined at weekly intervals. No significant differences in plasma anticonvulsant levels were noted during methylphenidate administration.

Dose-response evaluations of a circadian rhythmic change in susceptibility of mice to ouabain

Abstract Relations between dose of ouabain, administered to mice either intraperitoneally or subcutaneously, and mortality were examined at times of high and low response in the previously reported circadian rhythm in susceptibility to this drug, i.e., at about 08:00 and 20:00 for mice housed under standard conditions, including light from 06:00 to 18:00 and darkness from 18:00 and 06:00. Animals tested at about 08:00 on the regimen showed significantly higher susceptibility to ouabain, regardless of the route of administration. Parallelism of dose-response relations for the two times of administration suggests a similarity in the mechanism of drug action. Possible changes underlying the circadian rhythm in susceptibility of mice to ouabain are briefly discussed.

Heat production and heat loss in d-amphetamine hyperthermia in aggregated swiss webster and bdf1 mice.

Heat Production and Heat Loss in d-Amphetamine Hyperthermia in Aggregated Swiss Webster and BDF1 Mice. The difference in response of aggregated Swiss Webster and BDF1 mice to the hyperthermic effects of d-amphetamine was investigated. Heat production via motor activity and plasma free fatty acid stimulation were studied. The concentration of plasma free fatty acids in aggregated amphetaminetreated Swiss Webster and BDF1 mice did not follow any consistent relationship with either the dose of amphetamine or the hyperthermia produced by it. Motor activity measurements also failed to show any differences that would account for the differential hyperthermia caused by amphetamine. Differences in heat production via free fatty acids and motor activity did not explain the differences in hyperthermia. Heat production was also estimated by oxygen utilization in aggregated Swiss Webster and BDF1 mice. The indirect calorimetric oxygen utilization studies failed to show any strain difference which would account for the differences in hyperthermia. Heat loss by evaporative water loss was also measured after amphetamine administration. At room temperatures of 19° and 27°C, the BDF1 mice were found to lose more heat through evaporation than the Swiss Webster mice after 20 mg/kg d-amphetamine sulfate. Thus, the pharmacogenetic difference in toxic and hyperthermic responses of aggregated Swiss Webster and BDF1 mice was explained by a difference in evaporative water loss (heat loss) between the two strains.