A Simple Technique for the Rapid Estimation of Ethosuximide by Gas Liquid Chromatography

Latham, A. N.; Macpherson, G.S.

doi:10.1111/j.1365-2125.1974.tb00210.x

Cited by 8 publications

(4 citation statements)

References 11 publications

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“…Measurements of total and free PHT and total CBZ were made by enzyme immunoassay (EMIT) (Anonymous, 1982), and VPA and PB were measured by polarization fluoroimmunoassay (Lu-Steffes et al, 1982;Anonymous, 1984). Total and free carbamazepine-l0,ll-epoxide (CBZ-E) and free CBZ concentrations were measured by highperformance liquid chromatography (HPLC) (Elyas et al, 1982), and ESM was measured by gas chromatography (Latham and Macpherson, 1974).…”

Section: Methodsmentioning

confidence: 99%

Effects of Discontinuation of Phenytoin, Carbamazepine, and Valproate on Concomitant Antiepileptic Medication

Duncan¹,

Patsalos²,

Shorvon³

1991

Epilepsia

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We report a prospective, controlled study of the effects of the reduction and discontinuation of phenytoin (PHT) (22 patients), carbamazepine (CBZ) (23 patients), and valproate (VPA) (25 patients) with concomitant antiepileptic drugs (AEDs). The principal changes in the serum concentrations of concomitant AEDs were (a) phenobarbital (PB) concentrations decreased by a mean of 30% on discontinuation of PHT; (b) total CBZ concentrations increased by a mean of 48% and free CBZ concentrations increased by a mean of 30% on discontinuation of PHT, with no change in CBZ-10, 11-epoxide (CBZ-E) concentrations; (c) VPA concentrations increased by a mean of 19% on discontinuation of PHT; (d) VPA concentrations increased by a mean of 42% on discontinuation of CBZ; (e) ethosuximide (ESM) concentrations increased by a mean of 48% on discontinuation of CBZ; (f) PHT concentrations decreased by a mean of 26% on discontinuation of CBZ; (g) PHT free fraction decreased from a mean of 0.11 to 0.07 on discontinuation of VPA; and (h) the mean concentrations of total and free CBZ increased by a mean of 10 and 16%, respectively, on VPA discontinuation, with a concomitant mean 24% decrease in total CBZ-E and a 22% decrease in free CBZ-E. Apart from the decrease in PB concentrations on PHT discontinuation, all significant changes had occurred by 1 week after the end of AED discontinuation. The implication for clinical practice is that a serum AED concentration at this time reflects the new steady state. Free concentrations did not add any clinically useful information to that gained from analysis of total serum concentrations.

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Section: Methodsmentioning

confidence: 99%

Effects of Discontinuation of Phenytoin, Carbamazepine, and Valproate on Concomitant Antiepileptic Medication

Duncan¹,

Patsalos²,

Shorvon³

1991

Epilepsia

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“…Trough serum AED concentrations were assessed on the same days as AP testing was carried out. PHT and CBZ concentrations were measured by homogenous enzyme immunoassay (Emit, Syva UK), VPA and PB by fluorescence polarization immunoassay (TDX, Abbott) and ethosuximide (ESM) by gas liquid chromatography (Latham & McPherson, 1974).…”

Section: Methodsmentioning

confidence: 99%

“…PHT and CBZ concentrations were measured by homogenous enzyme immunoassay (Emit, Syva UK), VPA and PB by fluorescence polarization immunoassay (TDX, Abbott) and ethosuximide (ESM) by gas liquid chromatography (Latham & McPherson, 1974 PHT removal (comedic babiturate) (n = 9); ----PHT removal ( CBZ) (n = 11); CBZ removal (co] PHT +/-barbiturate) (n = 10); ----CB inducing comedication) (n = 5); V (all with inducing comedication) (n = 1 enzyme inducing drug (three reduci therapy with VPA, and two to VP The remaining 10 patients took PI and/or barbiturates (4 cases) (Ta patients who discontinued VPA i inducing AEDs (Table 3).…”

Section: Introductionmentioning

confidence: 99%

Effect of the removal of individual antiepileptic drugs on antipyrine kinetics, in patients taking polytherapy.

Patsalos

Duncan

Shorvon

1988

Brit J Clinical Pharma

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1 Antipyrine (AP) clearance, half-life and volume of distribution were determined in 52 patients, taking one or more antiepileptic drug (AED), before and 4 weeks after the complete removal of phenytoin (PHT, n = 20), carbamazepine (CBZ, n = 15) and sodium valproate (VPA, n = 17). 2 PHT removal was associated with a mean 13% fall in AP clearance and a mean 16% increase in AP half-life, in patients who were also taking CBZ with or without barbiturates. There was no significant difference between patients who did, and did not, take barbiturates, in addition to CBZ. 3 CBZ removal was associated with a mean 45% fall in AP clearance and a mean 69% increase in AP half-life, if there was no inducing AED comedication, but had no effect on AP clearance and half-life if PHT and/or barbiturates were also being taken. 4 Removal of VPA had no effect on AP clearance or half-life. 5 The removal of PHT, CBZ and VPA had no significant effect on AP volume of distribution. 6 PHT appears to be a more powerful inducer of hepatic enzyme activity, as measured by the AP test, than is CBZ.

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“…After extraction, drugs have been chromatographed either with (Kupferberg, 1970;Baylis, Fry & Marks, 1970;Miyumoto, Seino, Ikeda & Yamagami, 1973) or without (Pippenger & Gillen, 1969;Toseland, Grove & Berry, 1972;Papadopoulos et al, 1970) the prior formation of less polar derivatives. This paper describes an extension of the method of Latham & MacPherson (1974) for the quantitation of ethosuximide to incorporate, in addition, a reliable quantitative assay for phenobarbitone, primidone and diphenylhydantoin from 1 ml of human serum.…”

Section: Introductionmentioning

confidence: 99%

Simultaneous quantitative gas‐chromatographic analysis of ethosuximide, phenobarbitone, primidone and diphenylhydantoin.

Latham¹,

Varlow²

1976

Brit J Clinical Pharma

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1 Therapeutic serum concentrations of ethosuximide, phenobarbitone, primidone, and dipheylhydantoin were assayed from 1 ml of human serum. The extraction procedure was common to all four drugs and three internal standards. 2 Subsequent isothermal gas chromatographic analysis of serum extracts produced well resolved peaks for the underivatized quantitation of ethosuximide and phenobarbitone. Primidone and diphenylhydantoin were determined as methylated derivatives. 3 Mean coefficients of variation for the assay of each drug were less 7% on a newly packed and conditioned column and less than 10% after the technique had been in continuous use for 3 months. 4 The advantage of quantitation relative to peak area ratios rather than peak height ratios was minimal for the determination of ethosuximide, primidone and diphenylhydantoin but appeared significant for the assay of phenobarbitone.

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A Simple Technique for the Rapid Estimation of Ethosuximide by Gas Liquid Chromatography

Cited by 8 publications

References 11 publications

Effects of Discontinuation of Phenytoin, Carbamazepine, and Valproate on Concomitant Antiepileptic Medication

Effects of Discontinuation of Phenytoin, Carbamazepine, and Valproate on Concomitant Antiepileptic Medication

Effect of the removal of individual antiepileptic drugs on antipyrine kinetics, in patients taking polytherapy.

Simultaneous quantitative gas‐chromatographic analysis of ethosuximide, phenobarbitone, primidone and diphenylhydantoin.

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