Determination of theophylline in plasma: comparison of high-performance liquid chromatography and an enzyme multiplied immunoassay technique

Eppel, M. L.; Oliver, John S.; Smith, Hamilton; Mackay, A.D.; Ramsay, Lawrence E.

doi:10.1039/an9780301061

Cited by 8 publications

(2 citation statements)

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“…Thus, thsobromine may have been eluted together with the proteinaceous materials during the washing step. Despite this possible drawback, the method is preferred over solvent extraction procedures [8] which are more time consuming and frequently lead to emulsion formation and low recovery of caffeine and its metabolites.…”

Section: Discussionmentioning

confidence: 99%

Identification of 1,7‐dimethylxanthine as a metabolite of caffeine in the dog

Szeto

Tse

1981

J. High Resol. Chromatogr.

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Section: Discussionmentioning

confidence: 99%

Identification of 1,7‐dimethylxanthine as a metabolite of caffeine in the dog

Szeto

Tse

1981

J. High Resol. Chromatogr.

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“…(Eppel, Oliver, Smith, Mackay & Ramsay, 1978) and results by HPLC are reported. The many drugs used by patients in this study were not checked individually for interference in the assay, but the mean control plasma 'theophylline' concentration was 0.8 1.g/ml, and drug treatment was constant in all but one patient.…”

Section: Patientsmentioning

confidence: 99%

Oral sustained‐release aminophylline in medical inpatients: factors related to toxicity and plasma theophylline concentrations.

Ramsay¹,

Mackay²,

Eppel³

et al. 1980

Brit J Clinical Pharma

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1 Consecutive medical inpatients expected to benefit from a theophyllinate were treated with sustained-release aminophylline in a protocol conforming with ordinary practice. Of 16 patients, five had toxicity with aminophylline 450 mg daily, and a further three with 900 mg daily. Toxicity was serious in three patients. 2 Toxicity was significantly less common in cigarette smokers, and was related to higher plasma theophylline concentrations. However, there was a large overlap between concentrations associated with toxicity (as low as 9 pg/ml) and the accepted therapeutic range (5-20 pg/ml). Most patients with toxicity had theophylline levels within the therapeutic range. 3 For the same dose of aminophylline there was sevenfold variation between patients in plasma theophylline, with higher conentrations in non-smokers, infrequent alcohol users, older patients, those with left ventricular failure and those with lower serum transaminases. These variables could not be separated completely because of the small number of observations. 4 A nomogram for aminophylline dosage or monitoring of serum theophylline levels would have prevented little of the toxicity observed in these patients, although these measures would ensure that therapeutic concentrations were attained, and might prevent life-threatening toxicity.

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