PHENYTOIN DOSE ADJUSTMENT IN EPILEPTIC PATIENTS
| Autor: | G.E. Mawer, Margaret Rodgers, A.J. Robins, P. W. Mullen, S.B. Lucas |
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| Rok vydání: | 1974 |
| Předmět: |
Pharmacology
Phenytoin medicine.medical_specialty Test dose business.industry digestive oral and skin physiology Serum concentration medicine.disease nervous system diseases Phenytoin Sodium stomatognathic diseases Epilepsy Therapeutic index Endocrinology Internal medicine Papers otorhinolaryngologic diseases medicine Pharmacology (medical) Steady state (chemistry) Phenytoin Dose business medicine.drug |
| Zdroj: | British Journal of Clinical Pharmacology. 1:163-168 |
| ISSN: | 0306-5251 |
| DOI: | 10.1111/j.1365-2125.1974.tb00226.x |
| Popis: | 1 A preliminary survey showed that many outpatients with partially controlled epilepsy had serum concentrations of phenytoin below the recommended therapeutic range (10-20 μg/ml). A phenytoin tolerance test was devised with the intention of predicting a more adequate daily dose for such a patient. 2 Fifteen patients were each given an oral test dose of 600 mg phenytoin sodium and the serum concentration of phenytoin was measured at intervals over 48 h; the concentration rose during the first 4 h and decayed between 12-48 h as an almost linear function of time. 3 The serum concentration/time curves were fitted by an interative computer program based on the Michaelis-Menten equation. The mean saturated rate of elimination of phenytoin was 435 mg/day and the serum concentration (K(m)) corresponding with 50% saturation was 3.8 μg/ml. The mean calculated dose of phenytoin sodium required for a steady state serum concentration of 10-20 μg/ml was 345-400 mg/day. 4 The Michaelis-Menten principle was used to predict steady state serum phenytoin concentrations in individual patients receiving daily doses of phenytoin sodium adjusted by steps of 100 mg. The serum concentrations tended to be either too low or too high. The steep relationship between phenytoin concentration and dose indicates that when the concentration reaches 5-10 μg/ml it is then appropriate to adjust dose by small steps of about 25 mg. |
| Databáze: | OpenAIRE |
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