Effect of therapeutic plasma exchange on phenytoin plasma concentration in patients receiving intravenous fosphenytoin therapy.

S Nishida, Y Hayashi, K Hirai, A Takekoshi, Y Yamada, R Kobayashi, S Shimizu, T Niwa, H Hayashi, T Shimohata, T Sugiyama, A Suzuki

Die Pharmazie 2020 Oct 01

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We report for patients with encephalitis treated with plasma exchange (PE) and fosphenytoin. In patient 1, phenytoin levels decreased on the maintenance dose, and the phenytoin concentration was <10 μg/mL on day 12 of administration. In patient 2, the phenytoin levels was <10 μg/mL on day 4. Increasing the fosphenytoin dose pushed the phenytoin level into therapeutic range. There were no differences between the areas under the concentration-time curve of phenytoin with and without PE. We previously reported a decline in phenytoin levels after prolonged use of fosphenytoin. Therefore, dose adjustment of fosphenytoin in patients undergoing PE may be unnecessary.

Citation

S Nishida, Y Hayashi, K Hirai, A Takekoshi, Y Yamada, R Kobayashi, S Shimizu, T Niwa, H Hayashi, T Shimohata, T Sugiyama, A Suzuki. Effect of therapeutic plasma exchange on phenytoin plasma concentration in patients receiving intravenous fosphenytoin therapy. Die Pharmazie. 2020 Oct 01;75(10):488-490