The results of deoxyuridine suppression tests on the bone marrow cells of 14 patients on anticonvulsant drugs, 11 of whom had evidence of megaloblastic erythropoiesis, indicated that the megaloblastic changes and macrocytosis encountered in treated epileptics are often not caused either by folate deficiency or by drug-induced impairment of the 5, 10-methylenetetrahydrofolatedependent methylation of deoxyuridylate to thymidylate. A folate-related abnormality in the methylation of deoxyuridylate was found in only two of the 11 patients with megaloblastic erythropoiesis.
The syntheses of analogues of pemedolac (cis-1-ethyl-1,3,4,9-tetrahydro-4-(phenylmethyl)pyrano[3,4-b]indol e-1-acetic acid), a potent analgesic, are described. They were tested for analgesic and antiinflammatory effects in vivo and for inhibition of prostaglandin production in vitro. Analysis of structure-activity relationships shows that analgesic activity in this series is associated with 1S-cis stereochemistry, the presence of a pi-system (allyl or benzyl) at position 4, and a log P value greater than 4.0.
Suspensions of human bone marrow cells were incubated with various concentrationsof phenobarbitone or phenytoin sodium for 2 h, and the effects of this incubation on the subsequent incorporation of 3H-thymidine and 3H-leucine into DNA and protein, respectively, were studied. Both drugs caused a depression of 3H-thymidine incorporation and this phenomenon was not prevented by the addition of 100 ,ug of pteroylglutamic acid, folinic acid or 5-methyltetrahydrofolate per ml of marrow culture. The lowest concentration of drug which caused a statistically significant depression of 3H-thymidine incorporation was 200 pg per ml for phenobarbitone and 50 pg per ml for phenytoin sodium. Both phenobarbitone and phenytoin sodium also caused an increase in the incorporation of 3H-leucine at concentrations of 50 and 20 ,ug per ml, respectively, suggesting the possibility that a stimulation of protein synthesis within erythropoietic cells may play an important role in the development of anticonvulsantinduced macrocytosis.
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