Effect of doses on the bioavailability of phenytoin from a prompt-release and an extended-release preparation: single dose study.

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dc.contributor.authorRojanasthien, Noppamasen_US
dc.contributor.authorChaichana, Nuchanarten_US
dc.contributor.authorTeekachunhatean, Supanimiten_US
dc.contributor.authorKumsorn, Boonyiumen_US
dc.contributor.authorSangdee, Chaichanen_US
dc.contributor.authorChankrachang, Siwapornen_US
dc.date.accessioned2009-05-27T18:30:58Z
dc.date.available2009-05-27T18:30:58Z
dc.date.issued2007-09-26en_US
dc.descriptionChotmaihet Thangphaet.en_US
dc.description.abstractOBJECTIVE: To determine the effect of doses on the bioavailability of a prompt-release and an extended-release phenytoin capsule after given as single doses. MATERIAL AND METHOD: Eight healthy male volunteers were given single oral doses of 100, 200, and 300 mg of a prompt-release preparation (Ditoin) and an extended-release phenytoin (Dilantin Kapseals) preparation in a crossover design with a two weeks washout period after an overnight fast. Serial blood samples were collected over 72 h post-dose. Plasma phenytoin concentrations were determined by HPLC and pharmacokinetic parameters were analyzed by non-compartmental model. RESULTS: Rate of phenytoin absorption from the prompt-release preparation was more prolonged after the 300mg dose (T(max) 4.5 h) than those of the 100- and 200-mg doses (T(max) 3.5 and 3 h, respectively). Similarly, the T(max) of the 200- and the 300-mg extended-release preparation (5.5 and 4 h) were more prolonged than the 100-mg dose (3 h). Bioequivalence analysis showed that the C(max) of all doses of the prompt-release preparation were higher than those values of the extended-release preparation with the mean C(max) ratio (90% CI) of 1.32 (1.24-1.40), 1.26 (1.14-1.40), and 1.29 (1.10-1.51) for the 100-, 200- and 300-mg doses, respectively. The extent of absorption (AUC(0-infinity)) of 100-mg phenytoin was bioequivalent between the two preparations [mean AUC ratio (90% CI) of 1.15 (1.11-1.18)], however, for higher doses, the prompt-release products produced higher bioavailability than the extended-release products [mean AUC ratio (90% CI) of 1.19 (1.07-1.33) and 1.17 (0.98-1.38), respectively for the 200- and 300-mg doses]. The difference in the bioavailability did not affect the elimination of phenytoin and their half-lives were comparable (11-13 h). CONCLUSION: The bioavailability of phenytoin from both preparations increased proportionally over the dose range of 100-300-mg, however, the bioavailability of the prompt-release preparation was higher than the corresponding doses of the extended-release product.en_US
dc.description.affiliationDepartment of Pharmacology, Faculty of Medicine, Chiang Mai University, Chiang Mai 50200, Thailand. nrojanas@mail.med.cmu.ac.then_US
dc.identifier.citationRojanasthien N, Chaichana N, Teekachunhatean S, Kumsorn B, Sangdee C, Chankrachang S. Effect of doses on the bioavailability of phenytoin from a prompt-release and an extended-release preparation: single dose study. Journal of the Medical Association of Thailand. 2007 Sep; 90(9): 1883-93en_US
dc.identifier.urihttps://imsear.searo.who.int/handle/123456789/39302
dc.language.isoengen_US
dc.source.urihttps://www.mat.or.th/journal/all.phpen_US
dc.subject.meshAdulten_US
dc.subject.meshArea Under Curveen_US
dc.subject.meshBiological Availabilityen_US
dc.subject.meshChromatography, High Pressure Liquiden_US
dc.subject.meshCross-Over Studiesen_US
dc.subject.meshDelayed-Action Preparationsen_US
dc.subject.meshDrug Monitoringen_US
dc.subject.meshHumansen_US
dc.subject.meshMaleen_US
dc.subject.meshPhenytoin --administration & dosageen_US
dc.subject.meshTime Factorsen_US
dc.titleEffect of doses on the bioavailability of phenytoin from a prompt-release and an extended-release preparation: single dose study.en_US
dc.typeClinical Trialen_US
dc.typeJournal Articleen_US
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