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PubMed · 12154319

Polymorphic forms of cilostazol.

Linda B Whittall·Robert R Whittle·Grayson W Stowell
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Abstract

Two unique conformational polymorphic forms of the compound 6-[4-(1-cyclohexyl-1H-tetrazol-5-yl)butoxy]-3,4-dihydroquinolin-2(1H)-one (cilostazol), C(20)H(27)N(5)O(2), have been discovered and characterized using single-crystal X-ray structural analysis. A third polymorph also exists, but acceptable crystals could not be obtained. Features of both reported polymorphic structures include a chair conformation of the cyclohexyl ring and puckering in the quinolinone ring. The major feature distinguishing the two polymorphic forms is a rotational twisting of the butoxy chain between the tetrazole and quinolinone rings. This difference in conformation influences the intermolecular forces, and hence the packing of the two molecules during crystallization.

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CilostazolCrystallography, X-RayHydrogen BondingModels, MolecularPlatelet Aggregation InhibitorsTetrazolesJournal Article

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Linda B Whittall, Robert R Whittle, Grayson W Stowell. 2002-07-31. Polymorphic forms of cilostazol.. https://doi.org/10.1107/s0108270102012544

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PubMed2006

Pharmacodynamic interaction studies of Ginkgo biloba with cilostazol and clopidogrel in healthy human subjects.

AIMS: Ginkgo biloba is available as an over-the-counter drug and reported to cause haemorrhage when coadministered with other antiplatelet agents. We set out to study the interactions of G. biloba with cilostazol and clopidogrel. METHODS: A randomized, open-label, crossover study of 10 healthy male volunteers. The dosage schedules were 120 mg G. biloba, 240 mg G. biloba, 100 mg cilostazol, 200 mg cilostazol, 75 mg clopidogrel, 150 mg clopidogrel, 120 mg G. biloba+ 100 mg cilostazol and 120 mg G. biloba+ 75 mg clopidogrel. Platelet aggregation, platelet count, bleeding time and clotting time were measured 0 and 6 h after drug administration. Platelet aggregation was performed using a dual channel aggregometer, by the turbimetric technique using adenosine diphosphate 5 micromol and 10 micromol, and collagen 1 microg ml(-1). RESULTS: Platelet inhibition with the combination of G. biloba and clopidogrel or cilostazol was not statistically significant compared with individual doses of drugs, with all the three aggregants. There was significant (P < 0.05) potentiation of prolongation of bleeding time with the combination of cilostazol and G. biloba compared with individual doses of both the drugs. There was no significant change in clotting time and platelet count. CONCLUSIONS: Coadministration of G. biloba either with cilostazol or clopidogrel did not enhance antiplatelet activity compared with individual agents. Ginkgo biloba potentiated the bleeding time prolongation effect of cilostazol. There was no significant correlation between prolongation of bleeding time and inhibition of platelet aggregation.

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