title: Recovery of platelet function after withdrawal of cilostazol administered orally for a long period.
abstract: To clarify the recovery of platelet function after abrupt withdrawal of cilostazol, we studied platelet function and cilostazol concentration in elderly who received cilostazol, 100 mg twice a day (200 mg/day), for a long period. After interviewing the time of final cilostazol intake, platelet aggregability was determined with an aggregometer using four different concentrations of adenosine-5'-diphosphate as an inducer, which showed the grading curve (GC) type and platetet aggregatory threshold index (PATI). Serum cilostazol concentration was also determined by high-performance liquid chromatography. The GC type and PATI showed suppressed platelet function until 15 hours after withdrawal in half of patients. Bleeding time measured by the Simplate method was prolonged within 4 hours, but recovered by 12 hours after the withdrawal. Some serum cilostazol concentrations were still high 15 hours after withdrawal, while platelets were inhibited even in patients with low serum concentration of cilostazol. In the group receiving the drug for less than 6 months, PATI correlated with serum cilostazol concentration, but platelets in the long-term administration group (more than 48 months) were suppressed at the low serum cilostazol concentration. These findings indicated that platelet function recovered within 12-16 hours after withdrawal in these patients.
authors.affiliation: Department of Geriatric Medicine, Tokyo Medical University Hospital, Tokyo, Japan. i-wam@ma.kcom.ne.jp
authors.forename: Toshihiko
authors.initials: T
authors.lastname: Iwamoto
authors.forename: Kyoko
authors.initials: K
authors.lastname: Kin
authors.forename: Kaori
authors.initials: K
authors.lastname: Miyazaki
authors.forename: Kouichi
authors.initials: K
authors.lastname: Shin
authors.forename: Masaru
authors.initials: M
authors.lastname: Takasaki
mesh_terms: D000244:Adenosine Diphosphate / Q000494:pharmacology; D000284:Administration, Oral; D000368:Aged; D000369:Aged, 80 and over; D001792:Blood Platelets / Q000187:drug effects* / Q000502:physiology; D000077407:Cilostazol; D005260:Female; D006801:Humans; D066298:In Vitro Techniques; D008297:Male; D010974:Platelet Aggregation / Q000187:drug effects; D010975:Platelet Aggregation Inhibitors / Q000008:administration & dosage* / Q000097:blood; D013777:Tetrazoles / Q000008:administration & dosage* / Q000097:blood; D013997:Time Factors
chemical_list: D010975:Platelet Aggregation Inhibitors; D013777:Tetrazoles; D000244:Adenosine Diphosphate; D000077407:Cilostazol