Good correlation between clinical bleeding tendencies and bleeding pattern from the bleeding time incision

Study for determination of the optimal cessation period of therapy with anti-platelet agents prior to invasive endoscopic procedures

BACKGROUND

Anti-platelet agents are widely used for the treatment and prevention of thrombotic diseases. On the other hand, continuation of anti-platelet agents increases the risk of hemorrhagic complications in gastrointestinal endoscopy, and cessation of anti-platelet agents exposes the patient to the risk of thromboembolism. Only a few studies have actually studied the whether a cessation period is required prior to endoscopic procedures and if so, the optional duration of the period. The present study assessed the time course of primary hemostasis after the cessation of anti-platelet agents.

METHODS

Eleven healthy men (age range, 19-29 years) were assigned to each of the following regimens: aspirin (ASA; 100 mg/day), ticlopidine (TP; 300 mg/day), and a combination of ASA (100 mg/day) and TP (300 mg/day) for 7 days. There was a washout period of more than 3 weeks between each regimen. A quantitative bleeding time test (QBT test) and platelet aggregation test were performed before the beginning of administration, on the last day of administration, and at 1, 3, and 5 days after cessation, and also at 7 days after cessation for the combination regimen.

RESULTS

The average bleeding time (BT) and total bleeding loss volume (Tv) of the 11 subjects after administration of the three regimens were significantly increased compared with those before administration. With the administration of ASA, increases of BT and Tv at 3 days after cessation were not significant. The Tv at 5 days after cessation of TP was not significantly increased. With the combination regimen, the BT and Tv at 7 days after cessation were not significantly increased.

CONCLUSIONS

A 3-day cessation period for ASA, a 5-day cessation period for TP, and a 7-day cessation period for ASA+TP administration seem to be sufficient.

A randomized crossover comparative study of aspirin, cilostazol and clopidogrel in normal controls: analysis with quantitative bleeding time and platelet aggregation test

The effects of three antiplatelet drugs, aspirin, clopidogrel and cilostazol, were examined and compared using a quantitative bleeding time (QBT) test apparatus. In 12 healthy adult male subjects, a QBT test and platelet aggregation test were performed before and after medication. Cilostazol was found to be as effective as aspirin and clopidogrel in inhibiting platelet aggregation. Following the oral administration of aspirin and clopidogrel for 7 days, the bleeding time was significantly prolonged. In contrast, none of these QBT parameters were altered by the cilostazol treatment. This suggests that cilostazol has potent efficacy in inhibiting platelet aggregation without prolonging the bleeding time and changing the bleeding pattern.

Treatment with liposome-encapsulated clodronate as a new strategic approach in the management of immune thrombocytopenic purpura in a mouse model

Immune thrombocytopenic purpura (ITP) is an autoimmune disease related to the presence of elevated levels of platelet-associated immunoglobulin, or autoantibodies. In recent years the importance of macrophage Fcγ receptors in the uptake of platelets in ITP has been confirmed. Although in patients with ITP the platelet destruction occurs in liver and spleen, in this present experimental mouse model the liver was the principal organ of sequestration of sensitized platelets. The uptake in the spleen, bone marrow, lung, and kidneys was negligible and not different from that in control animals. In addition, the trapped platelets did not return to circulation, and new cells derived from the platelet-storage pool or new thrombocytogenesis were necessary to restore the platelet count. The depletion of splenic and hepatic murine macrophages by liposome-encapsulated clodronate (lip-clod) was studied as a new strategy for ITP treatment. Lip-clod inhibits, in a dose-dependent manner, the antibody-induced thrombocytopenia. Moreover, lip-clod treatment rapidly restored (24 hours) the platelet count in thrombocytopenic animals to hematologic safe values, and despite additional antiplatelet antiserum treatment, mice were able to maintain this level of platelets at least up to 48 hours. The bleeding times in lip-clod–treated animals was not different from those in controls, demonstrating that the hemostasis was well controlled in these animals. The results presented in this study demonstrate that lip-clod treatment can be effective in the management of experimental ITP.

Treatment with liposome-encapsulated clodronate as a new strategic approach in the management of immune thrombocytopenic purpura in a mouse model

Immune thrombocytopenic purpura (ITP) is an autoimmune disease related to the presence of elevated levels of platelet-associated immunoglobulin, or autoantibodies. In recent years the importance of macrophage Fcγ receptors in the uptake of platelets in ITP has been confirmed. Although in patients with ITP the platelet destruction occurs in liver and spleen, in this present experimental mouse model the liver was the principal organ of sequestration of sensitized platelets. The uptake in the spleen, bone marrow, lung, and kidneys was negligible and not different from that in control animals. In addition, the trapped platelets did not return to circulation, and new cells derived from the platelet-storage pool or new thrombocytogenesis were necessary to restore the platelet count. The depletion of splenic and hepatic murine macrophages by liposome-encapsulated clodronate (lip-clod) was studied as a new strategy for ITP treatment. Lip-clod inhibits, in a dose-dependent manner, the antibody-induced thrombocytopenia. Moreover, lip-clod treatment rapidly restored (24 hours) the platelet count in thrombocytopenic animals to hematologic safe values, and despite additional antiplatelet antiserum treatment, mice were able to maintain this level of platelets at least up to 48 hours. The bleeding times in lip-clod–treated animals was not different from those in controls, demonstrating that the hemostasis was well controlled in these animals. The results presented in this study demonstrate that lip-clod treatment can be effective in the management of experimental ITP.