Aspirin sensitivity of platelet aggregation in diabetes mellitus.

Although aspirin is cardioprotective in high-risk populations, many with diabetes mellitus (DM) are unresponsive to these benefits. We questioned whether cardiovascular unresponsiveness might be demonstrated by lack of aspirin sensitivity to in vitro platelet functions especially in subjects with poorly controlled diabetes. Six women and 4 men (48+/-8 years [mean+/-S.D.]), selected for poor control (glycohemoglobin 11.9+/-2.2%) and 10 sex-age (+/-5 years) matched controls received 81 mg aspirin daily. There was a 2-week washout from aspirin and related drugs. After the aspirin dose on day-7, blood for platelet aggregation assays, and 24-h urine for 2,3 dinor thromboxane B2 (TxB2) and 2,3 dinor 6-keto (PGF1alpha) were obtained. Aspirin sensitivity was defined as inhibition (i.e., lower than expected) platelet aggregation after exposure to an agonist. Those with diabetes and controls were sensitive to aspirin inhibition of platelet aggregation induced by 1.6 mM arachidonic acid (9.5+/-3.9% versus 9.1+/-3.1%, normal range 40-100%) and by 0.83 microg/mL collagen (17.4+/-13.9% versus 13.2+/-9.3%, normal range 60-93%), respectively. Aspirin sensitivity to 2 microM ADP was present in five with diabetes and five controls. Urinary prostaglandin metabolites were suppressed below reference ranges, without differences between those with DM or controls for TxB2 (350+/-149 pg/mg versus 348+/-93 pg/mg creatinine) and PGF1alpha (255+/-104 pg/mg versus 222+/-88 pg/mg creatinine). In conclusion, in poorly controlled diabetes, there was no differential lack of aspirin sensitivity to platelet aggregation, or lack of aspirin suppression of urinary TxB2 or PGF1alpha, compared with controls on aspirin. Despite suppression of urinary prostaglandin metabolites, aspirin resistance was most apparent to ADP-mediated platelet aggregation. It is not known what level of inhibition of in vitro tests is necessary for the cardioprotective benefits of aspirin in diabetes mellitus. Thus, the lack of aspirin protection in diabetes may be due to undefined aspects of platelet function.

Pharmacokinetic analysis of plasma-derived and recombinant F IX concentrates in previously treated patients with moderate or severe hemophilia B.

BACKGROUND: Hemophilia B is an X-linked bleeding disorder that affects approximately 1 in 25,000 males. Therapy for acute bleeding episodes consists of transfusions of plasma-derived (pd-F IX) or recombinant (r-F IX) concentrates. STUDY DESIGN AND METHODS: A double-blind, two-period crossover study was initiated to assess the pharmacokinetics of pd-F IX and r-F IX and to address patient-specific variables that might influence in vivo recovery. Study product was administered by a single bolus infusion (50 IU/kg) to 43 previously treated patients in the nonbleeding state, and F IX:C levels were measured over a period of 48 hours after infusion. RESULTS: The mean in vivo recovery in the pd-F IX group was 1.71 +/- 0.73 IU per dL per IU per kg compared with 0.86 +/- 0.31 IU per dL per IU per kg with r-F IX (p

Recombinant factor VIIa: a universal hemostatic agent?

Recombinant factor VIIa (rVIIa) has proved effective for the treatment and prevention of hemorrhage in patients with inherited hemophilia A and B who develop inhibitors to factor VIII or IX, and patients with acquired hemophilia A. More recently, there is evidence that rVIIa may also be effective in the control of abnormal bleeding in a variety of other conditions, such as inherited factor VII deficiency, thrombocytopenia, Glanzmann's thrombasthenia, and liver disease. In some of the reports, rVIIa appeared to be effective in controlling massive hemorrhage in which there was no response to conventional measures. It is now considered by some to be potentially the first universal hemostatic agent. However, further prospective, controlled, and adequately powered clinical studies are clearly required. It will be of particular interest to determine the efficacy of rVIIa in conditions such as severe thrombocytopenia, severe von Willebrand disease, severe defects in platelet activation, and severe deficiencies of factors V, X, II, and fibrinogen in which effectiveness would seem to be unlikely based on our current understanding of mechanisms of action of rVIIa.