Lack of efficacy of nafazatrom, a novel anti-thrombotic compound, in patients with coronary artery disease

Effect of nafazatrom on platelet function and release: relationship to symptomatic episodes in patients with peripheral vascular disease

We studied the effect of nafazatrom on plasma prostacyclin (PGI2) levels, platelet function, and thromboxane B2 (TxB2), and 12-hydroxy-eicosatetraenoic acid (12-HETE) production and clinical improvement in 12 patients with peripheral vascular disease (PVD) by means of a double-blind crossover trial of placebo, 800 or 1600 mg of nafazatrom four times daily for 1 week, with intervening 2-week washout periods. Plasma PGI2 levels were measured as 6-keto-PGF1 alpha by radioimmunoassay. Platelet function ex vivo was measured as collagen and adenosine diphosphate (ADP)-induced platelet aggregation, release of 12-HETE and thromboxane A2 (measured as TxB2), and was determined by high-pressure liquid chromatography (HPLC) and radioimmunoassay, respectively. The plasma 6-keto-PGF1 alpha levels were unaffected by nafazatrom treatment (p greater than 0.25). Nafazatrom treatment had no effect on TxB2 production, but significantly altered the production of the platelet 12-HETE (p less than 0.05). There was a significant association between the changes in 12-HETE production and clinical improvement. These results suggest that the mechanism of action of nafazatrom is in part related to the inhibition of platelet function via the lipoxygenase pathway, independent of PGI2 stimulation.

Failure of nafazatrom to reduce infarct size and arrhythmias in a porcine model of acute coronary occlusion

The effects of nafazatrom (10 mg/kg, b.i.d., orally for 2 days preoperatively; 10 mg/kg, intraduodenally, 30 min before coronary occlusion) on hemodynamics and arrhythmias were assessed in a group of drug-treated anesthetized pigs and compared with the effects in animals that received the drug vehicle and were treated identically. Infarct size (triphenyl-tetrazolium method) of the left anterior descending coronary artery was 24.4 +/- 2.4% of the left ventricle in nafazatrom-treated hearts after 2 h of occlusion and 26.2 +/- 3.2% in control hearts. Blood pressure, heart rate, left ventricular systolic and end-diastolic pressure, cardiac output and stroke volume were not different between the groups during cardiac insult. There were no differences in the number of premature ventricular contractions, arrhythmia and tachycardia, and ventricular fibrillation. It is concluded that short-term administration of the 5-lipoxygenase inhibitor nafazatrom had no effect on infarction, hemodynamics or arrhythmias in the acutely ischemic porcine myocardium.