The effects of two different dosage regimens of sulphinpyrazone on platelet function ex vivo and blood chemistry in man

A serial study of platelet reactivity throughout the first six months after myocardial infarction: its modification by sulphinpyrazone

Platelet reactivity was studied immediately after and throughout the first 6 months following myocardial infarction. Its modification by sulphinpyrazone was observed. Out of 65 consecutive patients admitted to the coronary care unit, ten did not meet the protocol criteria. Fifty five received either placebo or sulphinpyrazone in a double-blind trial for 6 months, treatment being started within 6 days of infarction. Forty four patients completed the study (19 on placebo and 25 on sulphinpyrazone). An additional ten patients commenced treatment within one day of infarction and were studied daily for one week. Platelet hyper-reactivity was demonstrable in all patients at presentation and persisted throughout the 6 months in the control group. This effect was reversed by sulphinpyrazone, the modification of reactivity being established by the third day of treatment.

A direct protective effect of sulphinpyrazone on ischaemic and reperfused rat hearts

Initiation of 60 min ischaemia to rat isolated hearts produced a depression in developed tension and heart rate. Subsequent reperfusion caused a greatly exacerbated creatine phosphokinase (CPK) efflux and limited functional recovery. Sulphinpyrazone (100 ng ml-1 and 1 microgram ml-1) significantly reduced CPK release, particularly after reperfusion, the lower concentration being more effective. A reduction in the mechanical depression during ischaemia and enhanced recovery after reperfusion were seen only with 100 ng ml-1 sulphinpyrazone. Heart rate and coronary perfusion pressure were unaffected by drug treatment. The reduction in reperfusion-induced CPK efflux by 100 ng ml-1 sulphinpyrazone was maximal when the drug was present throughout the perfusion period although some protection was evident when sulphinpyrazone was present either during ischaemia or reperfusion only. An enhanced recovery in contractility was seen only when the drug was present throughout all phases of perfusion. It is suggested that sulphinpyrazone exerts a direct protective effect on the heart particularly during reperfusion. The degree of protection is critically dependent on the concentration of sulphinpyrazone.