Some of the views expressed in the following notes on newly approved products should be regarded as preliminary, as there may have been limited published data at the time of publication, and little experience in Australia of their safety or efficacy. However, the Editorial Executive Committee believes that comments made in good faith at an early stage may still be of value. Before new drugs are prescribed, the Committee believes it is important that more detailed information is obtained from the manufacturer's approved product information, a drug information centre or some other appropriate source.

Rapilysin (Boehringer Mannheim)
vials containing 10 units for reconstitution

Indication: myocardial infarction

Thrombolytic therapy is a key part of the management of myocardial infarction. Streptokinase and tissue plasminogen activator (t-PA) are already available and are now joined by reteplase. This new product is a modified form of tissue plasminogen activator. Reteplase is a recombinant product which has a longer half-life than t-PA. This enables reteplase to be given by injection rather than infusion. Two injections are given slowly, 30 minutes apart. This reduces plasma fibrinogen concentrations by 75-90%. The concentrations of fibrinogen return to normal within 48 hours.

Reteplase has been compared with streptokinase in patients with acute myocardial infarction.1 In this trial,3004 people received reteplase and 3006 received streptokinase. The patients were also given aspirin and warfarin. Within 35 days of their infarction, 9-10%of the patients in each group had died. Strokes and bleeding complications were similar in each group. This trial suggests that reteplase is as effective as streptokinase. Although the trial included patients presenting up to 12hours after infarction, reteplase has only been approved for use within 6 hours.

The contraindications to reteplase are similar to those of other thrombolytic agents e.g. severe hypertension, recent surgery or stroke. The method of elimination is unknown so the drug is contraindicated in patients with liver or renal dysfunction.

The most common adverse events are bleeding at the injection site and hypotension. Other adverse effects include internal bleeding and arrhythmias.

Reteplase is easier to give than tissue plasminogen activator, but it is unlikely to be preferred if it is significantly more expensive than streptokinase.