Wednesday February 25, 2009
r-PA in massive PE

Q: For massive PE, fibrinolytic regimens currently in common use include 2 forms of recombinant tissue plasminogen activator, t-PA (alteplase) and r-PA (reteplase). What advantage does r-PA has over t-PA?


Answer: Reteplase (r-PA, Retavase) is a second-generation recombinant tissue-type plasminogen activator. As fibrinolytic agent, it seems to work faster than its forerunner, t-PA (alteplase), and also may be more effective in patients with larger clot burden. Also has been reported more effective than other agents in lysis of older clots. Two major differences help explain these improvements.

1. Compared to alteplase, reteplase does not bind fibrin so tightly, allowing drug to diffuse more freely through clot.
2. Reteplase does not compete with plasminogen for fibrin-binding sites, allowing plasminogen at site of clot to be transformed into clot-dissolving plasmin.

Dose is two 10-U IV boluses, given 30 min apart. In setting of cardiac arrest or impending arrest due to PE, single IV bolus of 20 U can be used.