4. Mechanism
It is a highly cationic peptide that binds to either heparin or low molecular
weight heparin (LMWH) to form a stable ion pair, which does not have
anticoagulant activity.
The ionic complex is then removed and broken down by the
reticuloendothelial system.
In large doses, protamine sulfate may also have an independent —
however weak — anticoagulant effect.
5. Medical uses
Protamine sulfate is usually administered to reverse the large dose of heparin
administered during certain surgeries, especially heart surgery where anti-coagulation is
necessary to prevent clot formation within the cardiopulmonary bypass pump
apparatus.
A dose of protamine is given, by drip administered over several minutes, once the
patient is off-pump, when extracorporeal circulation and anticoagulation are no longer
needed.
It is also used in gene transfer, protein purification and in tissue cultures as
a crosslinker for viral transduction.
In gene therapy, protamine sulfate has been studied as a means to increase transduction
rates by both viral and nonviral-mediated delivery mechanisms (e.g. utilizing cationic
liposomes).
Protamine is used in insulin aspart protamine and NPH insulin.
