What is the main purpose of using protamine?

The primary function of protamine is to act as an antidote for heparin. Heparin is an anticoagulant, which means it prevents blood from clotting. This property makes it useful in various medical situations, such as during surgeries or in treating certain blood clotting disorders. However, if a patient receives too much heparin or if anticoagulation needs to be reversed quickly (for example, before surgery or in case of a bleeding episode), protamine is administered. Protamine works by binding to heparin and neutralizing its effects, thereby restoring the blood's ability to clot.

The other options provided do not align with the pharmacological role of protamine. It is not used to treat iron overdoses, nor is it indicated for managing head lice or snake bites. Each of these conditions requires different treatment modalities, typically involving other specific medications or interventions.