What is the antidote for heparin?

Protamine is the correct antidote for heparin because it directly counteracts the effects of heparin, which is an anticoagulant medication. Heparin works by inhibiting the formation of clots in the blood, and when there is a need to reverse this anticoagulant effect—such as in cases of excessive bleeding or before surgical procedures—protamine is administered.

Protamine chemically binds to heparin, forming a stable complex that renders heparin inactive, effectively reversing its anticoagulant effects. This mechanism is crucial for ensuring that patients can safely undergo procedures where blood clotting function needs to be restored.

The other substances listed serve entirely different purposes: Deferoxamine is used to treat iron overload, naloxone is an opioid antagonist used to reverse opioid overdose, and sodium bicarbonate is primarily used to treat acidosis. Their functions do not involve the reversal of anticoagulant effects, which highlights why protamine is the suitable option for heparin reversal.