The nurse is preparing to administer protamine sulfate for which of the following medication overdoses?

A. Hydralazine (Apresoline) is an antihypertensive medication and is not treated with protamine sulfate. B. Diphenhydramine (Benadryl) is an antihistamine, and protamine sulfate is not used for its overdose. C. Coumadin (Warfarin) is an anticoagulant, but protamine sulfate specifically reverses heparin, not warfarin. D. Protamine sulfate is an antidote used to reverse the effects of heparin, a blood thinner.