diphenhydramine + sodium bicarbonate

Diphenhydramine + sodium bicarbonate is a combination of two agents used primarily in the context of diphenhydramine overdose or toxicity. Diphenhydramine is a first-generation antihistamine that acts as an inverse agonist at the histamine H1 receptor, with additional antimuscarinic and local anesthetic (sodium channel blocking) properties. In overdose, it can cause anticholinergic toxicity and cardiac arrhythmias due to its blockade of cardiac sodium channels. Sodium bicarbonate is an alkalinizing agent commonly used to treat metabolic acidosis and as an antidote for certain drug toxicities involving sodium channel blockade. In cases of diphenhydramine-induced cardiotoxicity (such as wide complex tachycardia), intravenous sodium bicarbonate is administered to reverse QRS widening by counteracting the effects on cardiac sodium channels[2][3][9]. This combination does not represent a marketed pharmaceutical product but rather a therapeutic pairing used in emergency medicine.