adrenaline + promethazine + hydrocortisone

This is a combination of three pharmaceutical agents—adrenaline (epinephrine), promethazine, and hydrocortisone—used together primarily as a pretreatment to reduce the risk of acute severe allergic reactions, particularly those associated with antivenom administration following snakebite. - **Adrenaline (epinephrine)** is a sympathomimetic hormone and neurotransmitter that acts on alpha and beta adrenergic receptors, leading to vasoconstriction, bronchodilation, increased cardiac output, and inhibition of further mediator release from mast cells. It is the first-line treatment for anaphylaxis[4][1][2]. - **Promethazine** is a first-generation antihistamine with potent H1 receptor antagonism; it also exhibits anticholinergic, antidopaminergic, antiemetic, sedative-hypnotic effects[3][5][7]. - **Hydrocortisone** is a glucocorticoid corticosteroid that exerts anti-inflammatory and immunosuppressive effects by modulating gene expression through the glucocorticoid receptor[10]. In clinical studies in South Asia involving patients receiving antivenom for snakebite envenoming—a context where acute allergic/anaphylactic reactions are common—this combination was tested as pretreatment. Adrenaline significantly reduced severe adverse reactions to antivenom; however, neither promethazine nor hydrocortisone alone were effective in this setting. Notably, adding hydrocortisone appeared to negate some benefits of adrenaline[1][2][6][8].