thiamine + promethazine

Thiamine + promethazine is a combination drug consisting of thiamine (vitamin B1) and promethazine. Thiamine is an essential water-soluble vitamin involved in carbohydrate metabolism and neural function, while promethazine is a first-generation antihistamine of the phenothiazine class with strong sedative, antiemetic, anticholinergic, and antihistaminic properties. Promethazine acts primarily as an antagonist at the histamine H1 receptor but also blocks muscarinic acetylcholine receptors, alpha-adrenergic receptors, serotonin 5-HT2A/2C receptors, dopamine D2 receptors (weakly), and NMDA receptors. The combination may be used in clinical settings where both prevention/treatment of nausea or allergic symptoms (promethazine) and supplementation or treatment/prevention of thiamine deficiency (thiamine) are required.