Dose range: 100 to 450 mg/day. IV route: three doses of 5 mg Metoprolol administered at intervals of 2 minutes time. Oral route: if the patient gives no sign of complication from the IV route, a total of 15 mg, then a tablet of 50 mg in 6 hour block should start immediately after the IV dose.
â¢ ANTIHISTAMINE (noun) The noun ANTIHISTAMINE has 1 sense: 1. a medicine used to treat allergies and hypersensitive reactions and colds; works by counteracting the effects of histamine on a receptor site. Familiarity information: ANTIHISTAMINE used as a noun is very rare.
Histamine: A substance that plays a major role in many allergic reactions, dilating blood vessels and making the vessel walls abnormally permeable.Histamine is part of the body's natural allergic response to substances such as pollens.Antihistamines work by preventing the release of histamine from certain cells (mast cells) thereby blocking the allergic reaction.istamine is part of the body's natural allergic response to substances such as pollens. Antihistamines work by preventing the release of histamine from certain cells (mast cells) thereby blocking the allergic reaction.