| Indication | For treatment and relief of symptoms of allergies, hay fever, and colds |
| Pharmacodynamics | In allergic reactions an allergen interacts with and cross-links surface IgE antibodies on mast cells and basophils. Once the mast cell-antibody-antigen complex is formed, a complex series of events occurs that eventually leads to cell-degranulation and the release of histamine (and other chemical mediators) from the mast cell or basophil. Once released, histamine can react with local or widespread tissues through histamine receptors. Histamine, acting on H1-receptors, produces pruritis, vasodilatation, hypotension, flushing, headache, tachycardia, and bronchoconstriction. Histamine also increases vascular permeability and potentiates pain. Dexbrompheniramine is a histamine H1 antagonist (or more correctly, an inverse histamine agonist) of the alkylamine class. It provides effective, temporary relief of sneezing, watery and itchy eyes, and runny nose due to hay fever and other upper respiratory allergies. |
| Mechanism of action | Dexbrompheniramine competitively binds to the histamine H1-receptor. It competes with histamine for the normal H1-receptor sites on effector cells of the gastrointestinal tract, blood vessels and respiratory tract. This blocks the action of endogenous histamine, which subsequently leads to temporary relief of the negative symptoms brought on by histamine. |
| Absorption | Antihistamines are well absorbed from the gastrointestinal tract after oral administration. |
| Volume of distribution | Not Available |
| Protein binding | Not Available |
| Metabolism | Hepatic (cytochrome P-450 system), some renal. |
| Route of elimination | Not Available |
| Half life | 25 hours |
| Clearance | Not Available |
| Toxicity | Signs of an overdose include fast or irregular heartbeat, mental or mood changes, tightness in the chest, and unusual tiredness or weakness. |
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