Chlorpheniramine is a histamine H1 receptor antagonist with an IC75 value of 0.0016 μg/ml for reversal of histamine-induced spasms in isolated guinea pig ileum. It protects against intravenous histamine-induced death (PD50 = 0.15 mg/kg) and delays induction of aerosolized histamine-induced coughing (ED100sec = 0.44 mg/kg) in guinea pigs. Chlorpheniramine (20 mg/kg, i.p.) prevents histamine-induced passive cutaneous anaphylaxis (PCA) in rabbits. It also reduces respiratory resistance and hypersecretion of tracheobronchial fluid in a dog model of histamine-induced asthma. Formulations containing chlorpheniramine have been used in the treatment of seasonal allergies.
(±)-Chlorpheniramine maleate salt has been used:
- as H1 receptor antagonist to determine the receptor function
- to block the effect of compound 48/80 on plasma IGF-I
- as a standard for fast sensing and determination by sequential injector coupled with potentiometer
An antagonist of the histamine H1-receptor
ChEBI: Chlorpheniramine maleate is an organic molecular entity.
Trimeton (Schering-Plough); Teldrin (GlaxoSmithKline).
Chlorpheniraminemaleate, (±)2-[p-chloro-α-[2-dimethylamino)ethyl]benzyl]pyridine bimaleate (Chlor-Trimeton), is a white crystallinepowder that is soluble in water (1:3.4), in alcohol(1:10), and in chloroform (1:10). It has a pKa of 9.2, and anaqueous solution has a pH between 4 and 5. Chlorination ofpheniramine in the para position of the phenyl ring increasespotency 10-fold with no appreciable change in toxicity.Most of the antihistaminic activity resides with thedextro isomer (see under “Dexchlorpheniramine Maleate” ).The usual dose is 2 to 4 mg 3 or 4 times a day. It has a halflifeof 12 to 15 hours.
Odorless white crystalline solid or white powder with a bitter taste. pH (2% aqueous solution) 5. pH (1% aqueous solution) 4-5.
A halogenated amine, ester. Amines are chemical bases. They neutralize acids to form salts plus water. These acid-base reactions are exothermic. The amount of heat that is evolved per mole of amine in a neutralization is largely independent of the strength of the amine as a base. Amines may be incompatible with isocyanates, halogenated organics, peroxides, phenols (acidic), epoxides, anhydrides, and acid halides. Flammable gaseous hydrogen is generated by amines in combination with strong reducing agents, such as hydrides. Esters react with acids to liberate heat along with alcohols and acids. Strong oxidizing acids may cause a vigorous reaction that is sufficiently exothermic to ignite the reaction products. Heat is also generated by the interaction of esters with caustic solutions. Flammable hydrogen is generated by mixing esters with alkali metals and hydrides.
Flash point data for Chlorpheniramine maleate are not available; however, Chlorpheniramine maleate is probably combustible.
Chlorpheniramine maleate (CPM) can prevent rhinitis and urticaria. It is used to cure several allergic conditions. This antihistamine is used in small-animal veterinary practices.
Poison by ingestion, intravenous, and subcutaneous routes. Experimental reproductive effects. Used as an antihistamine. Mutation data reported. When heated to decomposition it emits very toxic fumes of Cland NOx.
Veterinary Drugs and Treatments
Antihistamines are used in veterinary medicine to reduce or help
prevent histamine
mediated adverse effects. Chlorpheniramine
is one the more commonly used antihistamines in the cat for the
treatment of pruritus. It may also be of benefit as a mild sedative in
small animals due to its CNS depressant effects.
4 to 6 mg PO q4–6h. Maximum daily dose is 24 mg for adults
and children 12 years or older. Found frequently in combination with
acetaminophen and pseudoephedrine.
