Chlorpheniramine Meleate

Anti-histamine

View Brand Names (2)

Dose and dosage

Dog

a) 4–8 mg (maximum of 0.5 mg/kg) PO q8–12h PO; many clinicians use as adjunctive treatment of chemotherapy of mast cell tumors (Papich 2000)
b) 4–12 mg (total dose) two to three times daily (MacDonald 2002)
c) 2–8 mg (total dose) per dog PO every 12 hours, not to exceed 0.5 mg/kg every 12 hours (Cote 2005)
For pruritus:
a) As a trial for pruritus in atopic dogs: 0.4–0.8 mg/kg two to three times daily (Rosychuk 2002)
b) 0.2–0.8 mg/kg PO 2-3 times a day (Marsella 2008) As a mild sedative:
a) 0.22 mg/kg PO q8h; 4–20 mg (total dose per day) divided q8–12h (Overall 2000)
Cat

a) 2 mg (total dose) per cat PO every 12 hours (Cote 2005)
b) 2–4 mg per cat q12–24h PO (Hnilica 2003), (Rosychuk 2002)
c) Most common dosage in cats is: 2 mg per cat two to three times daily (MacDonald 2002)
For pruritus:
a) 2–4 mg/cat twice daily; rarely may be maintained on once daily dosing. Palatability may be enhanced by dipping the split tablet into tuna fish “juice”, butter or petrolatum; placing split tablets into empty gelatin capsules or sprinkling or mixing timed release beads (partial contents of an 8 mg capsule) with food. (Messinger 2000)
b) 0.5–2 mg (total dose; ¼ - ½ of a 4 mg tablet) PO 2-3 times per day (Marsella 2008)
As a mild sedative:
a) 1–2 mg per cat q12–24h (low dose), 2–4 mg per cat PO q12–24h (high dose) (Overall 2000)
Birds (Other)

a) One 4 mg tablet in one cup (240 mL; 8 oz.) of bottled water to be used as drinking water; changed daily. (Clubb 2009)
Ferrets

a) 1–2 mg/kg PO 2–3 times a day (Williams 2000)
Cattle

0.4-0.5mg/kg body weight 
Horse

0.4-0.5mg/kg body weight 
Sheep and Goat

0.4-0.5mg/kg body weight 

Applications: Dermatitis, Eczema, Insect Bites, Photodermatitis, Rhinitis, Skin Edema, Stomatitis, Tail Eczema, Urticaria, toxic hoof horns, Serum Shock, Paresis, puerperal toxemia, Pulmonary Edema, Pulmonary Emphysema, Toxic Hypopepsia

Antimuscarinic effects (atropine-like effects) are common. Do not use in conditions for which anticholinergic drugs may be contraindicated, such as glaucoma, ileus, or cardiac arrhythmias.

Antihistamine (H1-blocker). Similar to other antihistamines, it acts by blocking the H1 receptor and suppresses inflammatory reactions caused by histamine. The H1-blockers have been used to control pruritus and skin inflammation in dogs and cats, but efficacy for these indications has not been established. Other commonly used antihistamines include clemastine, chlorpheniramine, diphenhydramine, cetirizine, and hydroxyzine.

humans or animals receiving chlorpheniramine and may be of significance in veterinary patients:
ANTICOAGULANTS (heparin, warfarin): Antihistamines may partially counteract the anticoagulation effects of heparin or warfarin
MAO INHIBITORS (including amitraz, and possibly selegiline): May prolong and exacerbate anticholinergic effects
OTHER CNS DEPRESSANT DRUGS: Increased sedation can occur

Antihistamines have a high margin of safety. Sedation is the most common side effect, which is the result of inhibition of histamine N-methyltransferase. Sedation may also be attributed to blocking of other CNS receptors such as those for serotonin, acetylcholine, and alpha-receptors. Antimuscarinic effects (atropine-like effects) also are common, such as dry mouth and decreased GI secretions.