1. Drug Name:

chlorpheniramine

2. Brand Names:

1. 1.Chlor-trimetron, Aller-chlor, Chlor-tripolon, ChlorTabs

3. How Dispensed:

Over-the-counter and prescription

4. Forms:

4mg tablets, 12mg extended-release tablets, oral syrup

5. Drug Type/Class:

Antihistamine

6. Uses for Cats and Dogs:

Used off-label to treat allergic conditions such as itchy skin, vaccine reactions, bee/insect stings, and blood transfusion reactions

7. How it Works:

Chlorpheniramine blocks H1 cellular receptors and prevents their activation by histamine. Histamine is an inflammatory biochemical that causes skin redness, tissue swelling, and itching - many of the symptoms associated with allergic reactions. Histamine is released from a cell type called mast cells and attaches to other cells that have histamine receptors on their surfaces.

There are many types of histamine receptors besides H1 receptors, and histamine is not always the primary mediator of inflammation in pets. This means that antihistamine therapy is not always a reliable option for dogs and cats.

8. Side Effects and/or Signs of Overdose:

Lethargy, sedation, diarrhea, vomiting, anorexia. May cause paradoxical excitement in cats.

9. Drug Interactions:

Do not use with anticoagulants, MAO inhibitors, and other depressant drugs.

10. Cautionary Statements:

Do not use in pets that are hypersensitive to antihistamines. Use caution in pets with angle-closure glaucoma, prostatic hypertrophy, and bladder neck obstruction. Use care in patients with hyperthyroidism, cardiovascular disease, and hypertension.

Read more:

Pet Medication 101: Claritin

Pet Medication 101: Benadryl

Pet Medication 101: Zyrtec

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