Vetdrugs 2.0Pheniramine maleate is a first-generation H1 antihistamine used for symptomatic relief of selected histamine-mediated allergic manifestations. Veterinary injectable products are used in companion animals and livestock in some regions. Its principal clinical contribution is reduction of urticaria, edema or associated pruritus, with response depending on the mediators driving the reaction.
Group
First-generation H1 antihistamine
Mechanism of Action
Pheniramine binds histamine H1 receptors and stabilizes their inactive state, reducing histamine-mediated vascular permeability, tissue edema and sensory-nerve activation. This can lessen wheal formation and itching in responsive allergic reactions. Central nervous system penetration and antimuscarinic receptor activity contribute additional pharmacologic effects that are distinct from peripheral antihistamine action.
Dose Rates
Cattle
| Use / stage | Dose | Route | Schedule | Instructions |
|---|---|---|---|---|
| Allergic manifestations | 113.75–227.5 mg/animal | IM, IV | Product fixed-volume recommendation for large animals: 5-10 mL of 22.75 mg/mL. Frequency is not specified in the cited product information. |
Horses
| Use / stage | Dose | Route | Schedule | Instructions |
|---|---|---|---|---|
| Allergic manifestations | 113.75–227.5 mg/animal | IM, IV | Product fixed-volume recommendation for large animals: 5-10 mL of 22.75 mg/mL. Frequency is not specified in the cited product information. |
Dogs
| Use / stage | Dose | Route | Schedule | Instructions |
|---|---|---|---|---|
| Allergic manifestations | 11.375–22.75 mg/animal | IM, IV | Product fixed-volume recommendation for small animals: 0.5-1 mL of 22.75 mg/mL. Select within this range for the patient; frequency is not specified. |
Cats
| Use / stage | Dose | Route | Schedule | Instructions |
|---|---|---|---|---|
| Allergic manifestations | 11.375–22.75 mg/animal | IM, IV | Product fixed-volume recommendation for small animals: 0.5-1 mL of 22.75 mg/mL. Select within this range for the patient; frequency is not specified. |
Indications
- Symptomatic treatment of urticaria, allergic skin edema and histamine-associated pruritus in supported companion-animal or livestock species.
- Symptomatic relief of selected insect-bite or drug-associated allergic skin reactions.
- Adjunctive treatment of selected allergic rhinitis, with limited veterinary clinical outcome evidence.
- Adjunctive control of histamine-mediated manifestations during selected acute allergic reactions as part of comprehensive emergency treatment.
Contraindications
- Hypersensitivity; use caution with urinary retention, glaucoma and seizure disorders.
Interactions
- Sedatives and other anticholinergic drugs can increase CNS depression or antimuscarinic effects.
- MAO inhibitors may intensify anticholinergic effects.
Adverse effects
- Sedation, dry mucosae, urinary retention or paradoxical excitation.
Toxicity
Overexposure can cause marked anticholinergic signs, agitation or seizures; provide supportive care.
Preparations
| Preparation | Form | Strength | Route |
|---|---|---|---|
| Avilin VET 22.75 mg/mL Product withdrawal: milk 2 days; meat 7 days. | Injection | 22.75 mg / mL | IM, IV |
Monitoring and Administration
Monitor alertness, heart rate and urinary function. An antihistamine is adjunctive and does not replace adrenaline in anaphylaxis.
The product distinguishes large from small animals without a weight scale; do not reinterpret its fixed volumes as a universal mg/kg dose.