# Aminophylline: veterinary dose and monograph

> Aminophylline is a veterinary drug. A methylxanthine bronchodilator — aminophylline is the soluble ethylenediamine salt of theophylline (≈80 % theophylline by weight), giving a parenteral/IV option and an oral bronchodilator for chronic bronchitis, feline asthma and cor… Indications include chronic bronchitis and bronchoconstriction (dogs, cats); feline asthma (oral maintenance bronchodilation); cor pulmonale / right heart disease with bronchospasm. This monograph lists 3 reference doses for dogs, cats and horses, each with route, frequency and source.

Source: https://vetmasterji.com/drugs/aminophylline · Last reviewed: 2026-10-01

## At a glance

- **Drug class:** Veterinary drug
- **Also known as:** Theophylline ethylenediamine, Aminophyllin, Deriphyllin (component)
- **Species with doses:** Dogs, Cats and Horses
- **General dose range:** 10–11 mg/kg PO q8–12h — check the species tables for the indication
- **Routes:** PO, IV
- **Last reviewed:** 1 October 2026

## Indications

- Chronic bronchitis and bronchoconstriction (dogs, cats)
- Feline asthma (oral maintenance bronchodilation)
- Cor pulmonale / right heart disease with bronchospasm
- Adjunct bronchodilation in respiratory distress

## Aminophylline dose by species

Doses are per administration unless stated. mg/kg doses scale with body weight; per-animal, per-quarter and infusion-rate doses are shown as the reference writes them.

### Dogs

*Aminophylline doses for dogs*

| Indication | Dose | Route | Frequency | Duration |
| --- | --- | --- | --- | --- |
| Bronchodilation | 10–11 mg/kg | PO | q8h | — |

- Bronchodilation: Papich 5e: 10 mg/kg q8h IM or IV. Plumb’s p.72: tracheal collapse 11 mg/kg PO, IM or IV three times daily (Fossom); cough 10 mg/kg PO/IV three times daily; acute pulmonary oedema/bronchoconstriction 4–8 mg/kg IV/IM or 6–10 mg/kg PO q8h (Ware). IM injection is painful; give IV slowly. Aminophylline ≈ 80% theophylline — dose on lean weight.

### Cats

*Aminophylline doses for cats*

| Indication | Dose | Route | Frequency | Duration |
| --- | --- | --- | --- | --- |
| Asthma / bronchodilation | 5–6.6 mg/kg | PO | q12h | — |

- Asthma / bronchodilation: Papich 5e: 6.6 mg/kg q12h IM or IV. Plumb’s p.72: aminophylline tablets 6.6 mg/kg PO twice daily (Noone); 5 mg/kg PO twice daily for cough or tracheal collapse; 4–8 mg/kg SC, IM or IV q8–12h for bronchoconstriction with fulminant CHF (Ware).

### Horses

*Aminophylline doses for horses*

| Indication | Dose | Route | Frequency | Duration |
| --- | --- | --- | --- | --- |
| Bronchospasm (RAO) | 5–10 mg/kg | IV | q8–12h | — |

- Bronchospasm (RAO): Papich 5e: RAO 12 mg/kg initially, then 5 mg/kg q12h — IV use causes transient excitement; give slowly. Plumb’s p.72: heaves 5–10 mg/kg PO or IV twice daily (Lavoie) or 4–6 mg/kg PO three times daily; pulmonary oedema 2–7 mg/kg IV q6–12h. Dilute IV doses in ≥100 mL and give no faster than 25 mg/min. ARCI Class 3.

## Contraindications

Significant tachyarrhythmia, hyperthyroidism, severe cardiac disease, and seizure disorders (methylxanthine CNS stimulation). Hepatic impairment (reduced clearance). Rapid IV bolus (arrhythmia/seizure). Concurrent fluoroquinolones/CYP inhibitors (toxicity). Known hypersensitivity.

## Species-specific warnings

> **Caution:** Cats: Lower mg/kg and q12h dosing; cats have a narrow methylxanthine margin — watch for tachycardia, tremor and seizures.

## Adverse effects

- GI upset (vomiting, anorexia)
- CNS stimulation — restlessness, tremor, seizures (toxicity)
- Tachycardia / arrhythmias
- Polyuria/polydipsia (mild diuretic effect)

## Drug interactions

- Fluoroquinolones (enrofloxacin/ciprofloxacin), cimetidine, macrolides, fluconazole: inhibit clearance → theophylline toxicity (reduce dose)
- Phenobarbital/rifampin: induce metabolism → reduced levels
- Beta-agonists: additive bronchodilation and cardiac stimulation
- Beta-blockers: antagonise bronchodilation
- Halothane: increased arrhythmogenicity

## Pregnancy and lactation

Crosses the placenta; use cautiously if needed. Methylxanthines stimulate the fetus/neonate.

## Monitoring

- Clinical bronchodilator response and respiratory effort
- Signs of toxicity (vomiting, tremor, tachycardia) — dose-limiting
- Serum theophylline levels where available (narrow index)
- Review interacting drugs (especially fluoroquinolones)

## Toxicity and overdose

Narrow therapeutic index — toxicity (vomiting, tachyarrhythmia, hyperexcitability, tremor, seizures) appears at levels not far above therapeutic, and rises sharply with interacting drugs (e.g. enrofloxacin) or hepatic impairment. Severe overdose can be life-threatening (refractory arrhythmia, seizures).

Management: No specific antidote. Decontaminate (multi-dose activated charcoal enhances elimination); control seizures with benzodiazepines, treat tachyarrhythmia (β-blocker, e.g. esmolol/propranolol), correct hypokalaemia, IV fluids and intensive monitoring. Severe cases may need haemodialysis/charcoal haemoperfusion.

## Clinical pearls

- Aminophylline ≈ 80 % theophylline — convert carefully when switching between salts to avoid under/over-dosing
- Narrow margin: the classic toxicity trap is co-prescribing enrofloxacin (or cimetidine), which raises theophylline to toxic levels — reduce the dose
- A useful add-on bronchodilator for feline asthma/canine bronchitis, but pair asthma control with an anti-inflammatory (corticosteroid)
- Give IV slowly; rapid injection causes arrhythmia and seizures

## Mechanism of action

As theophylline it (1) non-selectively inhibits phosphodiesterase (raising cAMP → bronchial smooth-muscle relaxation) and (2) antagonises adenosine receptors (bronchodilation, CNS/cardiac stimulation). It also improves diaphragmatic contractility and mucociliary clearance. The same mechanisms produce its narrow-margin cardiac and CNS stimulant toxicity.

## Formulations and products

- 100 mg tablet
- Injection 25 mg/mL
- Deriphyllin — Etophylline + Theophylline tablet/injection, Tablet / injection (human-label)
- Aminophylline injection — 25 mg/mL, Injection (human-label)

## Storage

Tablets/injection: 15–30 °C, protect from light; do not use discoloured injection.

## Before you use this dose

> **Caution:** Reference doses for veterinary professionals. Confirm the dose against the product label, the patient’s condition, current guidance and local regulations before use; the attending veterinarian remains responsible for every clinical decision.

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## Frequently asked questions

### What is the dose of Aminophylline for dogs?

Reference doses for Aminophylline in dogs: 10–11 mg/kg PO q8h (Bronchodilation). Confirm against the label and the patient before use.

### What is the dose of Aminophylline for cats?

Reference doses for Aminophylline in cats: 5–6.6 mg/kg PO q12h (Asthma / bronchodilation). Confirm against the label and the patient before use.

### What is the dose of Aminophylline for horses?

Reference doses for Aminophylline in horses: 5–10 mg/kg IV q8–12h (Bronchospasm (RAO)). Confirm against the label and the patient before use.

### When should Aminophylline not be used?

Significant tachyarrhythmia, hyperthyroidism, severe cardiac disease, and seizure disorders (methylxanthine CNS stimulation). Hepatic impairment (reduced clearance). Rapid IV bolus (arrhythmia/seizure). Concurrent fluoroquinolones/CYP inhibitors (toxicity). Known hypersensitivity.

### What are the side effects of Aminophylline in animals?

GI upset (vomiting, anorexia); CNS stimulation — restlessness, tremor, seizures (toxicity); Tachycardia / arrhythmias; Polyuria/polydipsia (mild diuretic effect).

## Sources

- Plumb's Veterinary Drug Handbook
- Merck Veterinary Manual, 11th edition
- Papich, Papich Handbook of Veterinary Drugs, 5th edition

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