Aminophylline: veterinary dose and monograph

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

• 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

• 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

• 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

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

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