Aminophylline
Theophylline ethylenediamine
Also known as: Aminophylline · Theophylline ethylenediamine
Reviewed by the VetSheet Veterinary TeamUpdated Apr 5, 2026Evidence-based veterinary reference
Doses are a clinical reference for licensed veterinary professionals. Always confirm against the current label and the individual patient.
Dosing by species
🌎 NA — North America🌍 EU — Europe
Dogs
| Indication | Dose | Route | Frequency | Duration | Region |
|---|---|---|---|---|---|
| Bronchodilation | 10 mg/kg | PO | q8h | — | 🌍 EU |
- Bronchodilation: Or slowly i.v. (diluted) for emergency bronchodilation
Cats
| Indication | Dose | Route | Frequency | Duration | Region |
|---|---|---|---|---|---|
| Bronchodilation | 5 mg/kg | PO | q12h | — | 🌍 EU |
| Emergency bronchodilation | 2-5 mg/kg | IV | single dose | — | 🌍 EU |
- Emergency bronchodilation: Administer slowly and diluted
Doses are a clinical reference for licensed veterinary professionals. Always confirm against the current label and the individual patient.
Overview
Aminophylline is a methylxanthine bronchodilator used primarily in the treatment of small airway disease. It is a stable mixture of theophylline and ethylenediamine (100 mg of aminophylline is equivalent to 79 mg of theophylline). The drug has a low therapeutic index and should be dosed on a lean body weight basis.
Clinical Warning: Administer with extreme caution in patients with severe cardiac disease, gastric ulcers, hyperthyroidism, renal or hepatic disease, severe hypoxia, or severe hypertension.
Mechanism of action
Aminophylline acts via multiple pharmacological pathways:
- Inhibition of phosphodiesterase (PDE) → increased intracellular cAMP.
- Alteration of intracellular calcium levels.
- Release of endogenous catecholamines.
- Antagonism of adenosine and prostaglandin receptors.
These mechanisms collectively lead to bronchodilation, enhanced mucociliary clearance, stimulation of the respiratory centre, increased sensitivity to PaCO2, increased diaphragmatic contractility, stabilization of mast cells, and a mild inotropic and diuretic effect.
Safety & warnings
Contraindications
- Patients with a known history of arrhythmias
- Patients with a known history of seizures
Adverse effects
- Vomiting
- Diarrhoea
- Polydipsia (PD)
- Polyuria (PU)
- Reduced appetite
- Tachycardia
- Arrhythmias
- Nausea
- Twitching
- Restlessness
- Agitation
- Excitement
- Convulsions
- Hyperaesthesia (especially in cats)
- Intense local pain (if given IM)
Precautions
- Low Therapeutic Index: Must be dosed carefully based on lean body weight.
- Therapeutic Monitoring: Target plasma aminophylline values are 5-20 μg/ml.
- Administration Warning: Do NOT mix aminophylline in a syringe with other drugs.
- Route Warning: Causes intense local pain when given IM; this route is very rarely used or recommended.
- Adverse Effects: Most adverse effects are dose-dependent and related to toxic serum concentrations. Modified-release preparations may decrease the severity of these effects.
Drug interactions
May increase serum levels of aminophylline
May increase serum levels of aminophylline
May increase serum levels of aminophylline
May increase serum levels of aminophylline
May increase serum levels of aminophylline
May decrease the serum concentration of aminophylline
Aminophylline may decrease the effects of pancuronium
May antagonize each other's effects
Increased incidence of cardiac dysrhythmias
Increased incidence of seizures
Monitoring
- Plasma aminophylline levels (Therapeutic range: 5-20 μg/ml)
- Heart rate and rhythm (ECG if arrhythmias suspected)
- CNS signs (agitation, twitching, seizures)
- Clinical response (respiratory rate and effort)
Overdose
Overdose is directly related to toxic serum concentrations. Clinical signs of toxicity include severe vomiting, tachycardia, cardiac arrhythmias, extreme agitation, hyperaesthesia (especially in cats), and convulsions/seizures. Treatment is supportive and symptomatic.
Available products
Formulations
- Injectable: 25 mg/ml solution
- Oral: 100 mg tablet
Human-labeled
- Aminophylline 25 mg/ml injectable solution
- Aminophylline 100 mg tablet
Regulatory status
POM (Prescription Only Medicine)
POM-V
No regulatory data for: 🇺🇸 US · 🇭🇰 HK · 🇹🇼 TW · 🇯🇵 JP · 🇰🇷 KR · 🇦🇺 AU
Storage & stability
Do not mix aminophylline in a syringe with other drugs.
Client information
This medication is used to help your pet breathe easier by opening up the airways in the lungs.
- Give exactly as prescribed: This drug has a narrow safety margin, meaning giving too much can easily cause toxicity.
- Side effects to watch for: Contact your vet immediately if you notice vomiting, extreme restlessness, rapid heart rate, twitching, or seizures.
- Increased thirst/urination: Your pet may drink and urinate more than usual; ensure they always have access to fresh water.
- Do not crush or chew: If using modified-release tablets, they must be given whole.
VetSheet drug reference is intended for licensed veterinary professionals as a clinical decision-support aid, not a substitute for professional judgement or the manufacturer’s current label.