(Synonymous with theophylline ethylenediamine)

Brands:

Aminophylline, Phyllocontin, Truphylline

Availability

• Aminophylline tablets: 100 mg (theophylline equivalent = 78.9 mg),
  and 200 mg (theophylline equivalent=158 mg).
• Controlled released tablets: 225 mg
• Aminophylline injectable: 25 mg/mL (theophylline equivalent = 19.7 mg/mL)
• Aminophylline oral liquid: 105 mg/5ml (theophylline equivalent = 90 mg/5ml)

Pharmacology

A bronchodilator, aminophylline is a derivative of theophylline. Both aminophylline and theophylline are methylxanthines and are derived from the group called Xanthines. The drug aminophylline differs somewhat in its structure from theophylline in that it contains ethylenediamine, as well as more molecules of water. Aminophylline tends to be a less potent and shorter acting than theophylline.

Drugs in the Xanthine group relax smooth muscle particularly bronchial muscle, stimulate cardiac muscle and the central nervous system, and produce diuresis. They also cross the placental barrier.

These drugs can be given orally, although absorption may be slow and not as effective as when given parenterally.

The methylxanthines are partly metabolized in the liver and excreted in the urine.

Indications

Used as a bronchodilator in reversible airway obstruction.

May be used in cases of Pulmonary edema and pulmonary congestion secondary to heart failure. Helpful in rats with CRD (chronic respiratory disease) and pneumonia.

Drug Interactions or Contraindications

• Has synergistic toxicity with sympathomimetics such as ephedrine.
• Erythromycin, ciprofloxacin/enrofloxacin, clindamycin, and other macrolides may increase aminophylline concentrations.

Adverse Reactions

CNS: nervousness,restlessness,seizures

CV: tachycardia, arrhythmias (increased and or irregular heart rate)

GI: gastric irritation

GU: polyuria (increased urine output)

Skin: itching

Dosage Recommendations

2.5 mg/lb to 5 mg/lb, PO or SQ, BID or TID  ⁴

or

10 mg/kg, PO, q12hr to q24hr  ^37, 41, 44

*Note: the injectable may be given orally.

Considerations

• In most cases serum levels do not need to be monitored in the pet rat. Fortunately, serum levels of aminophylline have been found to correlate fairly equal, in dose dependent manner, with what is therapeutic and with what is toxic.
• Make fluids available since aminophylline will increase urine output.
• Do not give chocolate, colas, or caffeine, as this may increase the effect of the drug.
• Can cause panic attack in rats because of its stimulant effect.
• Use recommended nebulizers with a particle size of 0.5-5 micrometer when nebulizing bronchodilators, mucolytics or antimicrobials in rats. Nebulizers with a larger particle size that are used for humans, or small animals, will not be as effective in delivering the medication to the rat.
• Aminophylline injectable should be stored at 20°C to 25°C (68°F to 77°F) and protected from freezing and light. Injectables should not be used if it shows precipitate (crystals) in solution.