Aminophylline

From Dog

Aminophylline and theophylline are non-selective adenosine receptor antagonists and phosphodiesterase inhibitors that causes bronchodilation and pulmonary vasodilation in dogs[1].

This drug is a bronchodilator, causing relaxation of proximal and distal airways, similar in effect to terbutaline and diltiazem, but whose mechanism of action differs[2].

This drug significantly reduces circulating levels of epinephrine, an effect counteracted by propranolol[3].

They are sometimes used as an adjunct therapy in dogs with acute tracheal collapse[4], pulmonary interstitial fibrosis, respiratory distress syndrome, pulmonary hypertension[5] and early stages of congestive heart failure[6].

Toxicity associated with overdosing or accidental ingestion of large quantities of aminophylline have occurred in dogs, which usually present with tachyarrhythmias, dyspnea and collapse. These effects can be mitigated by propranolol or landiolol[7].

Recommended dose rate for aminophylline in dogs is 10 mg/kg given once or twice daily[8].

References

  1. Jagers JV et al (2009) Aminophylline increases ventilation and diaphragm contractility in awake canines. Respir Physiol Neurobiol 167(3):273-280
  2. Akhtar S et al (1999) Differential bronchodilatory effects of terbutaline, diltiazem, and aminophylline in canine intraparenchymal airways. Crit Care Med 27(8):1551-1556
  3. Hirota K et al (2001) A comparison of the relaxant effects of olprinone and aminophylline on methacholine-induced bronchoconstriction in dogs. Anesth Analg 93(1):230-233
  4. Radlinsky MA & Fossum TW (2000) Tracheal collapse in a young boxer. J Am Anim Hosp Assoc 36(4):313-316
  5. Hirota K et al (2002) Spasmolytic effects of colforsin daropate on serotonin-induced pulmonary hypertension and bronchoconstriction in dogs. Acta Anaesthesiol Scand 46(3):297-302
  6. Minamino T et al (1985) Bidirectional effects of aminophylline on myocardial ischemia. Circulation 92(5):1254-1260
  7. Takahashi S et al (2000) Modifications of the hemodynamic consequences of theophylline intoxication with landiolol in halothane-anesthetized dogs. Can J Anaesth 47(3):265-272
  8. Bach JE et al (2004) Evaluation of the bioavailability and pharmacokinetics of two extended-release theophylline formulations in dogs. J Am Vet Med Assoc 224(7):1113-1119