Cataracts in beagle dogs given diazoxide.

Area of Science:

• Veterinary Toxicology
• Ophthalmology
• Endocrinology

Background:

• Diazoxide is a medication used for various conditions.
• Previous toxicity studies have investigated its effects in animals.
• Understanding dose-dependent side effects is crucial for safe therapeutic use.

Purpose of the Study:

• To evaluate the toxicity of diazoxide in beagle dogs.
• To investigate the occurrence of ocular changes, specifically cataracts, following diazoxide administration.
• To determine the relationship between diazoxide dosage, hyperglycemia, and pancreatic islet cell morphology.

Main Methods:

• Two toxicity studies were conducted in beagle dogs.
• Diazoxide was administered intravenously and orally at various dose levels.
• Ocular examinations were performed to detect lenticular changes (cataracts).
• Blood glucose levels were monitored for hyperglycemia.
• Histopathological examination of pancreatic tissue was conducted post-necropsy.

Main Results:

• Reversible cataracts and lenticular changes were observed in dogs receiving high doses of diazoxide, particularly with prolonged oral administration.
• These ocular changes were associated with dose-dependent hyperglycemia.
• Histological examination revealed vacuolation or absence of islet cells in the pancreas of affected dogs.
• No cataracts were observed at lower doses (e.g., 10-30 mg/kg/day orally).
• The doses causing cataracts in dogs were 10-40 times higher than the suggested human dose.

Conclusions:

• High doses of diazoxide administered daily for extended periods can induce reversible cataracts in beagle dogs.
• The ocular toxicity is likely mediated by diazoxide-induced hyperglycemia and subsequent pancreatic islet cell alterations.
• These findings highlight the importance of dose consideration and monitoring for potential side effects in both animal and human treatments with diazoxide.