Glyburide
Glyburide (also known as glibenclamide) is a **second-generation sulfonylurea** oral antidiabetic agent. In veterinary medicine, it is primarily used as an alternative oral treatment for **non-insulin dependent diabetes mellitus (NIDDM)** in cats. Key clinical points: * **Alternative to Glipizide:** It is typically considered when glipizide is unavailable or when a once-daily dosing regimen is strongly preferred by the owner. * **Insulin is Superior:** While oral hypoglycemics can be trialed, **insulin therapy remains the gold standard** and is generally preferred for feline diabetes. * **Efficacy:** Glyburide may not be effective in cats demonstrating significant insulin resistance or those with depleted pancreatic beta-cell function.
Mechanism: Glyburide lowers blood glucose concentrations by stimulating the secretion of endogenous insulin from functional pancreatic beta cells. **Mechanism of Action:** * Binds to **sulfonylurea receptor 1 (SUR1)** subunits on **ATP-sensitive potassium channels (K-ATP)** in the pancreatic beta-cell membrane. * **K-ATP channel closure** → cell membrane depolarization. * Depolarization triggers the opening of **voltage-dependent calcium channels** → **Calcium influx**. * Increased intracellular calcium promotes the exocytosis of **insulin** granules. **Extrapancreatic Effects:** With long-term administration, glyburide may also enhance insulin activity at post-receptor sites and reduce basal hepatic glucose production.
Dosing by species
- Non-insulin dependent diabetes mellitus (NIDDM) · 0.625 mg (1/2 of a 1.25 mg tablet) · PO · once daily · Initial dose
- Non-insulin dependent diabetes mellitus (NIDDM) · 2.5 mg (total dose) · PO · twice a day · If cat is generally well, weight loss is mild, is not ketoacidotic, and does not have peripheral neuropathy
Doses are a clinical reference for licensed veterinary professionals. Always confirm against the current label and the individual patient.
Routes of administration
Contraindications
- Severe burns
- Severe trauma
- Severe infection
- Diabetic coma or other hypoglycemic conditions
- Major surgery
- Ketosis
- Ketoacidosis or other significant acidotic conditions
Adverse effects
- Vomiting
- Hypoglycemia
- Liver toxicity (icterus, increased ALT/SGPT)
- Allergic skin reactions (reported in humans)
- Arthralgia (reported in humans)
- Bone marrow suppression (reported in humans)
- Cholestatic jaundice (reported in humans)
Drug interactions
- Alcohol · A disulfiram-like reaction (anorexia, nausea, vomiting) is possible
- Azole Antifungals (ketoconazole, itraconazole, fluconazole) · May increase plasma levels of glyburide
- Beta-blockers · May potentiate hypoglycemic effect
- Chloramphenicol · May displace glyburide from plasma proteins
- Cimetidine · May potentiate hypoglycemic effect
- Corticosteroids · May reduce efficacy
- Thiazide Diuretics · May reduce hypoglycemic efficacy
- Isoniazid · May reduce hypoglycemic efficacy
- MAO Inhibitors · May potentiate hypoglycemic effect
- Niacin · May reduce hypoglycemic efficacy
- Phenothiazines · May reduce hypoglycemic efficacy
- Phenytoin · May reduce hypoglycemic efficacy
- Probenecid · May potentiate hypoglycemic effect
- Sulfonamides · May displace glyburide from plasma proteins
Monitoring
- Physical examination (weekly during first month)
- Body weight (weekly during first month)
- Urine glucose and ketones (weekly during first month)
- Serial blood glucose exams (weekly during first month)
- Clinical signs of adverse effects (vomiting, icterus)
- Liver enzymes (ALT/SGPT) occasionally
- Complete Blood Count (CBC) occasionally
Overdose
> **Emergency Warning:** Profound **hypoglycemia** is the greatest concern after an overdose. * In humans, severe hypoglycemia has occurred at relatively low dosages. * **Decontamination:** Gut emptying protocols should be employed when warranted and if the patient is neurologically stable. * **Treatment:** Because its half-life is longer than glipizide, prolonged hypoglycemia may occur. Continuous blood glucose monitoring and treatment with parenteral glucose (IV dextrose) may be required for several days. * **Monitoring:** Massive overdoses may also require additional monitoring (blood gases, serum electrolytes) and supportive therapy.
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.