Glipizide Pharmacology

Glipizide, or Glucotrol, is a sulfonylurea used for the treatment of Type 2 Diabetes. Pharmacologically, glipizide acts by stimulating beta-cells in the pancreas to release insulin. Specifically, glipizide will block the opening of ATP-sensitive potassium channels on the plasma membrane of beta-cells on the pancreas. The result of that is depolarization, which then causes stimulation of voltage-sensitive calcium channels, eventually causing the exocytosis of insulin. The increased insulin will then promote the storage of glucose, decreasing the amount of glucose in the blood. 

Due to the pharmacology of glipizide, the concerning adverse drug reactions are hypoglycemia and weight gain. Other adverse drug reactions include diaphoresis, dizziness, syncope, nervousness, anxiety, tremors, and diarrhea. The contraindications include hypersensitivity, Type 1 Diabetes, and DKA. Glipizide is not used as often due to the risk of hypoglycemia and weight gain. Glipizide is usually dosed once daily, but it can be split up if the dose is escalated. There are differences in administration depending on the formulation. For immediate release formulations, glipizide should be taken 30 minutes before meals to ensure that absorption is stable. For extended formulations, it can be given with breakfast or any other meal. 

Of all the sulfonylureas, glipizide is preferred in CKD. Other sulfonylureas, like glyburide, are not preferred due to a decrease in elimination that can result in dose accumulation. In geriatric populations, dosing is less aggressive to lessen the risk of any adverse drug reactions and more specifically hypoglycemia. There’s a risk of cross-reactivity with sulfonamide allergies, but the risk will vary and is low risk. If SJS occurs due to a sulfonamide-containing drug, glipizide likely wouldn’t be recommended.

The drug-drug interactions of glipizide include medications that can increase the risk of hypoglycemia, for example, medications like quinolone antibiotics and B-blockers can mask the symptoms of hypoglycemia. Other interactions include the type where it can counteract the effect of glipizide, for example, medications that can increase blood glucose levels like corticosteroids, antipsychotics such as olanzapine and clozapine, stimulants, and transplant medications like cyclosporine and tacrolimus. There are also CYP interactions that can impact glipizide since it’s metabolized by CYP2C9. More monitoring is warranted when medications that can inhibit CYP2C9, like fluconazole, and medications that can induce CYP2C9, like rifampin, are also given. In cases of overdose, hypoglycemia is most likely to occur. Correction of decreased glucose levels is necessary.

Show notes provided by Chong Yol G Kim, PharmD Student.

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