Gliclazide

Gliclazide is an oral medication prescribed to help control Type 2 diabetes mellitus. It belongs to the class of drugs known as sulfonylureas and works by increasing the release of insulin from the pancreas, which helps lower blood sugar levels. Gliclazide also improves the body's sensitivity to insulin and reduces glucose production in the liver. Gliclazide was first approved in 1977. It has since been approved for use in many countries, including the United States, European Union, and other regions for the treatment of type 2 diabetes.

BRAND NAMES

Diamicron: Primarily used to manage blood sugar levels in people with type 2 diabetes. Available in both immediate-release and extended-release formulations

Glibenese: A generic form of gliclazide also used to manage type 2 diabetes by improving insulin secretion and sensitivity.

Gliclazide M: A formulation of gliclazide used for controlling blood glucose levels in people with type 2 diabetes, available in both immediate-release and extended-release forms.

Glizid: It is used in the treatment of type 2 diabetes to control blood sugar by stimulating insulin production from the pancreas

MECHANISM OF ACTION

Gliclazide works by stimulating the release of insulin from the pancreas through binding to sulfonylurea receptors on beta cells. This action closes ATP-sensitive potassium channels, leading to cell depolarization, calcium influx, and insulin secretion. It also improves insulin sensitivity in peripheral tissues and may reduce liver glucose production. These combined actions help lower blood sugar levels in people with Type 2 diabetes.

PHARMACOKINETICS

Absorption: Gliclazide is well absorbed from the gastrointestinal tract after oral administration. Its peak plasma concentration occurs about 4–6 hours after ingestion.

Distribution: It is widely distributed in the body and has a high protein binding rate (about 95%).

Metabolism: Gliclazide is extensively metabolized in the liver to inactive metabolites, primarily through the cytochrome P450 enzyme system (mainly CYP2C9).

Excretion: The metabolites are primarily excreted in the urine. Only a small amount of unchanged gliclazide is found in the urine. The elimination half-life is approximately 10–12 hours, which supports once or twice-daily dosing.

DOSAGE AND ADMINISTRATION

The typical dosage and administration of gliclazide for Type 2 diabetes is:

Starting Dose:

Usually, the starting dose is 40–80 mg once daily, taken with breakfast.

Maintenance Dose:

The dose can be gradually increased, depending on blood glucose levels, up to a maximum of 320 mg per day, typically divided into one or two doses.

Administration:

Gliclazide should be taken with food (preferably with breakfast) to reduce the risk of hypoglycemia.

Combination:

Gliclazide can be used alone or in combination with other antidiabetic agents, including metformin, insulin, or thiazolidinediones, if necessary.

DRUG INTERACTIONS

• Other antidiabetics: Increased risk of hypoglycemia.
• Beta-blockers: May mask hypoglycemia symptoms.
• CYP450 inhibitors/inducers: Can affect gliclazide levels (e.g., fluconazole increases, rifampin decreases).
• Anticoagulants: Increased bleeding risk.
• Diuretics/corticosteroids: May reduce gliclazide effectiveness.
• Alcohol: Increased hypoglycemia risk.

CONTRAINDICATIONS

• Type 1 diabetes: It is not effective for insulin-dependent diabetes.
• Diabetic ketoacidosis: Gliclazide is not suitable in this condition.
• Severe renal or hepatic impairment: It may require dose adjustments or alternative treatments.
• Hypersensitivity to gliclazide or sulfonylureas: Allergic reactions may occur.
• Pregnancy and breastfeeding: Gliclazide is not recommended during pregnancy or breastfeeding unless advised by a healthcare provider.

SIDE EFFECTS

Common side effects of gliclazide:

• Hypoglycemia: Low blood sugar.
• Gastrointestinal issues: Nausea, abdominal pain.
• Weight gain
• Skin reactions: Rash, itching.
• Dizziness,
• Headache

Serious side effects:

• Severe hypoglycemia (confusion, seizures).
• Liver issues: Jaundice

TOXICITY

• Severe hypoglycemia: Leading to confusion, seizures, or unconsciousness.
• Liver damage: Rarely, jaundice may occur.
• Gastrointestinal symptoms: Nausea, vomiting.
• Treatment: Immediate glucose or intravenous dextrose is needed. Seek medical attention for overdose.