Gliclazide !
The sulfonylurea on the WHO essential list: it raises insulin release with less hypoglycemia than glibenclamide.
Updated 2026-11-01
No structure with gliclazide is available; the figure shows glibenclamide, another sulfonylurea that binds the same SUR1 pocket of the KATP channel (hamster SUR1, rat Kir6.2).
Mechanism of action
Gliclazide binds SUR1 and closes the beta-cell KATP channel; depolarization opens calcium channels and insulin is released. It binds more reversibly than glibenclamide and its metabolites are inactive, so hypoglycemia is less frequent, though still possible.
- Binds SUR1 on the beta-cell KATP channel
- The channel closes and the membrane depolarizes
- Calcium channels open and insulin granules are released
- Glucose falls, even when it is already low
Pharmacokinetics
- Absorption
- Oral; also as a modified-release tablet for once-daily use.
- Metabolism
- Extensively in the liver to inactive metabolites.
- Elimination
- Mainly in urine as metabolites.
Indications
- Type 2 diabetes, with diet and exercise, alone or with metformin Type 2 diabetes mellitus →
Adverse effects
Common
- Hypoglycemia
- Weight gain
- Abdominal pain, diarrhea
Contraindications
- Type 1 diabetes and diabetic ketoacidosis
- Severe kidney or liver disease
- Acute porphyria
- Hypersensitivity to gliclazide or other sulfonylureas
Key interactions
- Insulin and other glucose-lowering drugs
- Add to hypoglycemia.
- Beta-blockers
- Can increase the effect and blunt the warning signs of hypoglycemia.
- NSAIDs and salicylates, sulfonamides, fluoroquinolones, oral azole antifungals (miconazole)
- Can increase the glucose-lowering effect and cause severe hypoglycemia.
- Alcohol
- Raises the risk of hypoglycemia.
- Clarithromycin
- Can increase the glucose-lowering effect.
What is monitored
- Capillary glucose
- HbA1c
- Kidney and liver function
Administration and safety
- Oral tablet, given with a meal (usually breakfast); a skipped meal raises hypoglycemia risk.
- Look-alike names: glipizide, glyburide (glibenclamide) and glimepiride are easily confused.
- Often held while the patient is fasting (nil by mouth) in hospital.
Nursing care
- Before: capillary glucose, kidney and liver function, meal intake, age.
- During: signs of hypoglycemia (sweating, tremor, confusion); beta-blockers can mask them.
- After a hypoglycemia episode: glucose is rechecked for many hours, because it can come back.
- Teach: carry fast sugar, avoid skipping meals, limit alcohol.
Pregnancy and breastfeeding
Not usually used in pregnancy; insulin is preferred.
Test yourself
Think of the answer, then tap the question to see it.
Why is gliclazide preferred over glibenclamide in many guidelines?
It causes hypoglycemia less often, because it binds SUR1 more reversibly and its metabolites are inactive.
Which inherited metabolic disease is a contraindication to gliclazide?
Acute porphyria.
Does gliclazide cause weight gain or weight loss?
Weight gain, like other insulin secretagogues, because more insulin favors energy storage.
Related drugs
Related conditions
← Back to the class: Sulfonylureas
Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given.
Sources: Gliclazide: medicine for type 2 diabetes - NHS (NHS, 2026); ATCDDD - ATC/DDD Index (WHO Collaborating Centre for Drug Statistics Methodology, 2026); eEML - Electronic Essential Medicines List (World Health Organization, 2025).
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Representative model, for educational purposes only.