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[Pharmacology](https://durgical.com/en/pharmacology/) · [Sulfonylureas](https://durgical.com/en/pharmacology/classes/sulfonylureas/)

# Gliclazide

The sulfonylurea on the WHO essential list: it raises insulin release with less hypoglycemia than glibenclamide.

Updated 2026-11-01

- Class: [Sulfonylureas](https://durgical.com/en/pharmacology/classes/sulfonylureas/)
- Ion channel: Sulfonylurea receptor 1 (SUR1) of the KATP channel
- ATC code: A10BB09
- WHO Model List of Essential Medicines

## ⚠ High-alert medication

An error with this medicine can cause serious harm: double checks and protocols are used.

⇅**Sulfonylurea receptor 1 (SUR1) of the KATP channel**Gliclazide

ⓘ 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).

**Target in 3D:** Sulfonylurea receptor 1 (SUR1) of the KATP channel. PDB structure 6BAA (RCSB PDB, public domain). [View the structure at RCSB PDB](https://www.rcsb.org/structure/6BAA) · Drag to rotate · pinch to zoom

## 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 →](https://durgical.com/en/conditions/type-2-diabetes-mellitus/)

## Adverse effects

### Common

- Hypoglycemia
- Weight gain
- Abdominal pain, diarrhea

### Serious (rare, important)

- Severe hypoglycemia
- Hemolytic anemia in G6PD deficiency (sulfonylurea class)
- Allergic reactions, including anaphylaxis (rare)

## 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.

## Memory aid

Gliclazide is the 'gentle' sulfonylurea: same SUR1 switch, lighter touch and no active leftovers, which is why WHO chose it.

## 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.

[Add to my cards (3)](https://durgical.app/estudiar/?add=/en/pharmacology/gliclazide/)

## Related drugs

- [Glibenclamide](https://durgical.com/en/pharmacology/glibenclamide/)
- [Glimepiride](https://durgical.com/en/pharmacology/glimepiride/)
- [Glipizide](https://durgical.com/en/pharmacology/glipizide/)

## Related conditions

- [Type 2 diabetes mellitus](https://durgical.com/en/conditions/type-2-diabetes-mellitus/)

[← Back to the class: Sulfonylureas](https://durgical.com/en/pharmacology/classes/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](https://www.nhs.uk/medicines/gliclazide/) (NHS, 2026); [ATCDDD - ATC/DDD Index](https://atcddd.fhi.no/atc_ddd_index/?code=A10BB09) (WHO Collaborating Centre for Drug Statistics Methodology, 2026); [eEML - Electronic Essential Medicines List](https://list.essentialmeds.org/) (World Health Organization, 2025).

## **Spotted a mistake?** We are always improving for the community. Tell us what is wrong and our team will review it. Report a mistake

Representative model, for educational purposes only.

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License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/pharmacology/gliclazide/