What is the appropriate dosing regimen for gliclazide (sulfonylurea) when not using the modified release formulation?

Gliclazide Immediate-Release Dosing Regimen

For immediate-release (non-modified release) gliclazide, doses up to 80 mg should be given once daily at breakfast, while doses exceeding 80 mg should be divided into twice-daily administration (BD), with a maximum total daily dose of 320 mg. 1

Dosing Algorithm

Initial Dosing

• Start with 40-80 mg once daily at breakfast for most patients 1
• For patients with renal impairment (eGFR 30-50 mL/min/1.73 m²), initiate conservatively at lower end of range due to hypoglycemia risk 2

Dose Escalation Strategy

• If total daily dose ≤80 mg: Administer as single morning dose (OD) 1
• If total daily dose >80 mg: Split into twice-daily dosing (BD) - typically before breakfast and dinner 1
• Maximum dose: 320 mg daily (divided doses if >80 mg) 1

Titration Timeline

Based on real-world evidence, progressive uptitration shows:

• 15% reach optimal dose by month 1
• 39% by month 2
• 59% by month 3
• 92% by month 6 3

Key Clinical Considerations

Why the 80 mg Threshold Matters

The immediate-release formulation lacks the hydrophilic matrix technology of modified-release gliclazide, resulting in less consistent 24-hour coverage 4. Dividing doses >80 mg provides better glycemic control throughout the day and reduces hypoglycemia risk by avoiding excessive peak concentrations 5.

Common Pitfall to Avoid

Do not continue escalating gliclazide beyond 15-20 mg daily if glycemic targets are not met - further dose increases rarely provide meaningful benefit and increase hypoglycemia risk. Instead, consider switching to insulin or adding agents with cardiovascular/renal benefits (SGLT2 inhibitors or GLP-1 receptor agonists) 2.

Renal Function Assessment

• eGFR >50 mL/min/1.73 m²: No dose adjustment needed 2
• eGFR 30-50 mL/min/1.73 m²: Use conservative dosing, titrate slowly 2
• eGFR <30 mL/min/1.73 m²: Consider alternative agents 2

Special Population: Ramadan Fasting

For Muslim patients observing Ramadan with twice-daily dosing, take half the usual morning dose at predawn meal and full dose at sunset meal 6, 1