What is the maximum daily dosing of Gliclazide (a sulfonylurea) for a patient with type 2 diabetes and potentially impaired renal function?

Maximum Gliclazide 80 mg Dosing

The maximum daily dose of gliclazide immediate release (80 mg formulation) is 320 mg per day, typically administered in divided doses. 1, 2

Standard Dosing Parameters

• Gliclazide immediate release 80 mg can be dosed up to 320 mg daily, which represents the maximum therapeutic dose studied in clinical trials 2
• When doses exceed 80 mg daily, the medication should be administered in divided doses (typically twice daily) rather than as a single dose 1
• The typical twice-daily regimen involves dosing in the morning and evening 1

Dosing Adjustments for Special Populations

Patients with Renal Impairment

• Gliclazide demonstrates a very good safety profile in patients with impaired renal function, as renal clearance accounts for only 4% of total drug clearance 3, 4
• The drug is extensively metabolized rather than renally excreted, making it safer than many other sulfonylureas in renal impairment 4
• No specific dose reduction is required for renal impairment based on the pharmacokinetic profile, though clinical monitoring remains important 3, 4

Elderly Patients

• Gliclazide maintains efficacy and safety in elderly patients without requiring dose adjustments 3
• The incidence of hypoglycemia remains similarly low in elderly patients compared to younger populations 3

Practical Dosing Strategy

When uptitrating gliclazide 80 mg:

• Start with 80 mg once or twice daily depending on glycemic control needs 1
• For twice-daily dosing, administer the full dose in the morning and evening (e.g., 80 mg twice daily = 160 mg total) 1
• Maximum dose is 320 mg daily (e.g., 160 mg twice daily or divided into multiple doses) 2
• If glycemic targets are not achieved at 160 mg/day, consider adding another agent rather than uptitrating to maximum dose, as combination therapy shows superior efficacy 2

Important Clinical Considerations

Hypoglycemia Risk

• The incidence of symptomatic hypoglycemia with gliclazide is low at approximately 4.8 episodes per 100 patient-years, with no severe episodes requiring third-party assistance in major trials 3, 5
• Gliclazide's intermediate half-life of 11 hours and specific effect on first-phase insulin release contribute to lower hypoglycemia rates compared to other sulfonylureas 4

Alternative to Maximum Dose Uptitration

• Adding rosiglitazone 4 mg twice daily to gliclazide 160 mg/day is significantly more effective than uptitrating gliclazide to 320 mg/day, reducing HbA1c by an additional 1.3% 2
• Consider combination therapy when half-maximal doses (160 mg/day) fail to achieve glycemic targets rather than pushing to maximum sulfonylurea doses 2

Common Pitfalls to Avoid

• Avoid assuming all sulfonylureas require dose reduction in renal impairment—gliclazide's predominantly hepatic metabolism makes it safer in this population 4
• Do not administer doses >80 mg as a single daily dose with the immediate release formulation; use divided dosing 1
• Consider alternative therapeutic options with lower hypoglycemia risk (such as SGLT2 inhibitors or GLP-1 receptor agonists) in high-risk patients before maximizing sulfonylurea doses 6