Duration of Action of Solostar (Insulin Glargine)
Insulin glargine (Solostar) has a duration of action of approximately 24 hours, with an onset of approximately 1 hour and no pronounced peak, making it suitable for once-daily basal insulin coverage. 1
Pharmacodynamic Profile
The FDA label clearly establishes that insulin glargine demonstrates a median duration of 24 hours (range: 10.8 to >24 hours) after subcutaneous injection, compared to NPH insulin which has a median duration of only 14.5 hours (range: 9.5 to 19.3 hours). 1
Key pharmacokinetic characteristics include:
- Onset of action: Approximately 1 hour after subcutaneous injection 2, 1
- Peak action: No pronounced peak—provides a relatively constant, peakless insulin concentration profile over 24 hours 2, 1
- Duration: Up to 24 hours of glucose-lowering effect 3, 2
Clinical Implications of the 24-Hour Duration
The extended duration profile offers several practical advantages:
- Once-daily dosing: The 24-hour duration allows administration at any consistent time of day (morning, bedtime, or other convenient time), though consistency is recommended 3, 2
- Stable basal coverage: Insulin glargine slowly releases over 24 hours, creating more physiologic basal insulin levels that suppress hepatic glucose production between meals and overnight 4, 2
- Reduced hypoglycemia risk: The peakless profile significantly reduces nocturnal hypoglycemia compared to NPH insulin, which has a pronounced peak at 6-8 hours 4, 2
Important Caveats About Duration
In some patients, insulin glargine may not provide full 24-hour coverage, and twice-daily dosing should be considered when once-daily administration fails to maintain glycemic control throughout the day. 3
Specific situations requiring consideration of split dosing include:
- Patients with type 1 diabetes experiencing persistent glycemic variability despite optimal once-daily titration 3
- Individuals requiring high basal insulin doses that may exceed absorption capacity for single-injection administration 3
- Patients with refractory hypoglycemia or inadequate fasting/pre-dinner glucose control 3
The American Diabetes Association explicitly recognizes that basal insulins including glargine may require twice-daily dosing when once-daily fails to provide adequate 24-hour coverage. 3
Comparison with Other Insulin Types
| Insulin Type | Onset | Peak | Duration |
|---|---|---|---|
| Rapid-acting (lispro, aspart) | 5 minutes | 1-2 hours | 3-4 hours |
| Regular insulin | 15 minutes | 3-4 hours | 6-8 hours |
| NPH (intermediate-acting) | 1 hour | 6-8 hours | 12 hours |
| Glargine (Solostar) | 1 hour | None | 24 hours |
Site of Administration
The duration of action remains similar regardless of injection site—abdominal, deltoid, or thigh subcutaneous administration all provide comparable 24-hour coverage. 1