A patient is using Lantus (insulin glargine) 25 units twice daily via pen; how many pens should be ordered for a 30‑day supply?

Lantus Pen Supply Calculation for 30 Days

Order 2 Lantus SoloStar pens for a 30-day supply when the patient is using 25 units twice daily (50 units total per day).

Calculation Breakdown

The patient requires:

• 25 units twice daily = 50 units per day
• 30 days × 50 units/day = 1,500 units total

Each Lantus SoloStar pen contains 300 units 1:

• 1,500 units ÷ 300 units per pen = 5 pens needed

However, this is not the standard dosing for Lantus. Lantus is FDA-approved and designed for once-daily administration, not twice daily 1.

Critical Prescribing Issue

The current regimen (25 units twice daily) is off-label and potentially problematic. The FDA label explicitly states that "LANTUS should be administered subcutaneously once a day at the same time every day" 1. Lantus exhibits a relatively constant glucose-lowering profile over 24 hours that permits once-daily dosing 1.

Recommended Action

Before ordering pens, contact the prescriber to clarify the intended regimen:

1. If truly twice-daily dosing is intended (uncommon but occasionally used in specific clinical situations 2, 3):

   • Order 5 Lantus SoloStar pens for 30 days
   • Document the off-label use
   • Consider whether the patient might benefit from switching to once-daily dosing at 50 units

2. If once-daily dosing was intended (standard practice):

   • The patient should receive 50 units once daily
   • Order 5 Lantus SoloStar pens for 30 days (same calculation: 1,500 units ÷ 300 units/pen)

3. If the prescription error meant 25 units once daily:

   • Order 3 Lantus SoloStar pens for 30 days (750 units ÷ 300 units/pen)

Common Pitfalls to Avoid

• Never assume twice-daily Lantus is standard: While some research suggests twice-daily glargine may reduce predose hyperglycemia in specific populations 3, once-daily dosing remains the FDA-approved and guideline-recommended approach 1
• Account for pen wastage: Patients may not extract every unit from a pen, so ordering one extra pen for a 90-day supply is prudent
• Verify the formulation: Lantus comes in both vials and SoloStar pens; ensure the prescription specifies pens if that's what the patient uses 1
• Check for U-300 vs U-100: Standard Lantus is U-100; U-300 glargine (Toujeo) is a different product with different dosing 4, 5

Bottom line: Clarify the prescription with the provider before dispensing, as twice-daily Lantus dosing is unusual and may represent a prescribing error.