Dispense a 15 mL supply (three 3 mL pens) for a 30-day supply of Lantus SoloStar at 12 units nightly.
Volume Calculation
For a patient taking 12 units nightly of Lantus SoloStar 100 units/mL:
- Daily dose: 12 units = 0.12 mL (since 100 units/mL means 12 units ÷ 100 = 0.12 mL)
- 30-day supply: 12 units × 30 days = 360 units total = 3.6 mL total volume
Practical Dispensing Recommendation
Dispense five 3 mL Lantus SoloStar pens (the standard package configuration) 1. Each pen contains 3 mL (300 units), and the patient will use:
- Approximately 1.2 pens per month (360 units ÷ 300 units per pen)
- Each opened pen must be discarded after 28 days per FDA labeling 1
Critical Dispensing Considerations
The 28-day discard rule is paramount: Once a Lantus SoloStar pen is opened, it must be used within 28 days regardless of remaining insulin 1. This means:
- The patient will open pen #1 on day 1
- After 25 days (12 units × 25 days = 300 units), they'll finish pen #1
- They'll open pen #2 on day 26
- Pen #2 must be discarded on day 54 (28 days after opening), even with insulin remaining
For a true 30-day supply: Dispense two 3 mL pens initially, which provides adequate coverage accounting for the 28-day stability window.
For a 90-day supply: Dispense five 3 mL pens (the standard carton) 1, which accounts for waste from the 28-day discard requirement.
Device Accuracy
The SoloStar pen delivers highly accurate doses. Studies demonstrate 100% of doses fall within ISO accuracy standards, with mean delivered doses of 39.63 units for a 40-unit target 2, 3. This precision is superior to syringes, particularly at low doses 4, making pens the preferred delivery method per current guidelines 5.
Patient Education Points
Ensure the patient understands:
- Remove the inner needle cover before injection (a common error leading to dose failure) 6
- Hold pen perpendicular to skin (90° angle) with 4-5mm needles 6
- Press dose button completely and wait 10 seconds before removing needle to prevent insulin leakage 6
- Rotate injection sites systematically to prevent lipodystrophy 6