How many pens of Lantus (insulin glargine) should be dispensed for a 90-day supply for a patient taking 20 units daily?

Lantus Insulin Pen Dispensing for 90-Day Supply

For a patient taking Lantus (insulin glargine) 20 units daily, 3 pens should be dispensed for a 90-day supply.

Calculation of Insulin Pen Quantity

To determine the appropriate number of Lantus pens to dispense for a 90-day supply, we need to consider:

1. Daily insulin requirement
2. Total insulin needed for 90 days
3. Amount of insulin contained in each pen

Step-by-Step Calculation:

• Daily dose: 20 units of Lantus
• Duration: 90 days
• Total insulin required: 20 units × 90 days = 1,800 units
• Standard Lantus SoloStar prefilled pen contains 3 mL of insulin glargine at a concentration of 100 units/mL 1
• Total units per pen: 3 mL × 100 units/mL = 300 units
• Number of pens needed: 1,800 units ÷ 300 units per pen = 6 pens

However, the FDA label for insulin glargine indicates that each pen contains 3 mL of insulin glargine at a concentration of 100 units/mL, providing 300 units per pen 1. Therefore, the actual calculation is:

• Number of pens needed: 1,800 units ÷ 300 units per pen = 6 pens

Clinical Considerations

Insulin Administration Guidelines

• Insulin glargine is administered subcutaneously once daily at any time of day but should be given at the same time every day 1
• Injection sites should be rotated within the same region (abdomen, thigh, or deltoid) to reduce the risk of lipodystrophy 1
• The American Diabetes Association recommends monitoring blood glucose levels during insulin therapy, especially when making changes to the regimen 2

Storage and Handling

• Unopened insulin pens should be stored in the refrigerator (36°F to 46°F)
• Once in use, insulin pens can be kept at room temperature (below 86°F) for up to 28 days
• Insulin pens should never be shared between patients, even if the needle is changed 1

Patient Education Points

• Proper injection technique should be reviewed with the patient
• The patient should be educated on recognition and treatment of hypoglycemia 2
• The patient should be advised to always carry a source of quick-acting carbohydrates 2

Important Considerations for Dispensing

When dispensing Lantus insulin pens, it's important to consider:

1. Insurance coverage and quantity limitations
2. Potential need for additional pens to account for any wastage or dosage adjustments
3. Ensuring the patient has enough insulin until their next refill

By dispensing 6 pens for a 90-day supply, the patient will have exactly the amount needed for their prescribed daily dose of 20 units.