Pediatric Dose Calculation and Preparation Verification
A prescriber orders gentamicin 5 mg/kg/day divided every 8 hours for a 12 kg pediatric patient with a severe infection. The pharmacy has gentamicin 40 mg/mL vials and 0.9% sodium chloride bags. The order is to infuse each dose over 30 minutes. The technician calculates the dose as 20 mg per dose and plans to withdraw 0.5 mL of the 40 mg/mL vial into a 50 mL bag. The pharmacist notices the calculation and asks the technician to verify the dose and the preparation. The patient's renal function is normal, and the order is for 7 days.
1. Verify the dose calculation and identify any error.
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Calculation:
- 5 mg/kg/day × 12 kg = 60 mg/day.
- Divided every 8 hours = 3 doses/day → 60 mg ÷ 3 = 20 mg per dose.
Volume: 20 mg ÷ 40 mg/mL = 0.5 mL.
The technician's dose and volume are correct. However, the preparation must be verified for:
- Concentration and final volume: 20 mg in a 50 mL bag is a reasonable dilution for a 30-minute infusion.
- Stability: Gentamicin is stable in 0.9% sodium chloride; confirm the BUD.
- Labeling: Include dose, rate, and patient-specific information.
Model answer: The dose is 20 mg per dose (0.5 mL of 40 mg/mL), which is correct; verify dilution, stability, and labeling before release.
2. What additional verification steps should the pharmacist perform before releasing this pediatric CSP?
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Additional verification:
- Weight-based double check: Confirm the patient's weight (12 kg) and that the order is per day, not per dose.
- Renal function: Normal renal function supports the every-8-hour interval; document the assessment.
- Concentration check: Confirm the final concentration is appropriate for pediatric administration and that the infusion rate (30 minutes) is safe.
- Compatibility: Verify gentamicin compatibility with 0.9% sodium chloride and any other concurrent medications.
- Labeling: Include the patient's name, dose, volume, rate, and BUD.
- Documentation: Record the calculation, the verifier's signature, and the time of preparation.
Model answer: Double-check the weight-based dose, renal function, concentration, compatibility, labeling, and documentation before release.