Pediatric Amoxicillin Compounding: Dose, BUD, and Label
A 4-year-old child weighing 16 kg presents with acute otitis media. The prescriber orders amoxicillin 90 mg/kg/day divided every 12 hours for 10 days. The pharmacy cannot obtain the commercial 250 mg/5 mL suspension. A pharmacist compounds an oral suspension from 250 mg amoxicillin capsules, purified water, and a flavored suspending agent. The label says 250 mg/5 mL, 150 mL, 'take 12.5 mL by mouth twice daily,' and a beyond-use date of 30 days at room temperature. The calculation worksheet shows 16 kg × 90 mg/kg/day = 1440 mg/day; 1440 ÷ 2 = 720 mg per dose; 720 ÷ 50 mg/mL = 14.4 mL per dose. The prescription says 12.5 mL. No stability study exists for this formulation, and the pharmacy uses USP <795> default BUDs when no stability data are available. The child has no allergies. The pharmacist is about to verify the label.
1. Evaluate the dose and the label directions. What should the pharmacist do before dispensing?
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The prescribed volume and the prescriber's mg/kg instruction do not match. At 250 mg/5 mL, 12.5 mL contains 625 mg per dose, or 1250 mg/day, which is about 78 mg/kg/day, not the 90 mg/kg/day stated in the order. The worksheet calculation of 14.4 mL would provide 720 mg per dose, or 1440 mg/day, which matches the stated mg/kg dose but not the written volume. The pharmacist must not silently choose one number. The prescriber should be contacted to clarify whether the intended dose is 12.5 mL twice daily or 14.4 mL twice daily, and the clarification should be documented on the prescription record. Only after clarification should the label be verified. If the prescriber cannot be reached, the pharmacist should not dispense an ambiguous pediatric antibiotic order. The pharmacist should also confirm the concentration and the total volume are sufficient for a 10-day course at the clarified dose.
2. Is the 30-day room-temperature beyond-use date appropriate? Explain the reasoning.
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Probably not. This is a water-containing oral compounded preparation, and the pharmacy has no formulation-specific stability study. Under USP <795> default limits, a water-containing oral preparation without stability data is generally assigned a beyond-use date of no more than 14 days when refrigerated. A 30-day room-temperature BUD is longer than the default allows and is not supported by the available evidence. The pharmacist should assign the conservative default BUD unless the pharmacy has documented stability data for this exact formulation and packaging. The label should state the actual BUD and the storage condition, and the compounding record should show the basis for the BUD. Because this is a pediatric antibiotic, the pharmacist should also counsel the caregiver to refrigerate the product, shake it well, measure with an oral syringe, and discard any remaining suspension after the BUD or after the course is completed.
3. What compounding and counseling documentation should accompany this prescription?
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The compounding record should identify the patient, prescriber, drug, strength, final quantity, all ingredients and lot numbers, the source capsules, the suspending agent, the water, the compounding date and time, the assigned BUD and storage condition, and the identity of the pharmacist who performed and verified the preparation. It should also include the dose calculation and the prescriber clarification. The label must include the patient name, drug name and concentration, directions, quantity, BUD, storage instructions, pharmacy information, and a warning to shake well.
Counseling should cover the exact dose in mL, use of an oral dosing syringe rather than a household spoon, refrigeration if required, shaking, completion of the 10-day course, and what to do about missed doses. The caregiver should be told to watch for rash, diarrhea, vomiting, or difficulty breathing and to contact the prescriber if these occur. Because the child is 4 years old, the pharmacist should confirm the caregiver can measure and administer the dose and should offer teach-back.