A child who weighs 10 kg will begin taking oral trimethoprim-sulfamethoxazole (TMP-SMX). The liquid preparation contains 40 mg of TMP and 200 mg of SMX per 5 mL. The nurse determines that the child's dose should be 8 mg of TMP and 40 mg of SMX/kg/day divided into two doses. Which order for this child is correct?
Correct Answer: A
Rationale: The correct answer is A: '5 mL PO BID.' To calculate the child's daily dose requirement, you multiply the child's weight (10 kg) by the prescribed dosage per kg, which is 8 mg for TMP and 40 mg for SMX. This results in a total daily requirement of 80 mg of TMP and 400 mg of SMX. To divide this into two doses, each dose should contain half of the total daily requirement, which is 40 mg TMP and 200 mg SMX. Since the liquid preparation contains 40 mg of TMP and 200 mg of SMX per 5 mL, the correct dose per administration is 5 mL. Therefore, 5 mL PO BID is the correct order. Choice B, '5 mL PO daily,' is incorrect as the total daily dose needs to be divided into two doses. Choices C and D, '10 mL PO BID' and '10 mL PO daily,' respectively, are incorrect as they do not align with the calculated dosage requirements based on the child's weight and the prescribed dosage per kg.