Final answer:
To determine the pediatric dose of ampicillin for a 48 lb child, we scale the adult dose based on the child's weight and then calculate the volume needed per dose using the concentration of the oral suspension. The child should receive 3.1 mL of the ampicillin oral suspension per dose.
Step-by-step explanation:
Calculating the dose of ampicillin for a 48 lb child requires the use of pediatric dosing principles. The adult dose is 1,500 mg daily, given tid (three times a day) in equally divided doses. Since the dose for children is often based on body weight, typically in milligrams per kilogram, we must first convert the child's weight from pounds to kilograms. In this case, 48 lbs is approximately 21.77 kg (1 kg = 2.2 lbs).
It's common to use a fraction of the adult dose based on the child's weight or to use a pediatric dosing chart. If we assume a straight weight-based scaling, and the child gets a dose proportional to their weight compared to an adult's average weight (let's use 70 kg as an average adult weight), the dose for the child would be:
Child Dose (mg) = Adult Dose (mg) x (Child Weight (kg) / Adult Weight (kg))
Therefore, the child dose would be approximately:
Child Dose (mg) = 1,500 mg x (21.77 kg / 70 kg) = ~466 mg/day
Since the medication is to be given tid, we divide the total daily dose by three to find each dose:
Dose per administration = 466 mg/day ÷ 3 = ~155 mg/dose
Next, we need to calculate the volume of suspension to administer per dose. Since we have an oral suspension of 250 mg in 5 mL, we use the following calculation:
Volume per dose (mL) = (Dose (mg) ÷ Volume of suspension (mL)) / Concentration of suspension (mg)
This gives us:
Volume per dose (mL) = (155 mg ÷ 5 mL) / 250 mg = 3.1 mL
The child should receive 3.1 mL of the oral suspension per dose.