Should the dose of piperacillin (Pip/Taz) (piperacillin-tazobactam) be calculated based on ideal body weight in children with pneumonia, such as a 6-year-old weighing 26 kg?

Piperacillin-Tazobactam Dosing in Children with Pneumonia

For a 6-year-old child weighing 26 kg with pneumonia, piperacillin-tazobactam should be dosed based on actual body weight at 112.5 mg/kg (100 mg piperacillin and 12.5 mg tazobactam) every 6 hours, not ideal body weight.

Dosing Recommendations Based on FDA Guidelines

The FDA-approved dosing for piperacillin-tazobactam in pediatric patients with nosocomial pneumonia is clearly specified based on age and actual body weight 1:

• For children older than 9 months: 112.5 mg/kg (100 mg piperacillin and 12.5 mg tazobactam) every 6 hours
• For children 2-9 months: 90 mg/kg (80 mg piperacillin and 10 mg tazobactam) every 6 hours

For a 6-year-old child weighing 26 kg with pneumonia, the appropriate dose would be:

• 112.5 mg/kg × 26 kg = 2,925 mg (approximately 3 grams) per dose every 6 hours

Administration Considerations

• Administer by intravenous infusion over 30 minutes 1
• The drug should be reconstituted and diluted according to the specific instructions in the FDA label
• For pediatric patients weighing up to 40 kg, the reconstituted solution should be further diluted to a final piperacillin concentration between 20-80 mg/mL 1

Pharmacokinetic Considerations

Research supports the use of actual body weight for dosing in children:

• Pharmacokinetic studies in critically ill children have demonstrated that weight is significantly associated with piperacillin clearance 2
• The volume of distribution for piperacillin in children has been reported as 0.43 ± 0.16 L/kg, which is weight-dependent 2
• For children between 1-6 years of age, the mean clearance of piperacillin is approximately 0.299 L/hr/kg 3

Pharmacodynamic Considerations

The FDA-approved dosing regimen is designed to achieve adequate pharmacodynamic targets:

• The bactericidal target for piperacillin-tazobactam is free drug concentration above the MIC for ≥50% of the dosing interval 3
• For susceptible bacterial pathogens, doses of ≥80/10 mg/kg given every 8 hours and infused over 4 hours achieve adequate pharmacodynamic exposures in critically ill children 2
• The recommended dose of 112.5 mg/kg every 6 hours provides appropriate coverage for most common pathogens causing pneumonia in children 1

Important Considerations

• No dose adjustment based on ideal body weight is mentioned in any of the guidelines or FDA labeling
• For children weighing over 40 kg, the adult dosing regimen should be used 1
• Dose adjustment is required for patients with renal impairment, though specific pediatric guidelines for renal adjustment are not well established 1

Monitoring

• Clinical improvement should be assessed within 48-72 hours
• Signs of improvement include decreased respiratory rate, reduced work of breathing, improved oxygen saturation, decreased fever, and improved feeding
• Consider reviewing therapy if no improvement is seen within 48 hours

In conclusion, for the 6-year-old child weighing 26 kg with pneumonia, the appropriate piperacillin-tazobactam dosing should be based on actual body weight, not ideal body weight, at 112.5 mg/kg every 6 hours.