What is the recommended dosage of Piptaz (Piperacillin/Tazobactam) for a 40kg child?

Piperacillin-Tazobactam Dosing for a 40 kg Child

For a 40 kg child, administer piperacillin-tazobactam 3200 mg/400 mg (based on piperacillin component) intravenously every 6 hours for serious infections, or 2400 mg/300 mg every 6 hours for less severe infections.

Weight-Based Dosing Approach

Since this child weighs 40 kg, they fall into a transitional zone where pediatric dosing guidelines converge with adult dosing considerations:

• For complicated intra-abdominal infections and serious infections: The recommended pediatric dose is 200-300 mg/kg/day of the piperacillin component divided every 6-8 hours 1
• At 40 kg body weight: This translates to 80-100 mg/kg per dose every 6 hours, which equals 3200-4000 mg per dose 1
• Standard pediatric dosing: 80-100 mg/kg every 8 hours has been validated in infants and children, with the higher end (100 mg/kg) recommended for serious infections 2, 3

Specific Dosing Recommendations by Infection Severity

For Serious/Complicated Infections

• Dose: 100 mg/kg (piperacillin component) = 4000 mg every 6 hours 1
• This achieves optimal pharmacodynamic targets with free piperacillin concentrations above the MIC for >75% of the dosing interval 2
• Maximum single dose should not exceed the adult dose of 4000 mg piperacillin 1

For Moderate Infections

• Dose: 80 mg/kg (piperacillin component) = 3200 mg every 6 hours 1
• This provides adequate coverage for most susceptible organisms 3

For Multidrug-Resistant Organisms

• Dose: 200-300 mg/kg/day divided every 6-8 hours 1
• At 40 kg, this equals 2000-3000 mg per dose every 6 hours (maximum 12,000 mg/day) 1

Dosing Interval Considerations

Every 6 hours is preferred over every 8 hours for this weight category when treating serious infections 1. The pharmacokinetic data demonstrate that:

• Piperacillin elimination half-life in children is approximately 0.8-1.0 hours 3
• More frequent dosing (Q6H) maintains therapeutic concentrations above the MIC for a greater proportion of the dosing interval 2
• The fixed 8:1 ratio of piperacillin to tazobactam should be maintained 3

Practical Administration

• Infusion time: Administer as a 30-minute intravenous infusion 1
• Preparation: Each dose of 3200 mg piperacillin contains 400 mg tazobactam (8:1 fixed ratio) 3
• Renal adjustment: No dose adjustment needed if renal function is normal 1

Important Clinical Caveats

Children weighing >40 kg can be dosed as adults according to multiple guidelines 1. However, at exactly 40 kg, using weight-based pediatric dosing (80-100 mg/kg) is more precise than defaulting to standard adult dosing of 3.375 g or 4.5 g every 6-8 hours.

Monitor for nephrotoxicity with prolonged therapy, as elevated piperacillin exposure has been associated with renal toxicity 4. However, the dosing regimens recommended here are within established safe ranges 2, 3.

Duration of therapy should be individualized based on infection site, source control, and clinical response, typically 7-14 days for complicated infections 1.