About This Calculator

This guide provides supporting information for the Plazomicin Dose Calculator. Plazomicin (ZEMDRI®) is an aminoglycoside antibiotic indicated for the treatment of complicated urinary tract infections (cUTI), including pyelonephritis. Dosing is critically dependent on a patient’s renal function, which is estimated using creatinine clearance (CrCl). This information is intended for healthcare professionals and should not replace clinical judgment or official prescribing information.

Outputs Explained

After entering the required patient data, the calculator provides the following key outputs:

• Recommended Dose: The final calculated dose in milligrams (mg), rounded to the nearest whole number.
• Dosing Regimen: The corresponding administration schedule based on the patient’s CrCl category (e.g., 15 mg/kg every 24 hours).
• Creatinine Clearance (CrCl): The estimated renal function in mL/min, calculated using the Cockcroft-Gault equation.
• Dosing Weight Used: The weight in kilograms (kg) used for the dose calculation. This will be the patient’s Actual, Ideal, or Adjusted Body Weight, depending on their obesity status.

How to Use the Calculator

To ensure an accurate dose calculation, please provide the following patient parameters:

• Age: Patient’s age in years (must be 18 or older).
• Sex: Biological sex, as it is a variable in the Cockcroft-Gault and Ideal Body Weight formulas.
• Height: Patient’s height, used to calculate Ideal Body Weight (IBW). Can be entered in centimeters or inches.
• Actual Body Weight: The patient’s current measured weight. Can be entered in kilograms or pounds.
• Serum Creatinine (SCr): The most recent serum creatinine value, a key marker of kidney function. Can be entered in mg/dL or μmol/L.

Dosing Overview

Plazomicin dosing is stratified by renal function. The calculator implements the following FDA-approved dosing schedules for cUTI:

• CrCl ≥ 60 mL/min: 15 mg/kg administered every 24 hours.
• CrCl 30 to 59 mL/min: 10 mg/kg administered every 24 hours.
• CrCl 15 to 29 mL/min: 7.5 mg/kg administered every 48 hours.
• CrCl < 15 mL/min: Plazomicin is not recommended for patients with a CrCl below 15 mL/min, including those on hemodialysis, as its pharmacokinetics have not been established in this population.

Switching Therapy

When switching from another antibacterial agent to Plazomicin, or vice-versa, consider the pharmacokinetic and pharmacodynamic properties of both drugs. The timing of the first Plazomicin dose should be based on the dosing interval of the previous antibiotic. Always exercise clinical judgment and consult the full prescribing information for guidance on therapeutic transitions.

Missed Dose Protocol

If a dose of Plazomicin is missed, it should be administered as soon as possible. If it is almost time for the next scheduled dose, the missed dose should be skipped, and the regular dosing schedule should be resumed. Do not administer a double dose to make up for a missed one. Patients should be advised to contact their healthcare provider for instructions.

Safety Alerts

Plazomicin carries FDA Black Box Warnings for several serious adverse reactions common to the aminoglycoside class. Healthcare providers must monitor patients closely.

• Nephrotoxicity: Potential for kidney damage. Monitor renal function (e.g., SCr, BUN) daily during therapy.
• Ototoxicity: Can cause irreversible hearing loss, dizziness, or tinnitus. Monitor for auditory and vestibular changes.
• Embryo-Fetal Toxicity: May cause fetal harm. Assess pregnancy status before initiation.
• Neuromuscular Blockade: Can cause or worsen muscle weakness and lead to respiratory paralysis, particularly in patients with myasthenia gravis or those receiving neuromuscular blocking agents.

Frequently Asked Questions

What formula is used to calculate creatinine clearance?

The calculator uses the Cockcroft-Gault equation, which is the method specified in the Plazomicin prescribing information for dose adjustments.

Why does the calculator sometimes use ‘Adjusted Body Weight’?

For obese patients (Actual Body Weight >120% of Ideal Body Weight), using adjusted body weight for dosing can prevent potential overdose and toxicity. The calculator automatically determines and applies the appropriate weight (Actual, Adjusted, or Ideal) based on standard clinical formulas.

Is this calculator suitable for pediatric patients?

No. The safety and effectiveness of Plazomicin have not been established in patients under 18 years of age. This calculator is only validated for adults.

What is the maximum recommended dose?

While the calculator provides a dose based on weight, clinical judgment is always necessary. The prescribing information does not specify an absolute maximum dose, but doses should always be based on the mg/kg recommendations for the patient’s renal function category.

How is Ideal Body Weight (IBW) calculated?

The calculator uses the Devine formula for IBW: 50 kg + 2.3 kg for each inch over 5 feet for males, and 45.5 kg + 2.3 kg for each inch over 5 feet for females.

Can Plazomicin be used in patients on dialysis?

No, the use of Plazomicin is not recommended in patients with CrCl < 15 mL/min, which includes patients requiring hemodialysis.

How often should renal function be monitored?

Renal function should be monitored daily during Plazomicin therapy to allow for prompt dose adjustments if the patient’s CrCl changes significantly.

What is the indication for Plazomicin?

Plazomicin is indicated for the treatment of patients 18 years of age or older with complicated Urinary Tract Infections (cUTI), including pyelonephritis, caused by designated susceptible microorganisms.

References

• [1] ZEMDRI® (plazomicin) [Prescribing Information]. Cipla USA, Inc. Warren, NJ. Available at: FDA.gov
• [2] U.S. Food and Drug Administration. Drugs@FDA: FDA-Approved Drugs. ZEMDRI (plazomicin) injection. Application No. 209394. Available at: accessdata.fda.gov
• [3] Connolly LE, Riddle V, Panga J, et al. A Multicenter, Randomized, Double-blind, Phase 2 Study of the Efficacy and Safety of Plazomicin Compared with Levofloxacin for the Treatment of Complicated Urinary Tract Infection and Acute Pyelonephritis. Antimicrob Agents Chemother. 2018;62(5):e02257-17. Available at: ncbi.nlm.nih.gov
• [4] Cipla USA. ZEMDRI® (plazomicin) for injection. Official Product Website. Available at: ciplausa.com