General Information

Zemdri (plazomicin) is an aminoglycoside antibacterial.

Zemdri is specifically indicated in patients 18 years of age or older for the treatment of complicated urinary tract infections (cUTI), including pyelonephritis caused by the following susceptible microorganism(s): Escherichia coli, Klebsiella pneumoniae, Proteus mirabilis, and Enterobacter cloacae. 

Zemdri is supplied as a solution for intravenous infusion. To reduce the development of drug-resistant bacteria and maintain the effectiveness of Zemdri and other antibacterial drugs, Zemdri should be used only to treat or prevent infections that are proven or strongly suspected to be caused by susceptible bacteria. The recommended dosage regimen of Zemdri is 15 mg/kg administered every 24 hours by intravenous (IV) infusion over 30 minutes in patients 18 years of age or older and with creatinine clearance (CLcr) greater than or equal to 90 mL/min. The duration of therapy should be guided by the severity of infection and the patient’s clinical status for up to 7 days. During treatment, dosage adjustments may be required based on change in renal function.

Mechanism of Action

Zemdri (plazomicin) is an aminoglycoside antibacterial. It acts by binding to bacterial 30S ribosomal subunit, thereby inhibiting protein synthesis. Plazomicin has concentration-dependent bactericidal activity as measured by time kill studies. In vitro studies demonstrated a plazomicin post-antibiotic effect ranging from 0.2 to 2.6 hours at 2X MIC against Enterobacteriaceae. 

Side Effects

Adverse effects associated with the use of Zemdri may include, but are not limited to, the following:

• decreased renal function
• diarrhea
• hypertension
• headache
• nausea
• vomiting
• hypotension

The Zemdri drug label comes with the following Black Box Warning: Nephrotoxicity has been reported with Zemdri. The risk of nephrotoxicity is greater in patients with impaired renal function, the elderly, and in those receiving concomitant nephrotoxic medications. Ototoxicity, manifested as hearing loss, tinnitus, and/or vertigo, has been reported with Zemdri. Symptoms of aminoglycoside associated ototoxicity may be irreversible and may not become evident until after completion of therapy. Aminoglycosides have been associated with neuromuscular blockade. During therapy with Zemdri, monitor for adverse reactions associated with neuromuscular blockade particularly in high-risk patients. Aminoglycosides, including Zemdrican cause fetal harm when administered to a pregnant woman. 

Clinical Trial Results

The FDA approval of Zemdri was based on a randomized, multinational, double-blind, noninferiority trial in a total of 609 adults hospitalized with cUTI (including pyelonephritis). The trial compared Zemdri (15 mg/kg IV once daily as a 30-minute infusion) to meropenem (1 g intravenously every 8 hours as a 30-minute infusion). Switch to an oral antibacterial drug, such as levofloxacin, was allowed after a minimum of 4 and maximum of 7 days of IV therapy for a total of 7 to 10 days of treatment. Efficacy was assessed in the microbiological modified intent-to-treat (mMITT) population, which included all patients who received study medication and had at least 1 baseline uropathogen. The mMITT population excluded patients with organisms resistant to study drugs. Zemdri demonstrated non-inferiority to meropenem for the co-primary efficacy endpoints of composite cure (clinical cure and microbiological eradication) in the microbiological modified intent-to-treat (mMITT; N=388) population at Day 5 and test-of-cure (TOC) visit (Day 17 + 2). Composite cure rates at Day 5 were 88.0% (168/191) for Zemdri vs 91.4% (180/197) for meropenem. Composite cure rates at TOC were 81.7% (156/191) for Zemdri vs 70.1% (138/197) for meropenem. Composite cure at the TOC visit in patients with concomitant bacteremia at baseline was achieved in 72.0% (18/25) of patients in the Zemdri group and 56.5% (13/23) of patients in the meropenem group.