Wockhardt wins FDA approval for Zaynich (cefepime and zidebactam), a novel intravenous antibiotic targeting drug-resistant Gram-negative bacteria in adults with complicated urinary tract infections (cUTI), including pyelonephritis. The approval carries a notable historical footnote: Zaynich is the first new chemical entity fully discovered and commercialized by an Indian pharmaceutical company to receive US FDA clearance.
Zaynich is indicated for cUTI caused by susceptible Gram-negative pathogens, including Escherichia coli, Klebsiella pneumoniae, Proteus mirabilis, Enterobacter cloacae complex, and Pseudomonas aeruginosa. It is administered intravenously and received Priority Review, Fast Track, and Qualified Infectious Disease Product designations from the FDA — the latter providing incentives designed to accelerate development of antibiotics against serious or life-threatening infections. The drug was also approved by India’s Drugs Controller General on May 27, 2026, and Wockhardt has submitted a marketing authorization application to the European Medicines Agency.
The approval rests primarily on results from ENHANCE-1, a Phase III randomized, double-blind, multicenter study enrolling 530 hospitalized adults with cUTI or acute pyelonephritis across 64 sites in the US, Europe, Latin America, China, and India. The trial compared Zaynich against meropenem, a carbapenem that represents a standard-of-care benchmark in serious Gram-negative infections. At the composite primary endpoint of clinical cure and microbiological response at the test-of-cure visit, Zaynich achieved a rate of 89.0% versus 68.4% for meropenem — a treatment difference of 20.6 percentage points (95% CI: 12.3, 29.5). The drug was described as generally well tolerated, with the most common adverse reactions — diarrhea, hypertension, headache, and hypokalemia — each occurring in at least 2% of patients.
What distinguishes Zaynich mechanistically from most beta-lactam/beta-lactamase inhibitor combinations is its multi-target engagement of penicillin-binding proteins. Cefepime, a fourth-generation cephalosporin, primarily inhibits PBP1a/b and PBP3, while zidebactam — a non-beta-lactam compound — selectively targets PBP2. By simultaneously engaging multiple PBPs across clinically important Gram-negative species, the combination achieves bactericidal activity even against organisms expressing diverse resistance mechanisms, including metallo-beta-lactamases not inhibited by zidebactam, hyper-efflux pumps, and downregulated outer membrane porins. This mechanistic breadth is the core rationale for its development against multidrug-resistant pathogens for which existing options are limited.
The approval places Zaynich in a competitive but still relatively sparse antibiotic landscape for cUTI. Cefiderocol (Fetroja, Shionogi), a siderophore cephalosporin approved in 2019, targets a similar MDR Gram-negative population including P. aeruginosa, using a distinct iron-uptake hijacking mechanism to penetrate bacterial outer membranes. Cefepime/enmetazobactam (Exblifep, Allecra Therapeutics), approved in 2024, shares the same cefepime backbone but pairs it with an extended-spectrum beta-lactamase inhibitor rather than a PBP2-targeting agent, giving it a different resistance-coverage profile. Zaynich’s superiority data against meropenem — rather than non-inferiority, which underpinned both comparators’ pivotal trials — may inform how clinicians position it, though cross-trial comparisons carry inherent limitations.