FDA Approves Zinplava for Preventing Return of C diff

October 24, 2016

The US Food and Drug Administration (FDA) has approved bezlotoxumab injection (Zinplava, Merck) to reduce the recurrence of Clostridium difficile infection (CDI) in patients aged 18 years or older, the manufacturer announced last Friday.

The human monoclonal antibody is specifically indicated for adults who are taking an antibiotic for CDI and are at risk of becoming infected again. Not an antibiotic itself, bezlotoxumab binds to — and neutralizes — toxin B, one of several toxins produced by C difficile and the one considered central to the life-threatening virulence of the bacteria. Bezlotoxumab is administered intravenously (IV) as a single dose of 10 mg/kg over 1 hour.

The Centers for Disease Control and Prevention estimated that CDI caused almost 500,000 illnesses and 29,000 deaths within 1 month of the initial diagnosis in 2011. CDI recurs in roughly 20% of people who have had the infection. Patients taking antibiotics are 7 to 10 times more likely to contract CDI. The overprescribing of antibiotics has combined with poor hygiene and infection control on the part of healthcare workers to make CDI a scourge in the nation's hospitals and nursing homes.

In June, the FDA's Antimicrobial Drugs Advisory Committee voted 10 to 5 — with 1 abstention — to recommend approval of bezlotoxumab, primarily on the basis of two phase 3 trials that were randomized, multicenter, double-blinded, and placebo-controlled. Nausea, fatigue, fever, and headache were among the most common adverse events experienced on the day of infusion, or the day after, according to Merck. They also made the list of the most common adverse events within 4 weeks of infusion. Twelve weeks out, heart failure emerged as a serious adverse reaction.

"These adverse reactions occurred primarily in patients with underlying congestive heart failure," said Merck in regard to heart failure. Consequently, the company cautioned that when patients have a history of congestive heart failure, bezlotoxumab "should be reserved for use when the benefit outweighs the risk."

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