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Ciprofloxacin, often called Cipro, its original trade name, is one of the world’s most widely prescribed antibiotics for bacterial infections. It is a member of the quinoline antibacterial class and is a descendant of norfloxacin, the first quinoline antibiotic to contain a fluorine atom.
In the 1980s, scientists at Bayer Pharmaceuticals discovered that replacing the ethyl group of norfloxacin with a cyclopropyl group greatly increased its Gram-negative bactericidal activity. In 1987, Bayer received US Food and Drug Administration approval for orally administered ciprofloxacin; the intravenous form was approved in 1991.
Since Bayer’s patent expired in 2004, ciprofloxacin has been widely distributed as an inexpensive broad-spectrum antibacterial. It is on the World Health Organization's List of Essential Medicines.
MOTW update:
August 25, 2025
Ciprofloxacin1 is one of the world’s most widely prescribed antibiotics for bacterial infections.
Although bubonic plague has been largely eradicated, it still exists in some parts of the world. This month, Piero Olliaro at the University of Oxford (UK) and collaborators there and in Madagascar and the United Kingdom reported the results of a study of ciprofloxacin versus a combination of ciprofloxacin with injected aminoglycoside2 on Madagascar residents who were suspected of plague infections during 2020–2024. The results of the 10-day, 933-patient study showed that ciprofloxacin alone was “noninferior” to the combination therapy.
1. CAS Reg. No. 85721-33-1.
2. Aminoglycosides are Gram-negative antibacterial medications such as streptomycin. The specific one is not mentioned in the report.
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