Cancer
Ciprofloxacin is active in six of eight in vitro assays used as rapid screens for the detection of genotoxic effects, but is not active in in vivo assays of genotoxicity. Long-term carcinogenicity studies in rats and mice resulted in no carcinogenic or tumorigenic effects due to ciprofloxacin at daily oral dose levels up to 250 and 750 mg/kg to rats and mice, respectively (about 1.7 and 2.5 times the highest recommended therapeutic dose based upon mg/m2). Results from photo co-carcinogenicity testing indicate ciprofloxacin does not reduce the time to appearance of UV-induced skin tumors as compared to vehicle control. Other
The other black box warning is that ciprofloxacin should not be used in people with myasthenia gravis due to possible exacerbation of muscle weakness which may lead to breathing problems resulting in death or ventilator support. Fluoroquinolones are known to block neuromuscular transmission. There are concerns that fluoroquinolones including ciprofloxacin can affect cartilage in young children.Clostridium difficile-associated diarrhea is a serious adverse effect of ciprofloxacin and other fluoroquinolones; it is unclear whether the risk is higher than with other broad-spectrum antibiotics.A wide range of rare but potentially fatal adverse effects reported to the U.S. FDA or the subject of case reports includes aortic dissection, toxic epidermal necrolysis, Stevens–Johnson syndrome, low blood pressure, allergic pneumonitis, bone marrow suppression, hepatitis or liver failure, and sensitivity to light. The medication should be discontinued if a rash, jaundice, or other sign of hypersensitivity occurs.Children and the elderly are at a much greater risk of experiencing adverse reactions.
Compared to the 250- and 500-mg immediate-release tablets, the 500-mg and 1000-mg XR tablets provide higher Cmax, but the 24‑hour AUCs are equivalent. Ciprofloxacin immediate-release tablets contain ciprofloxacin as the hydrochloride salt, and the XR tablets contain a mixture of the hydrochloride salt as the free base. Chemical properties
Ciprofloxacin is 1-cyclopropyl-6-fluoro-1,4-dihydro-4-oxo-7-(1-piperazinyl)-3-quinolinecarboxylic acid. Its empirical formula is C17H18FN3O3 and its molecular weight is 331.4 g/mol. It is a faintly yellowish to light yellow crystalline substance.Ciprofloxacin hydrochloride (USP) is the monohydrochloride monohydrate salt of ciprofloxacin. It is a faintly yellowish to light yellow crystalline substance with a molecular weight of 385.8 g/mol. Its empirical formula is C17H18FN3O3HCl•H2O. Usage
Ciprofloxacin is the most widely used of the second-generation quinolones. In 2010, over 20 million prescriptions were written, making it the 35th-most commonly prescribed generic drug and the 5th-most commonly prescribed antibacterial in the U.S.

History
The first members of the quinolone antibacterial class were relatively low-potency drugs such as nalidixic acid, used mainly in the treatment of urinary tract infections owing to their renal excretion and propensity to be concentrated in urine. In 1979, the publication of a patent filed by the pharmaceutical arm of Kyorin Seiyaku Kabushiki Kaisha disclosed the discovery of norfloxacin, and the demonstration that certain structural modifications including the attachment of a fluorine atom to the quinolone ring leads to dramatically enhanced antibacterial potency. In the aftermath of this disclosure, several other pharmaceutical companies initiated research and development programs with the goal of discovering additional antibacterial agents of the fluoroquinolone class.