Ciprofloxacin Base/HCl

Product Story

Ciprofloxacin was synthesized in 1983 at Bayer AG in Wuppertal, Germany, by a team led by Dr. Klaus Grohe. It emerged from Bayer's systematic program to modify the quinolone scaffold, which had begun with nalidixic acid — the first quinolone antibiotic discovered by George Lesher at Sterling-Winthrop in 1962. The key breakthrough was the Grohe method: a novel one-step cyclization reaction that allowed incorporation of both a fluorine atom at C-6 and a piperazine ring at C-7 of the quinolone core. This dual substitution yielded a compound with dramatically improved potency, tissue penetration, and Gram-negative spectrum compared to earlier quinolones. Bayer launched ciprofloxacin as Ciprobay in 1987, and it rapidly became the world's best-selling fluoroquinolone.

Ciprofloxacin's mechanism is distinct from beta-lactams and macrolides: it inhibits two essential bacterial enzymes — DNA gyrase (topoisomerase II) and topoisomerase IV — that control DNA supercoiling and chromosome segregation during replication. By stabilizing the enzyme-DNA cleavage complex, ciprofloxacin converts these essential enzymes into cellular toxins that fragment the bacterial chromosome. Its particular potency against Pseudomonas aeruginosa set it apart from all earlier fluoroquinolones and most other oral antibiotics, making it the oral drug of choice for pseudomonal infections when IV therapy is not feasible. The fluorine atom at C-6 enhances both gyrase binding affinity and cell penetration, while the piperazine ring at C-7 extends Gram-negative coverage.

Ciprofloxacin is available in two API forms: the free base (CAS 85721-33-1), used for oral suspensions and some topical formulations, and the hydrochloride monohydrate salt (CAS 86393-32-0), used for tablets, IV infusion solutions, and ophthalmic preparations. The HCl salt provides superior aqueous solubility (~30 mg/mL) compared to the nearly water-insoluble base, enabling parenteral formulations. Ciprofloxacin's clinical significance was underscored after the 2001 anthrax attacks in the United States, when it became the FDA-designated first-line agent for post-exposure prophylaxis and treatment of inhalational anthrax, a role it retains today.

As of mid-2026, global ciprofloxacin API demand is estimated at 4,000-5,000 metric tons annually. China and India account for the majority of production, with Chinese manufacturers controlling the upstream fluoroquinolone intermediate supply chain (2,4-dichloro-5-fluoroacetophenone and cyclopropylamine). The ciprofloxacin market has seen significant consolidation since 2020, with several smaller producers exiting due to margin pressure. Price trends are influenced by intermediate availability, environmental compliance costs in China's chemical manufacturing provinces, and sustained demand from public health programs in emerging markets. KingWish supplies GMP-certified ciprofloxacin base and HCl meeting USP/EP/IP/CP standards.

Quality Specifications

Therapeutic Applications

• Urinary tract infections: First-line treatment for complicated UTIs, pyelonephritis, and prostatitis. Superior to most oral beta-lactams for deep tissue penetration in the urogenital tract.
• Respiratory tract infections: Effective for gram-negative pneumonias, acute exacerbations of bronchiectasis (particularly pseudomonal), and nosocomial respiratory infections.
• Gastrointestinal infections: Oral therapy for traveler's diarrhea, shigellosis, typhoid fever, and bacterial gastroenteritis. WHO-recommended for bloody diarrhea in children.
• Bone and joint infections: Excellent bone penetration makes ciprofloxacin a key oral agent for osteomyelitis caused by gram-negative organisms and for long-term suppression therapy.
• Anthrax: FDA-approved for post-exposure prophylaxis and treatment of inhalational anthrax (Bacillus anthracis). Listed in US Strategic National Stockpile for biodefense preparedness.