Formulary
Ciprofloxacin: Uses, Dosing, Side Effects and Indian Brand Names
Ciprofloxacin is a second-generation fluoroquinolone with the best anti-Pseudomonal activity of oral antibiotics, first-line for complicated UTIs and typhoid in adults, though rising resistance in India limits empiric use.
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Ciprofloxacin: Uses, Dosing, Side Effects and Indian Brand Names
Ciprofloxacin is a second-generation fluoroquinolone with the best anti-Pseudomonal activity of oral antibiotics, first-line for complicated UTIs and typhoid in adults, though rising resistance in India limits empiric use.
NEET PG High-Yield: DNA gyrase (Gram-negatives) and topoisomerase IV (Gram-positives) inhibition. Concentration-dependent killing. Best oral anti-Pseudomonal activity. Schedule H1 drug in India. Tendon rupture (Achilles) -- potentiated by steroids and age >60. CYP1A2 inhibitor (theophylline interaction). Chelation with divalent cations. Avoided in children (arthropathy risk). Anthrax prophylaxis. Myasthenia gravis caution. Rising resistance in India makes local antibiograms essential.
Clinical overview
Ciprofloxacin is the prototypical second-generation fluoroquinolone and remains one of the most important antibiotics for Gram-negative infections, particularly those caused by Pseudomonas aeruginosa -- a property that distinguishes it from most other oral antibiotics. It achieves excellent concentrations in the urinary tract, respiratory tract, bone, and prostate, making it valuable for complicated UTIs, osteomyelitis, chronic bacterial prostatitis, and Gram-negative pneumonias. Ciprofloxacin is the drug of choice for typhoid fever (enteric fever) caused by Salmonella typhi in adults, and for empiric treatment of infectious diarrhoea in adults. However, fluoroquinolone resistance in India is a major and growing concern: ICMR data shows ciprofloxacin resistance rates of 70-80% in E. coli urinary isolates and rising resistance in Salmonella. This makes local antibiogram data essential before empiric use. The fluoroquinolone class carries serious adverse effects including tendon rupture (especially Achilles tendon, potentiated by corticosteroids and age >60), QT prolongation, peripheral neuropathy, and CNS effects. The FDA has issued multiple warnings restricting fluoroquinolone use for uncomplicated infections where alternatives exist. Ciprofloxacin chelates divalent cations (calcium, iron, magnesium, zinc, aluminium), and oral absorption is dramatically reduced by concurrent antacids, dairy products, or supplements -- a critical counselling point.
Pharmacological class
Ciprofloxacin belongs to the Fluoroquinolones (Second-Generation) class. Inhibits bacterial DNA gyrase (topoisomerase II) and topoisomerase IV, which are essential for DNA supercoiling, replication, repair, and transcription. DNA gyrase is the primary target in Gram-negative bacteria, while topoisomerase IV is the primary target in Gram-positive bacteria. This dual-target mechanism contributes to its broad spectrum. Ciprofloxacin is bactericidal and exhibits concentration-dependent killing.
Indian brand names and formulations
Available as: Ciplox (Cipla), Cifran (Sun/Ranbaxy), Ciprobid (Zydus), Quintor (Torrent).
Tablets: 250 mg, 500 mg, 750 mg. Extended-release tablets: 500 mg, 1000 mg. IV infusion: 200 mg/100 mL. Eye drops: 0.3%. Ear drops: 0.3% (with dexamethasone in FDC). Ointment: 0.3% (ophthalmic).
Regulatory status
Ciprofloxacin is classified under Schedule H1 in India under the Drugs and Cosmetics Act, 1940. Schedule H1 drug in India since 2014. Sale requires a prescription that must be retained by the pharmacist. Records of sale must be maintained. This stricter scheduling reflects antimicrobial stewardship concerns due to rising fluoroquinolone resistance.
Indications
- Complicated urinary tract infections and pyelonephritis
- Typhoid (enteric) fever in adults (where susceptible)
- Infectious diarrhoea (bacterial gastroenteritis in adults)
- Chronic bacterial prostatitis
- Pseudomonas infections (including malignant otitis externa)
- Osteomyelitis (Gram-negative, including Pseudomonas)
- Anthrax (post-exposure prophylaxis and treatment)
- Febrile neutropenia (empiric, with or without an anti-Gram-positive agent)
Dosing
UTI (uncomplicated): 250-500 mg twice daily for 3 days. Complicated UTI/pyelonephritis: 500 mg twice daily for 7-14 days. Typhoid: 500 mg twice daily for 7-14 days. Bone and joint infections: 500-750 mg twice daily for 4-6 weeks. IV: 200-400 mg every 8-12 hours. Anthrax prophylaxis: 500 mg twice daily for 60 days.
Contraindications
- History of tendon disorders related to fluoroquinolone use
- Concomitant use with tizanidine (marked increase in tizanidine levels via CYP1A2 inhibition)
- Children and adolescents (<18 years) except for specific indications (anthrax, CF-related Pseudomonas) due to risk of arthropathy and tendon damage
- Myasthenia gravis (may exacerbate muscle weakness)
Adverse effects
- GI disturbances (nausea, diarrhoea, abdominal pain -- most common)
- Tendinopathy and tendon rupture (Achilles most common; risk increased with age >60, corticosteroids, renal impairment, solid organ transplant)
- QT prolongation and risk of arrhythmia
- Peripheral neuropathy (may be irreversible)
- CNS effects (headache, dizziness, insomnia, rarely seizures -- lower seizure threshold)
- Photosensitivity
- Clostridioides difficile-associated diarrhoea
- Aortic aneurysm and dissection (rare but recognised class effect)
Drug interactions
- Divalent and trivalent cations (antacids with Al/Mg, calcium supplements, iron, zinc, sucralfate): chelation reduces ciprofloxacin absorption by >90%; separate by at least 2 hours before or 6 hours after
- Theophylline: ciprofloxacin inhibits CYP1A2, increasing theophylline levels and risk of toxicity
- Tizanidine: contraindicated -- ciprofloxacin increases tizanidine AUC by 10-fold
- Warfarin: may increase INR; monitor closely
- NSAIDs: may lower seizure threshold when combined with ciprofloxacin
- Dairy products and calcium-fortified foods: reduce absorption (take ciprofloxacin 2 hours before or 6 hours after)
Pregnancy and lactation
Category C. Generally avoided in pregnancy due to theoretical risk of cartilage damage in the foetus (demonstrated in animal studies). Used only for life-threatening infections with no alternatives (e.g., anthrax). Nitrofurantoin, amoxicillin, or cephalexin are preferred for UTI in pregnancy.
Exam-style clinical scenario
A 65-year-old man on prednisolone for polymyalgia rheumatica develops acute heel pain 5 days after starting ciprofloxacin for a UTI. Examination reveals tenderness and swelling of the Achilles tendon. Diagnosis? Fluoroquinolone-induced tendinopathy -- stop ciprofloxacin immediately, immobilise the ankle, and switch to an alternative antibiotic. Risk factors: age >60 + concurrent corticosteroid use.
Cost in India
Rs 15-40 for a strip of 10 tablets (500 mg). IV: Rs 30-60 per 200 mg/100 mL infusion. Eye drops: Rs 30-50.
Clinical governance
Author: MedNext Editorial Team. Clinical reviewer: Awaiting clinical review. Jurisdiction: India (Drugs and Cosmetics Act, 1940). Sources: CIMS India, Indian Pharmacopoeia. Publication state: Awaiting clinical review. Correction: Report errors at support@mednext.academy.
Frequently Asked Questions
Why is ciprofloxacin Schedule H1 while amoxicillin is Schedule H?
Schedule H1 was created in 2014 specifically to combat antimicrobial resistance. It imposes stricter dispensing controls: the pharmacist must maintain a register of sales, and the prescription must be retained. Fluoroquinolones, third-generation cephalosporins, and carbapenems were placed in H1 because of alarming resistance rates. India has among the highest fluoroquinolone resistance rates globally, partly due to over-the-counter dispensing that H1 scheduling aims to curtail.
Why is ciprofloxacin avoided in children?
Animal studies showed that fluoroquinolones cause arthropathy (cartilage damage) in weight-bearing joints of juvenile animals. While human data from limited paediatric use has not confirmed irreversible joint damage, the risk is considered unacceptable when safer alternatives exist. Exceptions are made for cystic fibrosis-related Pseudomonas infections, anthrax prophylaxis, and febrile neutropenia where the benefit clearly outweighs the risk.
How does ciprofloxacin resistance develop?
Resistance develops through chromosomal mutations in the genes encoding DNA gyrase (gyrA, gyrB) and topoisomerase IV (parC, parE), reducing drug binding affinity. Additionally, plasmid-mediated quinolone resistance (PMQR) genes encode proteins that protect topoisomerases, efflux pumps that extrude the drug, and enzymes that acetylate ciprofloxacin. Sub-therapeutic dosing and inappropriate prescribing accelerate selection of resistant mutants.
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