• Antibiotics
  • Pharmacology

Ciprofloxacin: Indications, MOA, Dosage and Side effects

  • 6 minutes, 3 seconds
  • Antibiotics
  • 2020-08-04 18:22:55

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Ciprofloxacin is a 4-quinolone derivative. It is a fluorinated analogs of nalidixic acid.

Ciprofloxacin is highly active against gram-negative bacteria and moderately active against gram-positive bacteria.

Trade name; Cipro, Cipro I.V., Cipro XR, Proquin XR


Ciprofloxacin is indicated for the treatment of infections caused by ciprofloxacin-sensitive microbes. (including Campylobacter jejuni, Citrobacter diversus, Citrobacter freundii, Enterobacter cloacae, Escherichia coli, Haemophilus influenzae, Haemophilus parainfluenzae, Klebsiella pneumoniae,  Morganella morganii, Neisseria gonorrhoeae, Proteus mirabilis, Proteus vulgaris, Providencia rettgeri, Providencia stuartii, Pseudomonas aeruginosa, Serratia marcescens, Shigella flexneri, and Shigella sonnei) and gram-positive organisms (including Enterococcus faecalis, Staphylococcus aureus, Staphylococcus epidermidis, and Streptococcus pneumoniae)

Treatment of urinary tract infections caused by E. coli, K. pneumoniae, Enterococcus faecalis, P. mirabilis, or P. aeruginosa.

Acute uncomplicated pyelonephritis caused by E. coli e.r.

Upper and lower respiratory tract infections(but not pneumococcal),

Ciprofloxacin is used against Bacillus anthracis.

Urinary tract infections (UTIs), particularly when resistant to cotrimoxazole

Sexually transmitted diseases (STDs)/pelvic inflammatory diseases (PIDs): chlamydia, gonorrhea

sinusitis caused by gram negative organisms

Skin, soft tissue, and bone & joint infections by gram-negative organisms

infectious Diarrhea due to Shigella, Salmonella, E. coli, Campylobacter

Septicaemia and meningococcal meningitis contacts.

chronic bacterial prostatitis

Ciprofloxacin is ineffective in most anaerobic infections.

Mechanism of action

Ciprofloxacin like other quinolones are bactericidal.

Cipfofloxacin inteferes with DNA synthesis by inhibiting an enzyme known as topoisomerase II (DNA gyrase) and topoisomerase IV. This enzyme is responsible for the unwinding and supercoiling of bacterial DNA before it replicates. By inhibiting this enzyme, ciprofloxacin causes bacterial cells to die.

In gram negative it inhibits bacterial topoisomerase II), and therefore,

DNA supercooling whereas ingram positive organisms it inhibits topoisomerase IV and thereby interfere with separation of replicated chromosomal DNA.

What is DNA gyrase?

DNA gyrase or topoisomerase II is an enzyme that permits the orderly accommodation of a long bacterial chromosome of about 1000 µm in a bacterial cell of ~1 µm.

Within the chromosomal strand, double-stranded DNA has a double helical configuration. This double-stranded DNA, in turn, is arranged in loops that are shortened by a process of supercoiling.

DNA gyrase is the enzyme responsible for catalysis of this operation. It has a role in the opening, underwinding, and closing the DNA double strand in such a way that the full loop need not be rotated.

Ciprofloxacin appears to prevent specifically the resealing of opened strands and thereby killing the bacteria.


Ciprofloxacin is absorbed from GI tract after oral ingestion.

Iron, calcium containing foods or drugs limit its absorption

Ciprofloxacin is systemically available in about 70-80% of an oral dose taken.

Peak plasma concentration is achieved 0.5-2 hours after oral dosing.

Absorption may be delayed by presence of food but it is not substantially affected overall.

Upon administration, the drug is widely distributed in all body compartments including the eye and the cerebrospinal fluid, but the concentrations are only about 10% of those in plasma when the meninges are not inflamed.

Ciprofloxacin crosses placenta and is distributed into the breastmilk. High concentrations are achieved in bile.

Ciprofloxacin is primarily excreted by kidneys through glomerular filtration and active tubular secretion but its elimination is inhibited by probenecid.

Non-renal clearance may account for about a third of elimination and includes hepatic metabolism, biliary excretion, and possibly transluminal secretion across the interstinal mucosa.

Reduce dose in renal dysfunction

It has a half-life of four hours but may be prolonged in severe renal failure and to some extent in elderly.

Plasma protein binding ranges from 20-40%.

ciprofloxacin, has the additional advantage of being available for intravenous use.

About 40-50 percent of the orally taken dose is eliminated unchanged in urine and about 15% as metabolites. Fecal excretion over 5 days has accounted for 20 to 35 percent of the oral dose.

At least four metabolites have been identified. Oxociprofloxacin appears to be the major urinary metabolite and sulphociprofloxacin is the primary fecal metabolite.

Only small amounts of ciprofloxacin are removed by haemodialysis or peritoneal dialysis.

Dosage and administration

The drug should be taken with a lot of fluids, with or without meals.

The normal dose ranges between 250 mg to 750 mg twice daily.

Elderly people should be given a low dose as possible.

In patients with reduced renal function , the half-life of the drug is prolonged therefore the dose might be adjusted.

➤In treatment of inhalation anthrax after exposure or to treat inhalation anthrax

Adults and adolescents. 500 mg every 12 hr for 60 days.

Children. 15 mg/kg every 12 hr for 60 days.

➤To treat acute sinusitis

Adults. 500 mg every 12 hr for 10 days.

➤To treat bone and joint infections

For mild to moderate infections, 500 mg every 12 hr for 4 to 6 wk. For severe or complicated infections, 750 mg every  12 hr for 4 to 6 wk.

➤ To treat skin and soft-tissue infections

Adults. For mild to moderate infections, 500 mg every 12 hr for 7 to 14 days. For severe or complicated infections, 750 mg every 12 hr for 7 to 14 days.

➤ To treat chronic bacterial prostatitis Adults. 500 mg every 12 hr for 28 days.

➤ To treat infectious diarrhea

Adults. 500 mg every 12 hr for 5 to 7 days.

➤ To treat UTI

Adults. For acute uncomplicated infections, 100 mg every 12 hr for 3 days. For mild to moderate infections, 250 mg every 12 hr for 7 to 14 days. For severe or complicated infections, 500 mg every 12 hr for 7 to 14 days.

➤ To treat complicated UTI or acute uncomplicated

Adults. 1,000 mg daily for 7 to 14 days.

➤ To treat acute cystitis caused by E. coli, P. mirabilis, E. faecalis, or Staphylococcus saprophyticus e.r. tablets

Adults. 500 mg daily for 3 days.

➤ To treat lower respiratory tract infections

Adults. For mild to moderate infections, 500 mg every 12 hr for 7 to 14 days. For severe or complicated infections, 750 mg every 12 hr for 7 to 14 days.

➤To treat intra-abdominal infections

Adults. 400 mg every 8 hr along with parenteral metronidazole.

➤ To treat mild to severe nosocomial pneumonia Adults. 400 mg every 8 hr.

➤ To treat typhoid fever caused by Salmonella typhi

Adults. 500 mg every 12 hr for 10 days.

➤ To treat uncomplicated urethral or cervical gonococcal infections caused by N. gonorrhoeae a single dose of 250 mg.

The duration depends on the severity, clinical response and bacteriological results. For acute infections the usual treatment period is 5-10 days.

Dose adjustment 

Dosage reduced to 250 to 500 mg every 12 hr if creatinine clearance is 30 to 50 ml/min/1.73 m2; and to 250 to 500 mg  P.O. or 200 to 400 mg I.V. every 18 hr if  creatinine clearance is 5 to 29 ml/min/1.73 m2.

➤ To treat acute cystitis caused by E. coli or K. pneumoniae e.r. tablets (proquin xr)  Adults. 500 mg daily for 3 days with evening meal.

Use in pregnancy

Ciprofloxacin belongs to pregnancy category C

Since they can damage epiphyseal chondrocytes and joint cartilages in laboratory animals, gyrase inhibitors should not be used during pregnancy, lactation, and periods of growth.

Contraindicated in pregnancy and in children (inhibition of  chondrogenesis)

Drug Interactions

Antacids, iron supplements, sucralfate, or zinc decrease ciprofloxacin absorption

Ciproflozacin increases plasma levels of clozapine, methotrexate, methylxanthines, olanzapine, therefore increasing the risk of serious adverse reactions such as toxicity .

Its use with cyclosporine causes an elevated serum creatinine and blood cyclosporine levels NSAIDs

Increased risk of seizures with high doses of ciprofloxacin

Its use with oral anticoagulants enhances anticoagulant effects

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