Antibiotic Drugs

Levofloxacin (Tavanic)

Levofloxacin is a synthetic, broad spectrum, second generation bactericidal fluoroquinolone.

Chemical structure

The empirical formula is C18H20FN3O4 and MW is 361.4.

Mechanism of action

Levofloxacin inhibits the enzyme bacterial DNA gyrase and prevents replication of bacterial DNA during bacterial growth and reproduction.

Site of action


Levofloxacin is rapidly and almost completely absorbed orally with peak plasma concentrations occurring within 1 to 2 hours. The absolute bioavailability of levofloxacin is approximately 99-100%, demonstrating complete oral absorption of levofloxacin. Levofloxacin is stereo-chemically stable in plasma and urine and does not invert metabolically to its enantiomer, D-ofloxacin. The elimination half-life of levofloxacin is 6 to 8 hours, which may be prolonged in patients with renal impairment.

Antimicrobial spectrum

Levofloxacin is active against aerobic gram-positive bacteria, aerobic gram- negative bacteria, anaerobic bacteria, chlamydophila pneumonia, chlamydophila psittaci, chlamydia trachomatis, legionella pneumophila, mycoplasma pneumonia, mycoplasma hominis and ureaplasma urealyticum

Indications, administration and dosage

Condition Dosage
Acute bacterial sinusitis 500 mg once daily for 10-14 days
Acute bacterial exacerbations of chronic bronchitis 500 mg once daily for 7-10 days
Community-acquired pneumonia 500 mg once or twice daily for 7-14 days
Pyelonephritis 500 mg once daily for 7-10 days
Complicated urinary tract infections 500 mg once daily for 7-14 days
Uncomplicated cystitis 250mg once daily for 3 days
Chronic bacterial prostatitis. 500 mg once daily for 28 days
Complicated skin and soft tissue infections 500 mg once or twice daily for 7-14 days
Inhalation Anthrax 500 mg once daily for 8 weeks

Precautions, contraindications and warnings

Levofloxacin is contraindicated in in patients hypersensitive to levofloxacin or other quinolones or any of the excipients, in patients with epilepsy, in patients with history of tendon disorders related to fluoroquinolone administrationin children or growing adolescents, during pregnancy and in breast-feeding women.

Adverse effects

The common adverse effects seen with levofloxacin are moniliasis, insomnia, headache, dizziness, dyspnea , nausea, diarrhea, constipation, abdominal pain, vomiting, dyspepsia, rash, pruritus.

Technical Description on Levofloxacin (Tavanic)

Levofloxacin is a synthetically derived second generation fluoroquinolone.

Chemical structure

In this formulation levofloxacin is present as levofloxacin hemihydrate. It is a chiral fluorinated carboxyquinolone, is the pure (-)-(S)-enantiomer of the racemic drug substance ofloxacin. The molecular formula is C18H20FN3O4 and MW is 361.4.

Preparations available

Oral – Tablets of 250/500 mg

For IV use - 5 mg/ml

Mechanism of action

Levofloxacin like other fluoroquinolones (FQs) inhibits the enzyme bacterial DNA gyrase that causes small cuts in the DNA, causes negative supercoiling and then re-ligates the cut ends. This helps in averting positive supercoiling which may occur in excess. The DNA gyrase comprises of two A and two B subunits: The A subunit leads to small cuts in the DNA, B subunit then brings about negative supercoiling and afterwards the A subunit causes re-ligation. Levofloxacin attaches to A subunit with great affinity and restricts the above mentioned function of the DNA gyrase enzyme. The predominant target in gram-positive bacteria is an analogous enzyme topoisomerase IV that nicks and separates daughter DNA strands once the DNA replication is complete. The damaged DNA leads to formation of exonucleases resulting in digestion of the DNA and this possibly contributes to the bactericidal action of levofloxacin.

The cells of mammals have the enzyme topoisomerase II instead of DNA gyrase or topoisomerase IV which possesses very little affinity for levofloxacin resulting in minimal damage to the host tissue.


Levofloxacin is active against the following organisms:

Aerobic Gram-positive bacteria

  • Bacillus anthracis
  • Staphylococcus aureus which are sensitive to methicillin.
  • Staphylococcus saprophyticus
  • Streptococci, group C and G and agalactiae
  • Pneumococci
  • Streptococcus pyogenes

Aerobic Gram- negative bacteria

  • Eikenella corrodens
  • Haemophilus influenzae and parainfluenzae
  • Klebsiella oxytoca
  • Moraxella catarrhalis
  • Pasteurella multocida
  • Proteus vulgaris
  • Providencia rettgeri

Anaerobic bacteria

  • Peptostreptococcus


  • Chlamydophila pneumoniae and psittaci
  • Chlamydia trachomatis
  • Legionella pneumophila
  • Mycoplasma pneumonia and hominis
  • Ureaplasma urealyticum


Resistance is mainly because of chromosomal mutation (Quinolone-Resistance Determining Regions {QRDRs}) forming a DNA gyrase or topoisomerase IV with reduced affinity for levofloxacin. Another common mechanism is reduced permeability/increased efflux of levofloxacin across bacterial membranes. Like other FQs levofloxacin, FQ-resistant mutants are not easily selected hence resistance develops slowly to FQs. However, increasing resistance has been reported among Salmonella, Pseudomonas, staphylococci, gonococci, pneumococci and C. jejuni.

Due to the unique mechanism of action plasmid mediated transferable resistance perhaps does not occur.

A Qnr protein has been seen that offers protection to the DNA gyrase from damage by the FQs. Also modification of levofloxacin can be caused by a different type acetyltransferase which is similar to the one which modifies aminoglycoside.

Resistance to levofloxacin due to spontaneous mutation in vitro is a rare occurrence. Although cross-resistance has been observed between levofloxacin and some other fluoroquinolones, some microorganisms resistant to other fluoroquinolones may be susceptible to levofloxacin.


Levofloxacin is absorbed swiftly and to a good extent orally. It attains maximal plasma levels within one to two hours. The bioavailability of levofloxacin is approximately 99-100%. It is extensively distributed into body tissues except in CSF. Plasma protein binding is about 30 to 40%. Only insignificant amounts are metabolised, to inactive metabolites. The elimination half-life of levofloxacin is 6 to 8 hours, which may be prolonged in patients with renal impairment.

These metabolites have little relevant pharmacological activity. Levofloxacin is not removed by peritoneal dialysis or haemodialysis.

Therapeutic uses and dosage

Condition Dosage
Acute bacterial sinusitis 500 mg OD for 10 days to one week
Acute bacterial exacerbations of chronic bronchitis, Community-acquired pneumonia, Pyelonephritis, urinary system infections, Infections of skin and appendages (complicated) 500 mg OD for 1-2 weeks
Inhalation Anthrax 500 mg OD for 8 weeks
Uncomplicated cystitis 250 mg OD for three days
Chronic prostatitis due to bacteria 500 mg OD for 4 weeks

Drug interactions

  • Iron, magnesium, zinc or aluminium containing salts

Absorption of levofloxacin is significantly decreased when administered with Fe2+ salts, or Mg2+ or Al+ containing antacids, formulations containing zinc or didanosine.

  • Sucralfate

When levofloxacin is administered with sucralfate, its bioavailability is decreased significantly.

  • Theophylline, NSAIDs

When levofloxacin is given with theophylline or NSAIDS it lowers the seizure threshold.

  • Cimetidine and probenecid

Cimetidine and probenecid inhibit the renal tubular secretion thereby reducing the renal excretion of levofloxacin.

  • Vitamin K antagonists

If vitamin K antagonists are prescribed simultaneously with levofloxacin it can lead to increased chances of bleeding.

  • QT interval prolongation

Levofloxacin should be cautiously used along with drugs causing QT prolongation.

Special population


Animal studies have shown damage to the weight bearing joints in the foetus. So, levofloxacin should be avoided in pregnancy.


Levofloxacin is secreted during lactation and hence it should be avoided.


Animal studies report no impairment in fertility or reproductive system.

Renal impairment

The pharmacokinetics of levofloxacin is affected by renal impairment. Dose should be reduced in patients with renal impairment.

Impaired liver function

As levofloxacin is not metabolised to any significant extent by the liver, dose alterations are not essential in hepatic impairment.

Paediatric population

Levofloxacin is contraindicated in children and growing adolescents

Warnings and precautions

  • Tendinopathy and Tendon Rupture

Levofloxacin is linked with an increased risk of inflammation of tendon and rupture of the tendon and it commonly involves the Achilles tendon.

  • Hepatotoxicity

Reports of severe liver toxicity have been reported with levofloxacin. However clinical trials have shown no such toxicity.

  • Central Nervous System Effects

Convulsions, toxic psychoses are reported in patients receiving levofloxacin. Fluoroquinolones may cause raised intracranial pressure and restlessness and anxious behaviour.

  • Clostridium difficile-Associated enterocolitis

Clostridium difficile-associated enterocolitis can be seen with levofloxacin.

  • Peripheral Neuropathy

Paresthesias, dysesthesias and weakness have been seen with levofloxacin.

  • Prolongation of the QT Interval

Levofloxacin can lead to prolongation of the QT interval and arrhythmia.

  • Musculoskeletal Disorders

An increased incidence of joint pain and inflammation and gait abnormality may be seen in children receiving levofloxacin. Levofloxacin is indicated in children (≥6 months of age) only for the prevention of inhalational anthrax (post-exposure).

  • Changes in blood glucose level

Increased and decreased blood glucose levels have been seen with levofloxacin, generally in diabetic patients receiving simultaneous antidiabetic medications.

  • Photo-toxicity

Moderate to severe photo-toxicity reactions may occur with levofloxacin.

  • Patients with G-6- phosphate dehydrogenase deficiency

Patients with glucose-6-phosphate dehydrogenase deficiency are prone to haemolytic reactions.

  • Severe bullous reactions

Stevens-Johnson syndrome or toxic epidermal necrolysis have been reported with levofloxacin.


Levofloxacin is contraindicated in following conditions:

  • in patients hypersensitive to levofloxacin or other quinolones or any of the excipients
  • in patients with epilepsy
  • in patients with history of tendon disorders related to fluoroquinolone administration in children or growing adolescents
  • during pregnancy
  • in breast-feeding women

Adverse effects

The common adverse effects seen with levofloxacin are:

  • Giddiness, headache
  • Candidiasis
  • Sleep disturbances
  • Breathlessness
  • Vomiting, loose stools, pain in the abdomen
  • Skin rashes, increased itching
  • Vaginitis
  • Oedema, reactions and pain at the injection site

Increased or sometimes decreased blood glucose levels, increased serum potassium levels

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