norfloxacin

Action and Spectrum

Actions and Spectrum: 

norfloxacin inhibits bacterial DNA synthesis by binding to the DNA gyrase enzyme. This action disrupts the normal functioning of bacterial cells, leading to their death. 

norfloxacin has a broad activity spectrum against gram-positive and gram-negative bacteria. It is particularly effective against Escherichia coli, Salmonella species, Shigella species, and other Enterobacteriaceae family members. It is also active against gram-positive bacteria, including Staphylococcus aureus and Streptococcus pneumoniae. 

Drug Interaction

Adverse Reaction

Frequency defined 

1-10% 

nausea 

headache 

<1% 

Skin erythema 

Proteinuria 

Epiphora 

Increased serum 

Arthralgia 

Euphoria 

Drowsiness 

Eosinophilia 

Frequency not defined 

Hyperglycemia 

Hypoglycemia 

Tendon rupture 

Tremor 

Black Box Warning

Black Box Warning: 

norfloxacin has a black box warning, the most severe type of warning issued by the U.S. Food and Drug Administration (FDA). The black box warning of norfloxacin is as follows: 

• Tendinitis and tendon rupture: fluoroquinolone antibiotics, including norfloxacin, have been associated with an increased risk of tendinitis and tendon rupture, particularly in elderly patients and those who are taking corticosteroids. Tendinitis and tendon rupture can occur in any tendon, but the most commonly affected are the Achilles tendon and the rotator cuff of the shoulder. 

• Peripheral neuropathy: fluoroquinolones have been associated with an increased risk of peripheral neuropathy, which is a condition that affects the nerves in the hands and feet. Symptoms of peripheral neuropathy can include pain, burning, tingling, numbness, and weakness. 

Contraindication / Caution

Contraindication/Caution: 

• Hypersensitivity: norfloxacin is contraindicated in patients who have a history of hypersensitivity or allergic reactions to the drug or other fluoroquinolones. 

• Tendinitis and tendon rupture: fluoroquinolone antibiotics, including norfloxacin, have been associated with an increased risk of tendinitis and tendon rupture, particularly in elderly patients and those who are taking corticosteroids.  

• Central nervous system disorders: norfloxacin may cause central nervous system (CNS) side effects, such as seizures, tremors, and hallucinations, particularly in patients who have a history of CNS disorders or who are taking medications that lower the seizure threshold. 

• Myasthenia gravis: norfloxacin should be used with caution in patients with myasthenia gravis, a neuromuscular disorder that can cause muscle weakness, as the medication may exacerbate this condition. 

• QT prolongation: norfloxacin can cause QT prolongation, a heart rhythm disorder that can be potentially life-threatening, particularly in patients with a history of QT prolongation, electrolyte imbalances, or those taking medications that can cause QT prolongation. 

• Pregnancy and lactation: norfloxacin should be used with caution in pregnant and breastfeeding women, as the medication may be associated with harm to the fetus or nursing infant. 

• Children and adolescents: norfloxacin should not be used in children and adolescents under 18 years of age, as it can cause damage to growing cartilage and bone tissue. 

Pregnancy / Lactation

Pregnancy consideration:  

Pregnant females should not take this medicine as it has teratogenic on the developing fetus. 

Breastfeeding warnings: lactating females should not breastfeed during the medication. 

Pregnancy category: 

• Category A: Satisfactory and well-controlled studies show no risk to the fetus in the first or later trimester. 

• Category B: There is no affirmation of risk to the fetus found in animal reproduction studies, and there are not enough studies on pregnant women. 

• Category C: Adverse effects on the fetus found with evidence in animal reproduction studies and no adequate evidence for a product in humans; Pregnant women must take care of the potential risks. 

• Category D: There is adequate data available with sufficient evidence of human fetal risk from various platforms. However, despite potential dangers may be used only in emergency cases for potential benefits. 

• Category X: Drugs listed in this category outweigh risks over benefits. The drug is not for pregnant women. 

• • Category N: No data is available for the drug under this category. 

Pharmacology

Pharmacology: 

norfloxacin is a fluoroquinolone antibiotic used to treat bacterial infections, including urinary tract infections, gonorrhea, prostatitis, and gastroenteritis. It works by inhibiting the bacterial DNA gyrase enzyme, essential for bacterial DNA replication and repair. 

Pharmacodynamics: 

The pharmacodynamics of norfloxacin involves its interaction with bacterial DNA gyrase enzyme, which is essential for bacterial DNA replication and repair. norfloxacin binds to the A subunit of DNA gyrase, thereby inhibiting its activity and preventing bacterial DNA synthesis. 

norfloxacin is bactericidal, meaning it kills bacteria rather than just inhibiting their growth. Its bactericidal effect is concentration-dependent and time-dependent, with higher concentrations and longer exposure times leading to greater bacterial killing. 

norfloxacin is effective against a wide range of gram-negative bacteria, including Escherichia coli, Klebsiella pneumoniae, Proteus mirabilis, and Neisseria gonorrhoeae. Its activity against gram-positive bacteria and anaerobes is limited. 

Pharmacokinetics: 

Absorption 

norfloxacin is well absorbed after oral administration, with peak plasma concentrations achieved within 1-2 hours. Food intake does not significantly affect its absorption. 

Distribution 

norfloxacin has a volume of distribution of approximately 1-2 L/kg, indicating that it is widely distributed throughout the body. It penetrates well into tissues such as the prostate, urinary tract, and gastrointestinal tract, where it is effective against bacterial infections. 

Metabolism  

The drug is metabolised in the liver, with the main metabolite being desethyl-norfloxacin, which has reduced antimicrobial activity compared to the parent compound. 

Elimination and Excretion 

norfloxacin is primarily eliminated unchanged in the urine, with approximately 30-50% of a dose excreted unchanged within 24 hours. 

Adminstartion

Administration: 

The recommended adult dose of norfloxacin for uncomplicated urinary tract infections is 400 mg orally twice daily for 3 days. The recommended dose for complicated urinary tract infections, prostatitis, and gastroenteritis is 400 mg orally twice daily for 7-10 days. 

norfloxacin should be taken with a full glass of water, preferably at least 1 hour before or 2 hours after a meal, to ensure optimal absorption. Patients should avoid taking dairy or calcium-containing products simultaneously as norfloxacin, as they can interfere with its absorption. 

The norfloxacin dose may need to be adjusted for patients with impaired renal function based on their creatinine clearance. norfloxacin is not recommended for children, as its safety and efficacy in this population have not been established. 

Patient Information Leaflet

Patient information leaflet 

Generic Name: norfloxacin 

Pronounced: nor-flox-a-sin 

Why do we use norfloxacin? 

norfloxacin is a fluoroquinolone antibiotic used to treat various bacterial infections, primarily those caused by gram-negative bacteria. It is typically used in the treatment of: 

• Urinary tract infections (UTIs): norfloxacin is effective against most strains of bacteria that cause uncomplicated and complicated UTIs, including Escherichia coli, Klebsiella pneumoniae, Proteus mirabilis, and Enterobacter species. 

• Prostatitis: norfloxacin effectively treats acute and chronic bacterial prostatitis caused by susceptible bacteria. 

• Gastrointestinal infections: norfloxacin treats bacterial gastroenteritis caused by susceptible bacteria, including Campylobacter jejuni, Salmonella species, and Shigella species. 

• Sexually transmitted infections (STIs): norfloxacin treats uncomplicated gonorrhea caused by Neisseria gonorrhoeae. 

• Respiratory tract infections: norfloxacin is occasionally used to treat lower respiratory tract bacterial infections, such as acute exacerbations of chronic bronchitis caused by susceptible bacteria.