Usage
Levofloxacin is a broad-spectrum antibiotic prescribed for various bacterial infections. It is classified as a fluoroquinolone antibiotic. The drug works by inhibiting bacterial DNA gyrase and topoisomerase IV, enzymes essential for bacterial DNA replication and repair. This inhibition prevents bacterial growth and reproduction.
Alternate Names
Levofloxacin is also known internationally by the same name. A popular brand name under which it is marketed is Levaquin.
How It Works
Pharmacodynamics: Levofloxacin exerts its bactericidal action by inhibiting bacterial DNA gyrase and topoisomerase IV. These enzymes are crucial for bacterial DNA replication, transcription, repair, and recombination. By inhibiting these enzymes, levofloxacin disrupts bacterial DNA function and ultimately leads to bacterial cell death.
Pharmacokinetics: Levofloxacin is well-absorbed orally and reaches peak plasma concentrations within 1-2 hours. It has a bioavailability of nearly 100%. The drug is widely distributed throughout the body, including tissues and fluids. It is primarily eliminated unchanged through renal excretion. It has a half-life of approximately 6-8 hours.
Mode of Action/Receptor Binding: Levofloxacin directly targets bacterial DNA gyrase and topoisomerase IV, inhibiting their enzymatic activity. This interaction disrupts the supercoiling and decatenation of bacterial DNA, essential processes for DNA replication and cell division.
Elimination Pathways: Levofloxacin is primarily excreted unchanged in the urine (about 87%). A minor portion is metabolized in the liver.
Dosage
Standard Dosage
Adults:
The standard adult dosage of levofloxacin ranges from 250 mg to 750 mg once daily, administered orally or intravenously. The exact dose and duration of therapy depend on the specific infection being treated.
Children:
Levofloxacin is generally not recommended for children under 18 years of age except in specific cases like inhalational anthrax (post-exposure) or plague. The dosage for children older than 6 months who weigh 50kg or more is 500 mg once daily, and for children who weigh between 30kg and less than 50kg, it’s 250 mg every 12 hours. These pediatric doses are for specific infections and should be determined by a doctor.
Special Cases:
- Elderly Patients: Dosage adjustments may be needed in elderly patients due to age-related decline in renal function.
- Patients with Renal Impairment: Dose reduction is required for patients with creatinine clearance less than 50 mL/min. See detailed dosage adjustment table in FDA-approved labeling.
- Patients with Hepatic Dysfunction: No dosage adjustment is typically necessary for patients with hepatic impairment.
- Patients with Comorbid Conditions: Careful monitoring is advised for patients with conditions like diabetes or cardiovascular disease.
Clinical Use Cases
Dosing recommendations in specific medical settings can vary, and clinical guidelines should be consulted. Generally, intravenous administration is preferred for critically ill patients, while oral administration may be suitable for less severe infections.
Dosage Adjustments
Renal function is the primary determinant of dosage adjustments. The FDA-approved drug label provides specific guidance on dose modification based on creatinine clearance.
Side Effects
Common Side Effects:
Nausea, diarrhea, headache, insomnia, dizziness, and constipation.
Rare but Serious Side Effects:
Tendon rupture, peripheral neuropathy (nerve damage), severe mood or behavioral changes, hypoglycemia (low blood sugar), QT interval prolongation (abnormal heart rhythm).
Long-Term Effects:
Peripheral neuropathy and tendon damage can persist even after discontinuation of the drug.
Adverse Drug Reactions (ADR):
Anaphylaxis, Stevens-Johnson syndrome, toxic epidermal necrolysis, and Clostridium difficile-associated diarrhea.
Contraindications
Hypersensitivity to levofloxacin or other fluoroquinolones, history of quinolone-associated tendon rupture, epilepsy or other seizure disorders.
Drug Interactions
Levofloxacin interacts with antacids, sucralfate, multivitamins containing divalent or trivalent cations, warfarin, antidiabetic agents, drugs that prolong QT interval, NSAIDs, theophylline and certain urine drug tests. These interactions can affect levofloxacin absorption, enhance side effects, or alter the metabolism of other drugs. For specific examples refer to FDA label.
Pregnancy and Breastfeeding
Levofloxacin is generally avoided during pregnancy unless the potential benefits outweigh the risks. Although the drug is excreted in breast milk, it is considered acceptable to use with careful monitoring of the infant.
Drug Profile Summary
- Mechanism of Action: Inhibits bacterial DNA gyrase and topoisomerase IV.
- Side Effects: Nausea, diarrhea, headache, insomnia, dizziness, constipation, tendon rupture, peripheral neuropathy, severe mood changes, hypoglycemia, QT prolongation.
- Contraindications: Hypersensitivity, tendon rupture history, epilepsy, seizure disorders.
- Drug Interactions: Antacids, sucralfate, metal cations, warfarin, antidiabetics, QT prolonging drugs, NSAIDs.
- Pregnancy & Breastfeeding: Generally avoided in pregnancy; acceptable with monitoring during breastfeeding.
- Dosage: 250-750 mg/day (adults); pediatric dose varies with weight and infection.
- Monitoring Parameters: Renal function, blood glucose levels, signs of tendonitis, psychiatric status, ECG (for QT interval).
Popular Combinations
Levofloxacin is often used as monotherapy. Combination therapy may be warranted for specific infections like H. pylori.
Precautions
Pre-existing medical conditions like renal impairment, diabetes, and cardiac conditions should be carefully considered. Patients should be advised to maintain adequate hydration and avoid concomitant use of contraindicated drugs.
FAQs (Frequently Asked Questions)
Q1: What is the recommended dosage for Levofloxacin?
A: The standard adult dose is 250-750 mg once daily. Pediatric dosage depends on weight and indication.
Q2: What are the common side effects?
A: Nausea, diarrhea, headache, insomnia, dizziness, and constipation are common side effects.
Q3: What are the serious side effects of Levofloxacin?
A: Tendon rupture, peripheral neuropathy, severe mood changes, and QT prolongation are serious side effects.
Q4: What are the contraindications for Levofloxacin?
A: Hypersensitivity to fluoroquinolones, history of tendon rupture with fluoroquinolones, and epilepsy are contraindications.
Q5: What are the key drug interactions to be aware of?
A: Interactions occur with antacids, sucralfate, multivitamins with cations, warfarin, some antidiabetics, and drugs that prolong the QT interval.
Q6: Can Levofloxacin be used in pregnant or breastfeeding women?
A: It is generally avoided during pregnancy and can be used cautiously in breastfeeding mothers with infant monitoring.
Q7: What are the key monitoring parameters during Levofloxacin therapy?
A: Monitor renal function, blood glucose, signs of tendonitis, mental status, and ECG for QT prolongation.
Q8: How does Levofloxacin work?
A: It inhibits bacterial DNA gyrase and topoisomerase IV, essential enzymes for bacterial DNA replication and repair.
Q9: What infections is Levofloxacin commonly used to treat?
A: Urinary tract infections, pneumonia, sinusitis, skin infections, and some sexually transmitted infections.
