Microbiology: Levofloxacin is the L-isomer of the racemate, ofloxacin, a quinolone antimicrobial agent. The antibacterial activity of ofloxacin resides primarily in the L-isomer. The mechanism of action of levofloxacin and other fluoroquinolone antimicrobials involves inhibition of DNA gyrase (bacterial topoisomerase II), an enzyme required for DNA replication, transcription, repair and recombination.
Levofloxacin has in vitro activity against a wide range of gram-negative and gram-positive microorganisms. Levofloxacin is often bactericidal at concentrations equal to or slightly greater than inhibitory concentrations.
Fluoroquinolones differ in chemical structure and mode of action from β-lactam antibiotics. Fluoroquinolones may, therefore, be active against bacteria resistant to β-lactam antibiotics. Resistance to levofloxacin due to spontaneous mutation in vitro is a rate occurrence (range, 10-8 to 10-10). Although cross-resistance has been observed between levofloxacin and some other fluoroquinolones, some microorganisms resistant to other fluoroquinolones may be susceptible to levofloxacin.
Levofloxacin has been shown to be active against most strains of the following microorganisms both in vitro and in clinical infections as described in aerobic gram-positive microorganisms: Enterococcus faecalis, Staphylococcus aureus, Streptococcus pneumonia, Streptococcus pyogenes; aerobic gram-negative microorganisms: Enterobacter cloacae, Escherichia coli, Haemophilus influenzae, Haemophilus parainfluenzae, Klebsiella pneumoniae, Legionella pneumophila, Moraxella catarrhalis, Proteus mirabilis, Pseudomonas aeruginosa; other microorganisms: Chlamydia pneumoniae, Mycoplasma pneumoniae.
Pharmacokinetics: Absorption: Levofloxacin is rapidly, essentially and completely absorbed after oral administration. Peak plasma concentrations are usually attained 1-2 hrs after oral dosing. The absolute bioavailability of a 500-mg oral dose of levofloxacin is approximately 99%. Levofloxacin pharmacokinetics is linear and predictable after single and multiple oral dosing regimens. Steady state is reached within 48 hrs following a 500-mg once daily regimen. The peak and trough plasma concentrations attained following multiple once daily oral 500-mg regimens were approximately 5.7 and 0.5 mcg/mL, respectively. Oral administration with food slightly prolongs the time to peak concentration by approximately 1 hr and slightly decreases the peak concentration by approximately 14%. Therefore, levofloxacin can be administered without regard to food. The plasma concentration profile of levofloxacin after IV administration is similar and comparable in extent of exposure (AUC) to that observed for levofloxacin tablets when equal doses (mg/mg) are administered. Therefore, the oral and IV routes of administration can be considered interchangeable.
Distribution: The mean volume of distribution of levofloxacin generally ranges from 89-112 L after single and multiple 500-mg doses, indicating widespread distribution into body tissues. Penetration of levofloxacin into blister fluid is rapid and extensive. The blister fluid to plasma AUC ratio is approximately 1. Levofloxacin also penetrates well into lung tissues. Lung tissue concentrations were generally 2- to 5-fold higher than plasma concentrations and ranged from approximately 2.4-11.3 mcg/mL over a 24-hr period after a single dose of 500-mg oral dose. In vitro, over a clinically relevant range (1-10 mcg/mL) of serum/plasma levofloxacin concentrations, levofloxacin is approximately 24-38% bound to serum proteins across all species studied, as determined by the equilibrium dialysis method. Levofloxacin is mainly bound to serum albumin in humans. Levofloxacin binding to serum proteins is independent of the drug concentration.
Metabolism: Levofloxacin is stereochemically stable in plasma and urine and does not invert metabolically to its enantiomer, D-ofloxacin. Levofloxacin undergoes limited metabolism in humans and is primarily excreted as unchanged drug in urine. Following oral administration, approximately 87% of an administered dose was recovered as unchanged drug in urine within 48 hrs, whereas <4% of the dose was recovered in feces in 72 hrs. Less than 5% of an administered dose was recovered in the urine as the desmethyl and N-oxide metabolites, the only metabolites identified in humans. These metabolites have little relevant pharmacological activity.
Excretion: Levofloxacin is excreted largely as unchanged drug in the urine. The mean terminal plasma elimination half-life of levofloxacin ranges from approximately 6-8 hrs following single or multiple doses of levofloxacin given orally or IV. The mean apparent total body clearance and renal clearance range from approximately 144-226 mL/min and 95-142 mL/min, respectively. Renal clearance in excess of the glomerular filtration rate suggests that tubular secretion of levofloxacin occurs in addition to its glomerular filtration. Concomitant administration of either cimetidine or probenecid results in approximately 24% and 35% reduction in the levofloxacin renal clearance, respectively, indicating that secretion of levofloxacin occurs in the renal proximal tubule. No levofloxacin crystals were found in any of the urine samples freshly collected from subjects receiving levofloxacin.
Treatment of adults with mild, moderate and severe infections caused by susceptible strains of the designated microorganisms in the following conditions: Acute maxillary sinusitis, acute bacterial exacerbation of chronic bronchitis, community-acquired pneumonia, uncomplicated skin and skin structure infections, complicated urinary tract infections and acute pyelonephritis.
500 mg orally every 24 hrs.
Levofloxacin exhibits a low potential for acute toxicity. The patient should be observed and appropriate hydration maintained. Levofloxacin is not efficiently removed by hemodialysis or peritoneal dialysis.
History of hypersensitivity of levofloxacin, quinolone antimicrobial agents or any other components of Levobact.
Administer levofloxacin with caution in the presence of renal insufficiency. Careful clinical observations and appropriate laboratory studies should be performed prior to and during therapy since elimination of levofloxacin may be reduced. In patients with impaired renal function (creatinine clearance 80 mL/min), adjustment of the dosage regimen is necessary to avoid the accumulation of levofloxacin due to decreased clearance.
Quinolones may also cause increased intracranial pressure and central nervous system stimulation which may lead to tremors, restlessness, anxiety, lightheadedness, confusion, hallucinations, paranoia, depression, nightmares, insomnia and rarely suicidal thoughts or acts. If these reactions occur in patients receiving levofloxacin, Levobact should be discontinued and appropriate measures instituted.
Use in pregnancy & lactation: Levofloxacin should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus. Levofloxacin has not been measured in human milk. Based upon data from ofloxacin, it can be presumed that levofloxacin will be excreted in human milk. Because of the potential for serious adverse reactions from levofloxacin in nursing infants, a decision should be made whether to discontinue nursing or to discontinue Levobact, taking into account the importance of Levobact to the mother.
Levofloxacin should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus. Levofloxacin has not been measured in human milk. Based upon data from ofloxacin, it can be presumed that levofloxacin will be excreted in human milk. Because of the potential for serious adverse reactions from levofloxacin in nursing infants, a decision should be made whether to discontinue nursing or to discontinue Levobact, taking into account the importance of Levobact to the mother.
Diarrhea, nausea, vaginitis, flatulence, pruritus, rash, abdominal pain, genital moniliasis, dizziness, dyspepsia, insomnia, taste perversion, vomiting, anorexia, anxiety, constipation, edema, fatigue, headache, increased sweating, leukorrhea, malaise, nervousness, sleep disorders, tremors, urticaria.
Antacids, Sucralfate, Metal Cations, Multivitamins: While the chelation by divalent cations is less marked than other quinolones, concurrent administration of levofloxacin with antacids containing magnesium or aluminum, as well as sucralfate, metal cations eg, iron and multivitamin preparations with zinc, may interfere with the gastrointestinal absorption of levofloxacin resulting in systemic levels considerably lower than desired. These agents should be taken at least 2 hrs before or 2 hrs after levofloxacin administration.
Theophylline: Theophylline levels should be closely monitored and appropriate dosage adjustments made when levofloxacin is co-administered. Adverse reactions, including seizures, may occur with or without an elevation in serum theophylline levels.
Nonsteroidal Anti-inflammatory Drugs: The concomitant administration of a nonsteroidal anti-inflammatory drug with a quinolone, including levofloxacin, may increase the risk of CNS stimulation and convulsive seizures.
Antidiabetic Agents: Disturbances of blood glucose, including hyperglycemia and hypoglycemia, have been reported in patients treated concomitantly with quinolones and an antidiabetic agent. Therefore, careful monitoring of blood glucose is recommended when these agents are co-administered.
J01MA12 - levofloxacin ; Belongs to the class of fluoroquinolones. Used in the systemic treatment of infections.
FC tab 250 mg x 5's. 500 mg x 5's.