Левофлоксацин

Levofloxacin, the optically active S-isomer of the fluoroquinolone antibiotic ofloxacin, is two to four times more potent than ofloxacin with reportedly less side effects in treating infections of the lower respiratory and urinary tract, prostate infections and sexually transmitted diseases. It has broad and potent antibacterial activity over common Grampositive and -negative aerobic pathogens and obligate anaerobes. Different from the cephem antibiotics, levofloxacin is unique in its marked selectivity against members of the family Enterobacteriaceae and its negligible effect on predominant anaerobes. Levofloxacin also exhibits satisfactory antimicrobial effects in surgical infections and it may be used for treatment of gastrointestinal infections such as traveler’s diarrhea associated with the pathogenic Enterobacteriaceae.

Slight yellow powder

Antibacterial.

Levofloxacin is the active component of ofloxacin; d-ofloxacin is without significant antibacterial activity. It exhibits good activity in vitro against Gram-positive cocci (including Str. pneumoniae), Enterobacteriaceae, some fastidious Gram-negative bacilli and Ps. aeruginosa as well as chlamydiae, Mycoplasma pneumoniae, L. pneumophila and M. tuberculosis. MICs for Acinetobacter spp. and Sten. maltophilia are 0.06–0.25 and 0.5–2.0 mg/L, respectively. Activity against anaerobes is moderate to low.

Chemical structure: quinolone

For molecular weight and structure, see ofloxacin . Levofloxacin is the l-isomer of ofloxacin.

Oral absorption: >95%
C_max 500 mg oral: c. 5 mg/L after 1.5–2 h
750 mg oral: c. 8 mg/L after 1.5–2 h
500 mg intravenous (90-min infusion): c. 6 mg/L end infusion
750 mg intravenous (90-min infusion) ：c. 12 mg/L end infusion
Plasma half-life ：6–8 h
Volume of distribution：0.6–0.8 L/kg
Plasma protein binding： <25%
Co-administration with antacids, calcium, sucralfate and heavy metals decreases bioavailability and AUC. No interactions with warfarin or theophylline have been observed. Co-administration of a non-steroidal anti-inflammatory drug may increase the risk of convulsions. It undergoes limited metabolism and is primarily eliminated unchanged in urine by both glomerular filtration and tubular secretion. The free AUC:MIC ratio for Str. pneumoniae increases from about 55 to 70 when the daily dosage is raised from 500 mg to 750 mg.
It is stable in plasma and does not revert to d-ofloxacin. It undergoes limited metabolism and is primarily eliminated unchanged in the urine. Renal clearance in excess of the glomerular filtration rate suggests that tubular secretion also occurs. Concomitant administration of either cimetidine or probenecid reduces renal clearance by approximately onethird. Clearance is reduced and half-life is prolonged in patients with impaired renal function (creatinine clearance <50 mL/min) requiring dosage adjustment in such patients.

Acute bacterial sinusitis
Acute bacterial exacerbations of chronic bronchitis, community-acquired pneumonia
Uncomplicated and complicated skin and skin structure infections
Uncomplicated and complicated urinary infections including acute pyelonephritis
Chronic bacterial prostatitis

Side effects have been reported in 6–7% of patients and include fever, rash and other events common to the group. Elderly patients are at increased risk of developing severe tendon disorders including rupture, a risk increased by concomitant corticosteroid therapy.