Pharmacokinetics in healthy volunteers

In 6 fasting healthy male volunteers, approximately 95% to 98% of a single oral dose of lomefloxacin was absorbed. Absorption was rapid following single doses of 200 and 400 mg (Tmax 0.8 to 1.4 hours). Mean plasma concentration increased proportionally between 100 and 400 mg as shown below:

In 6 healthy male volunteers administered 400 mg of lomefloxacin on an empty stomach qd for 7 days, the following mean pharmacokinetic parameter values were obtained:

The elimination half-life in 8 subjects with normal renal function was approximately 8 hours. At 24 hours postdose, subjects with normal renal function receiving single doses of 200 or 400 mg had mean plasma lomefloxacin concentrations of 0.10 and 0.24 µg/mL, respectively. Steady-state concentrations were achieved within 48 hours of initiating therapy with one-a-day dosing. There was no drug accumulation with single-daily dosing in patients with normal renal function.

Approximately 65% of an orally administered dose was excreted in the urine as unchanged drug in patients with normal renal function. Following a 400-mg dose of lomefloxacin administered qd for 7 days, the mean urine concentration 4 hours postdose was in excess of 300 µg/mL. The mean urine concentration exceeded 35 µg/mL for at least 24 hours after dosing.

Following a single 400-mg dose, the solubility of lomefloxacin in urine usually exceeded its peak urinary concentration 2- to 6-fold. In this study, urine pH affected the solubility of lomefloxacin with solubilities ranging from 7.8 mg/mL at pH 5.2, to 2.4 mg/mL at pH 6.5, and 3.03 mg/mL at pH 8.12.

The urinary excretion of lomefloxacin was virtually complete within 72 hours after cessation of dosing, with approximately 65% of the dose being recovered as parent drug and 9% as its glucuronide metabolite. The mean renal clearance was 145 mL/min in subjects with normal renal function (GFR = 120 mL/min). This may indicate tubular secretion.

Food effect

When lomefloxacin and food were administered concomitantly, the rate of drug absorption was delayed (Tmax increased to 2 hours [delayed by 41%], Cmax decreased by 18%), and the extent of absorption (AUC) was decreased by 12%.

Pharmacokinetics in the geriatric population

In 16 healthy elderly volunteers (61 to 76 years of age) with normal renal function for their age, the half-life of lomefloxacin (mean of 8 hours) and its peak plasma concentration (mean of 4.2 µg/mL) following a single 400-mg dose were similar to those in 8 younger subjects dosed with a single 400-mg dose. Thus, drug absorption appears unaffected in the elderly. Plasma clearance was, however, reduced in this elderly population by approximately 25%, and the AUC was increased by approximately 33%. This slower elimination most likely reflects the decreased renal function normally observed in the geriatric population.

Pharmacokinetics in renally impaired patients

In 8 patients with creatinine clearance (ClCr) between 10 and 40 mL/min/1.73 m2, the mean AUC after a single 400-mg dose of lomefloxacin increased 335% over the AUC demonstrated in patients with a ClCr> 80 mL/min/1.73 m2. Also, in these patients, the mean t1/2 increased to 21 hours. In 8 patients with ClCr< 10 mL/min/1.73 m2, the mean AUC after a single 400-mg dose of lomefloxacin increased 700% over the AUC demonstrated in patients with a ClCr> 80 mL/min/1.73 m2. In these patients with ClCr< 10 mL/min/1.73 m2, the mean t1/2 increased to 45 hours. The plasma clearance of lomefloxacin was closely correlated with creatinine clearance, ranging from 31 mL/min/1.73 m2 when creatinine clearance was zero to 271 mL/min/1.73 m2 at a normal creatinine clearance of 110 mL/min/1.73 m2. Peak lomefloxacin concentrations were not affected by the degree of renal function when single doses of lomefloxacin were administered. Adjustment of dosage schedules for patients with such decreases in renal function is warranted. (See Dosage and Administration.)

Pharmacokinetics in patients with cirrhosis

In 12 patients with histologically confirmed cirrhosis, no significant changes in rate or extent of lomefloxacin exposure (Cmax, Tmax, t1/2, or AUC) were observed when they were administered 400 mg of lomefloxacin as a single dose. No data are available in cirrhotic patients treated with multiple doses of lomefloxacin. Cirrhosis does not appear to reduce the nonrenal clearance of lomefloxacin. There does not appear to be a need for a dosage reduction in cirrhotic patients, provided adequate renal function is present.

Metabolism and pharmacodynamics of lomefloxacin

Lomefloxacin is minimally metabolized although 5 metabolites have been identified in human urine. The glucuronide metabolite is found in the highest concentration and accounts for approximately 9% of the administered dose. The other 4 metabolites together account for < 0.5% of the dose.

Approximately 10% of an oral dose was recovered as unchanged drug in the feces.

Serum protein binding of lomefloxacin is approximately 10%.

The following are mean tissue- or fluid-to-plasma ratios of lomefloxacin following oral administration. Studies have not been conducted to assess the penetration of lomefloxacin into human cerebrospinal fluid.

In two studies including 74 healthy volunteers, the minimal dose of UVA light needed to cause erythema (MED-UVA) was inversely proportional to plasma lomefloxacin concentration. The MED-UVA values (16 hours and 12 hours postdose) were significantly higher than the MED-UVA values 2 hours postdose at steady state. Increasing the interval between lomefloxacin dosing and exposure to UVA light increased the amount of light energy needed for photoreaction. In a study of 27 healthy volunteers, the steady state AUC values and Cmin values were equivalent whether the drug was administered in the morning or in the evening.

Microbiology

Lomefloxacin is a bactericidal agent with in vitro activity against a wide range of gram-negative and gram-positive organisms. The bactericidal action of lomefloxacin results from interference with the activity of the bacterial enzyme DNA gyrase, which is needed for the transcription and replication of bacterial DNA. The minimum bactericidal concentration (MBC) generally does not exceed the minimum inhibitory concentration (MIC) by more than a factor of 2, except for staphylococci, which usually have MBCs 2 to 4 times the MIC.

Lomefloxacin has been shown to be active against most strains of the following organisms both in vitro and in clinical infections: (See Indications and Usage.)

Gram-positive aerobes

 

Staphylococcus saprophyticus

Gram-negative aerobes

 

Citrobacter diversus

 

Enterobacter cloacae

 

Escherichia coli

 

Haemophilus influenzae

 

Klebsiella pneumoniae

 

Moraxella catarrhalis

 

Proteus mirabilis

 

Pseudomonas aeruginosa (urinary tract only—See Indications and Usage and Warnings)

The following in vitro data are available; however, their clinical significance is unknown.

Lomefloxacin exhibits in vitro MICs of 2 µg/mL or less against most strains of the following organisms; however, the safety and effectiveness of lomefloxacin in treating clinical infections due to these organisms have not been established in adequate and well-controlled trials:

Gram-positive aerobes

 

Staphylococcus aureus (including methicillin-resistant strains)

 

Staphylococcus epidermidis (including methicillin-resistant strains)

Gram-negative aerobes

 

Aeromonas hydrophila

 

Citrobacter freundii

 

Enterobacter aerogenes

 

Enterobacter agglomerans

 

Haemophilus parainfluenzae

 

Hafnia alvei

 

Klebsiella oxytoca

 

Klebsiella ozaenae

 

Morganella morganii

 

Proteus vulgaris

 

Providencia alcalifaciens

 

Providencia rettgeri

 

Serratia liquefaciens

 

Serratia marcescens

Other organisms

 

Legionella pneumophila

Beta-lactamase production should have no effect on the in vitro activity of lomefloxacin.

Most group A, B, D, and G streptococci, Streptococcus pneumoniae, Pseudomonas cepacia, Ureaplasma urealyticum, Mycoplasma hominis, and anaerobic bacteria are resistant to lomefloxacin.

Lomefloxacin appears slightly less active in vitro when tested at acidic pH. An increase in inoculum size has little effect on the in vitro activity of lomefloxacin. In vitro resistance to lomefloxacin develops slowly (multiple-step mutation). Rapid one-step development of resistance occurs only rarely (< 10–9) in vitro.

Cross-resistance between lomefloxacin and other quinolone-class antimicrobial agents has been reported; however, cross-resistance between lomefloxacin and members of other classes of antimicrobial agents, such as aminoglycosides, penicillins, tetracyclines, cephalosporins, or sulfonamides has not yet been reported. Lomefloxacin is active in vitro against some strains of cephalosporin- and aminoglycoside-resistant gram-negative bacteria.

Treatment

Maxaquin (lomefloxacin HCl) film-coated tablets are indicated for the treatment of adults with mild to moderate infections caused by susceptible strains of the designated microorganisms in the conditions listed below: (See Dosage and Administration for specific dosing recommendations.)

Prevention / prophylaxis

Maxaquin is indicated preoperatively for the prevention of infection in the following situations:

• Transrectal prostate biopsy: to reduce the incidence of urinary tract infection, in the early and late postoperative periods (3–5 days and 3–4 weeks postsurgery).
• Transurethral surgical procedures: to reduce the incidence of urinary tract infection in the early postoperative period (3–5 days postsurgery).

Efficacy in decreasing the incidence of infections other than urinary tract infection has not been established. Maxaquin, like all drugs for prophylaxis of transurethral surgical procedures, usually should not be used in minor urologic procedures for which prophylaxis is not indicated (eg, simple cystoscopy or retrograde pyelography). (See Dosage and Administration.)

To reduce the development of drug-resistant bacteria and maintain the effectiveness of Maxaquin and other antibacterial drugs, Maxaquin should be used only to treat or prevent infections that are proven or strongly suspected to be caused by susceptible bacteria. When culture and susceptibility information are available, they should be considered in selecting or modifying antibacterial therapy. In the absence of such data, local epidemiology and susceptibility patterns may contribute to the empiric selection of therapy.

QT interval prolongation/torsades de pointes

Rare cases of torsades de pointes have been spontaneously reported during post-marketing surveillance in patients receiving quinolones, including lomefloxacin. These rare cases were associated with one or more of the following factors: age over 60, female gender, underlying cardiac disease, and/or use of multiple medications. Lomefloxacin should be avoided in patients with known prolongation of the QT interval, patients with uncorrected hypokalemia, and patients receiving class IA (quinidine, procainamide), or class III (amiodarone, sotalol) antiarrhythmic agents.

Peripheral neuropathy

Rare cases of sensory or sensorimotor axonal polyneuropathy affecting small and/or large axons resulting in paresthesias, hypoesthesias, dysesthesias and weakness have been reported in patients receiving quinolones, including lomefloxacin. Lomefloxacin should be discontinued if the patient experiences symptoms of neuropathy including pain, burning, tingling, numbness, and/or weakness, or is found to have deficits in light touch, pain, temperature, position sense, vibratory sensation, and/or motor strength in order to prevent the development of an irreversible condition.

Tendon effects

Ruptures of the shoulder, hand, Achilles tendon or other tendons that required surgical repair or resulted in prolonged disability have been reported in patients receiving quinolones, including lomefloxacin. Postmarketing surveillance reports indicate that this risk may be increased in patients receiving concomitant corticosteroids, especially the elderly. Lomefloxacin should be discontinued if the patient experiences pain, inflammation, or rupture of a tendon. Patients should rest and refrain from exercise until the diagnosis of tendonitis or tendon rupture has been excluded. Tendon rupture can occur during or after therapy with quinolones, including lomefloxacin.

General

Alteration of the dosage regimen is recommended for patients with impairment of renal function (ClCr< 40 mL/min/1.73 m2). (See Dosage and Administration.)

Prescribing Maxaquin in the absence of a proven or strongly suspected bacterial infection or a prophylactic indication is unlikely to provide benefit to the patient and increases the risk of the development of drug-resistant bacteria.

Information for patients

Patients should be advised

• to avoid to the maximum extent possible direct or indirect sunlight (including exposure through glass and exposure through sunscreens and sunblocks) and artificial ultraviolet light (eg sunlamps) during treatment with lomefloxacin and for several days after therapy;
• that they may reduce the risk of developing phototoxicity from sunlight by taking the daily dose of lomefloxacin at least 12 hours before exposure to the sun (eg in the evening);
• to discontinue lomefloxacin therapy at the first signs or symptoms of phototoxicity reaction such as a sensation of skin burning, redness, swelling, blisters, rash, itching, or dermatitis;
• that a patient who has experienced a phototoxic reaction should avoid re-exposure to sunlight and artificial ultraviolet light until he has completely recovered from the reaction. In rare cases, reactions have recurred up to several weeks after stopping lomefloxacin therapy.
• to drink fluids liberally;
• that lomefloxacin can be taken without regard to meals;
• that mineral supplements or vitamins with iron or minerals should not be taken within the 2-hour period before or after taking lomefloxacin (see Drug Interactions);
• that sucralfate and antacids containing magnesium or aluminum, or Videx® (didanosine), chewable/buffered tablets or the pediatric powder for oral solution should not be taken within 4 hours before or 2 hours after taking lomefloxacin. (See PRECAUTIONS — Drug Interactions.)
• that lomefloxacin can cause dizziness and lightheadedness and, therefore, patients should know how they react to lomefloxacin before they operate an automobile or machinery or engage in activities requiring mental alertness and coordination;
• to discontinue treatment and inform their physician if they experience pain, inflammation, or rupture of a tendon, and to rest and refrain from exercise until the diagnosis of tendinitis or tendon rupture has been confidently excluded;
• that lomefloxacin may be associated with hypersensitivity reactions, even following the first dose, and to discontinue the drug at the first sign of a skin rash or other allergic reaction;
• that convulsions have been reported in patients taking quinolones, including lomefloxacin, and to notify their physician before taking this drug if there is a history of this condition.
• that antibacterial drugs including Maxaquin should only be used to treat bacterial infections. They do not treat viral infections (e.g., the common cold). When Maxaquin is prescribed to treat a bacterial infection, patients should be told that although it is common to feel better early in the course of therapy, the medication should be taken exactly as directed. Skipping doses or not completing the full course of therapy may (1) decrease the effectiveness of the immediate treatment and (2) increase the likelihood that bacteria will develop resistance and will not be treatable by Maxaquin or other antibacterial drugs in the future.

Drug interactions

Carcinogenesis, mutagenesis, impairment of fertility

Pregnancy

Nursing mothers

It is not known whether lomefloxacin is excreted in human milk. However, it is known that other drugs of this class are excreted in human milk and that lomefloxacin is excreted in the milk of lactating rats. Because of the potential for serious adverse reactions from lomefloxacin in nursing infants, a decision should be made whether to discontinue nursing or to discontinue the drug, taking into account the importance of the drug to the mother.

Pediatric use

The safety and effectiveness of lomefloxacin in pediatric patients and adolescents less than 18 years of age have not been established. Lomefloxacin causes arthropathy in juvenile animals of several species. (See Warnings and Animal Pharmacology.)

Geriatric use

Of the total number of subjects in clinical studies of lomefloxacin, 25% were ≥ 65 years and 9% were ≥ 75 years. No overall differences in safety or effectiveness were observed between these subjects and younger subjects, and other reported clinical experience has not identified differences in responses between the elderly and younger patients, but greater sensitivity of some older individuals cannot be ruled out.

This drug is known to be substantially excreted by the kidney, and the risk of toxic reactions to this drug may be greater in patients with impaired renal function. Because elderly patients are more likely to have decreased renal function, care should be taken in dose selection, and it may be useful to monitor renal function. (See Clinical Pharmacology — Pharmacokinetics in the geriatric population.)

Adverse clinical events

The events with the highest incidence (≥ 1%) in patients, regardless of relationship to drug, were headache (3.6%), nausea (3.5%), photosensitivity (2.3%) [see Warnings], dizziness (2.1%), diarrhea (1.4%), and abdominal pain (1.2%).

Additional clinical events reported in < 1% of patients treated with Maxaquin, regardless of relationship to drug, are listed below:

Autonomic: increased sweating, dry mouth, flushing, syncope.

Body as a whole: fatigue, back pain, malaise, asthenia, chest pain, face edema, hot flashes, influenza-like symptoms, edema, chills, allergic reaction, anaphylactoid reaction, decreased heat tolerance.

Cardiovascular: tachycardia, hypertension, hypotension, myocardial infarction, angina pectoris, cardiac failure, bradycardia, arrhythmia, phlebitis, pulmonary embolism, extrasystoles, cerebrovascular disorder, cyanosis, cardiomyopathy.

Central and peripheral nervous system: tremor, vertigo, paresthesias, twitching, hypertonia, convulsions, hyperkinesia, coma.

Gastrointestinal: dyspepsia, vomiting, flatulence, constipation, gastrointestinal bleeding, dysphagia, stomatitis, tongue discoloration, gastrointestinal inflammation.

Hearing: earache, tinnitus.

Hematologic: purpura, lymphadenopathy, thrombocythemia, anemia, thrombocytopenia, increased fibrinolysis.

Hepatic: abnormal liver function.

Metabolic: thirst, hyperglycemia, hypoglycemia, gout.

Musculoskeletal: arthralgia, myalgia, leg cramps.

Ophthalmologic: abnormal vision, conjunctivitis, photophobia, eye pain, abnormal lacrimation.

Psychiatric: insomnia, nervousness, somnolence, anorexia, depression, confusion, agitation, increased appetite, depersonalization, paranoid reaction, anxiety, paroniria, abnormal thinking, concentration impairment.

Reproductive system: Female: vaginal moniliasis, vaginitis, leukorrhea, menstrual disorder, perineal pain, intermenstrual bleeding. Male: epididymitis, orchitis.

Resistance mechanism: viral infection, moniliasis, fungal infection.

Respiratory: respiratory infection, rhinitis, pharyngitis, dyspnea, cough, epistaxis, bronchospasm, respiratory disorder, increased sputum, stridor, respiratory depression.

Skin/Allergic: pruritus, rash, urticaria, skin exfoliation, bullous eruption, eczema, skin disorder, acne, skin discoloration, skin ulceration, angioedema. (See also Body as a whole.)

Special senses: taste perversion.

Urinary: hematuria, micturition disorder, dysuria, strangury, anuria.

Adverse laboratory events

Changes in laboratory parameters, listed as adverse events, without regard to drug relationship include:

Hematologic: monocytosis (0.2%), eosinophilia (0.1%), leukopenia (0.1%), leukocytosis (0.1%).

Renal: elevated BUN (0.1%), decreased potassium (0.1%), increased creatinine (0.1%).

Hepatic: elevations of ALT (SGPT) (0.4%), AST (SGOT) (0.3%), bilirubin (0.1%), alkaline phosphatase (0.1%).

Additional laboratory changes occurring in < 0.1% in the clinical studies included: elevation of serum gamma glutamyl transferase, decrease in total protein or albumin, prolongation of prothrombin time, anemia, decrease in hemoglobin, thrombocythemia, thrombocytopenia, abnormalities of urine specific gravity or serum electrolytes, increased albumin, elevated ESR, albuminuria, macrocytosis.

Treatment

Prevention / prophylaxis

The recommended dose of Maxaquin is described in the following chart:

STUDIES 1, 2, AND 3

STUDY 4

In a controlled clinical study of uncomplicated cystitis performed in Sweden, lomefloxacin 3-day treatment was compared with lomefloxacin 7-day treatment and norfloxacin 7-day treatment. In this study, using very strict evaluability criteria and microbiological criteria at 5–9 days post-therapy follow-up, the following bacterial eradication outcomes were obtained: