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Avelox (Moxifloxacin Hydrochloride) - Description and Clinical Pharmacology

 
 



To reduce the development of drug-resistant bacteria and maintain the effectiveness of AVELOX and other antibacterial drugs, AVELOX should be used only to treat or prevent infections that are proven or strongly suspected to be caused by bacteria.

DESCRIPTION

AVELOX (moxifloxacin hydrochloride) is a synthetic broad spectrum antibacterial agent and is available as AVELOX Tablets for oral administration and as AVELOX I.V. for intravenous administration. Moxifloxacin, a fluoroquinolone, is available as the monohydrochloride salt of 1-cyclopropyl-7-[(S,S)-2,8-diazabicyclo[4.3.0]non-8-yl]-6-fluoro-8-methoxy-1,4-dihydro-4-oxo-3 quinoline carboxylic acid. It is a slightly yellow to yellow crystalline substance with a molecular weight of 437.9. Its empirical formula is C21H24FN3O4*HCl and its chemical structure is as follows:

AVELOX Tablets are available as film-coated tablets containing moxifloxacin hydrochloride (equivalent to 400 mg moxifloxacin). The inactive ingredients are microcrystalline cellulose, lactose monohydrate, croscarmellose sodium, magnesium stearate, hypromellose, titanium dioxide, polyethylene glycol and ferric oxide.

AVELOX I.V. is available in ready-to-use 250 mL latex-free flexibags as a sterile, preservative free, 0.8% sodium chloride aqueous solution of moxifloxacin hydrochloride (containing 400 mg moxifloxacin) with pH ranging from 4.1 to 4.6. The appearance of the intravenous solution is yellow. The color does not affect, nor is it indicative of, product stability. The inactive ingredients are sodium chloride, USP, Water for Injection, USP, and may include hydrochloric acid and/or sodium hydroxide for pH adjustment. AVELOX I.V. contains approximately 34.2 mEq (787 mg) of sodium in 250 mL.

CLINICAL PHARMACOLOGY

Absorption

Moxifloxacin, given as an oral tablet, is well absorbed from the gastrointestinal tract. The absolute bioavailability of moxifloxacin is approximately 90 percent. Co-administration with a high fat meal (i.e., 500 calories from fat) does not affect the absorption of moxifloxacin.

Consumption of 1 cup of yogurt with moxifloxacin does not significantly affect the extent or rate of systemic absorption (AUC).

The mean (± SD) Cmax and AUC values following single and multiple doses of 400 mg moxifloxacin given orally are summarized below.

Cmax
(mg/L)
AUC
(mg•h/L)
Half-life
(hr)
Single Dose Oral
  Healthy (n = 372)
3.1 ± 1 36.1 ± 9.1 11.5 - 15.6 1
Multiple Dose Oral
  Healthy young male/female (n = 15) 4.5 ± 0.5 48 ± 2.7 12.7 ± 1.9
  Healthy elderly male (n = 8) 3.8 ± 0.3 51.8 ± 6.7
  Healthy elderly female (n = 8) 4.6 ± 0.6 54.6 ± 6.7
  Healthy young male (n = 8) 3.6 ± 0.5 48.2 ± 9
  Healthy young female (n = 9) 4.2 ± 0.5 49.3 ± 9.5

1 Range of means from different studies

The mean (± SD) Cmax and AUC values following single and multiple doses of 400 mg moxifloxacin given by 1 hour I.V. infusion are summarized below.

Cmax
(mg/L)
AUC
(mg•h/L)
Half-life
(hr)
Plasma concentrations increase proportionately with dose up to the highest dose tested (1200 mg single oral dose). The mean (± SD) elimination half-life from plasma is 12 ± 1.3 hours; steady-state is achieved after at least three days with a 400 mg once daily regimen.
Single Dose I.V.
  Healthy young male/female (n = 56) 3.9 ± 0.9 39.3 ± 8.6 8.2 - 15.4 1
  Patients (n = 118)
    Male (n = 64) 4.4 ± 3.7
    Female (n = 54) 4.5 ± 2
    < 65 years (n = 58) 4.6 ± 4.2
    ≥ 65 years (n = 60) 4.3 ± 1.3
Multiple Dose I.V.
  Healthy young male (n = 8) 4.2 ± 0.8 38 ± 4.7 14.8 ± 2.2
  Healthy elderly (n =12; 8 male, 4 female) 6.1 ± 1.3 48.2 ± 0.9 10.1 ± 1.6
  Patients 2 (n = 107)
    Male (n = 58) 4.2 ± 2.6
    Female (n = 49) 4.6 ± 1.5
    <65 years (n = 52) 4.1 ± 1.4
    ≥65 years (n = 55) 4.7 ± 2.7

1 Range of means from different studies
2 Expected Cmax (concentration obtained around the time of the end of the infusion)

Mean Steady-State Plasma Concentrations of Moxifloxacin Obtained With Once Daily Dosing of 400 mg Either Orally (n=10) or by I.V. Infusion (n=12)

Mean Steady-State Plasma Concentrations of Moxifloxacin Obtained With Once Daily Dosing of 400 mg Either Orally (n=10) or by I.V. Infusion (n=12)

Distribution

Moxifloxacin is approximately 30-50% bound to serum proteins, independent of drug concentration. The volume of distribution of moxifloxacin ranges from 1.7 to 2.7 L/kg. Moxifloxacin is widely distributed throughout the body, with tissue concentrations often exceeding plasma concentrations. Moxifloxacin has been detected in the saliva, nasal and bronchial secretions, mucosa of the sinuses, skin blister fluid, subcutaneous tissue, skeletal muscle, and abdominal tissues and fluids following oral or intravenous administration of 400 mg. Moxifloxacin concentrations measured post-dose in various tissues and fluids following a 400 mg oral or I.V. dose are summarized in the following table. The rates of elimination of moxifloxacin from tissues generally parallel the elimination from plasma.

Moxifloxacin Concentrations (mean ± SD) in Tissues and the Corresponding Plasma Concentrations After a Single 400 mg Oral or Intravenous Dose 1  
Tissue or Fluid N Plasma
Concentration
(µg/mL)
Tissue or Fluid
Concentration
(µg/mL or µg/g)
Tissue
Plasma
Ratio
Respiratory
Alveolar Macrophages 5 3.3 ± 0.7 61.8 ± 27.3 21.2 ± 10
Bronchial Mucosa 8 3.3 ± 0.7 5.5 ± 1.3 1.7 ± 0.3
Epithelial Lining Fluid 5 3.3 ± 0.7 24.4 ± 14.7 8.7 ± 6.1
Sinus
Maxillary Sinus Mucosa 4 3.7 ± 1.1 2 7.6 ± 1.7 2 ± 0.3
Anterior Ethmoid Mucosa 3 3.7 ± 1.1 8.8 ± 4.3 2.2 ± 0.6
Nasal Polyps 4 3.7 ± 1.1 9.8 ± 4.5 2.6 ± 0.6
Skin, Musculoskeletal
Blister Fluid 5 3 ± 0.5 3 2.6 ± 0.9 0.9 ± 0.2
Subcutaneous Tissue 6 2.3 ± 0.4 4 0.9 ± 0.3 5 0.4 ± 0.6
Skeletal Muscle 6 2.3 ± 0.4 0.9 ± 0.2 0.4 ± 0.1
Intra-Abdominal
Abdominal tissue 8 2.9 ± 0.5 7.6 ± 2 2.7 ± 0.8
Abdominal exudate 10 2.3 ± 0.5 3.5 ±1.2 1.6 ± 0.7
Abscess fluid 6 2.7 ± 0.7 2.3 ±1.5 0.8±0.4

1 all moxifloxacin concentrations were measured 3 hours after a single 400 mg dose, except the abdominal tissue and exudate concentrations which were measured at 2 hours post-dose and the sinus concentrations which were measured 3 hours post-dose after 5 days of dosing.
2 N = 5
3 N = 7
4 N = 12
5 Reflects only non-protein bound concentrations of drug.

Metabolism

Approximately 52% of an oral or intravenous dose of moxifloxacin is metabolized via glucuronide and sulfate conjugation. The cytochrome P450 system is not involved in moxifloxacin metabolism, and is not affected by moxifloxacin. The sulfate conjugate (M1) accounts for approximately 38% of the dose, and is eliminated primarily in the feces. Approximately 14% of an oral or intravenous dose is converted to a glucuronide conjugate (M2), which is excreted exclusively in the urine. Peak plasma concentrations of M2 are approximately 40% those of the parent drug, while plasma concentrations of M1 are generally less than 10% those of moxifloxacin.

In vitro studies with cytochrome (CYP) P450 enzymes indicate that moxifloxacin does not inhibit CYP3A4, CYP2D6, CYP2C9, CYP2C19, or CYP1A2, suggesting that moxifloxacin is unlikely to alter the pharmacokinetics of drugs metabolized by these enzymes.

Excretion

Approximately 45% of an oral or intravenous dose of moxifloxacin is excreted as unchanged drug (~20% in urine and ~25% in feces). A total of 96% ± 4% of an oral dose is excreted as either unchanged drug or known metabolites. The mean (± SD) apparent total body clearance and renal clearance are 12 ± 2 L/hr and 2.6 ± 0.5 L/hr, respectively.

Special Populations

Geriatric

Following oral administration of 400 mg moxifloxacin for 10 days in 16 elderly (8 male; 8 female) and 17 young (8 male; 9 female) healthy volunteers, there were no age-related changes in moxifloxacin pharmacokinetics. In 16 healthy male volunteers (8 young; 8 elderly) given a single 200 mg dose of oral moxifloxacin, the extent of systemic exposure (AUC and Cmax) was not statistically different between young and elderly males and elimination half-life was unchanged. No dosage adjustment is necessary based on age. In large phase III studies, the concentrations around the time of the end of the infusion in elderly patients following intravenous infusion of 400 mg were similar to those observed in young patients.

Pediatric

The pharmacokinetics of moxifloxacin in pediatric subjects have not been studied.

Gender

Following oral administration of 400 mg moxifloxacin daily for 10 days to 23 healthy males (19-75 years) and 24 healthy females (19-70 years), the mean AUC and Cmax were 8% and 16% higher, respectively, in females compared to males. There are no significant differences in moxifloxacin pharmacokinetics between male and female subjects when differences in body weight are taken into consideration.

A 400 mg single dose study was conducted in 18 young males and females. The comparison of moxifloxacin pharmacokinetics in this study (9 young females and 9 young males) showed no differences in AUC or Cmax due to gender. Dosage adjustments based on gender are not necessary.

Race

Steady-state moxifloxacin pharmacokinetics in male Japanese subjects were similar to those determined in Caucasians, with a mean Cmax of 4.1 µg/mL, an AUC24 of 47 µg•h/mL, and an elimination half-life of 14 hours, following 400 mg p.o. daily.

Renal Insufficiency

The pharmacokinetic parameters of moxifloxacin are not significantly altered in mild, moderate, severe, or end-stage renal disease. No dosage adjustment is necessary in patients with renal impairment, including those patients requiring hemodialysis (HD) or continuous ambulatory peritoneal dialysis (CAPD).

In a single oral dose study of 24 patients with varying degrees of renal function from normal to severely impaired, the mean peak concentrations (Cmax) of moxifloxacin were reduced by 21% and 28% in the patients with moderate (CLCR≥ 30 and ≤ 60 mL/min) and severe (CLCR<30 mL/min) renal impairment, respectively. The mean systemic exposure (AUC) in these patients was increased by 13%. In the moderate and severe renally impaired patients, the mean AUC for the sulfate conjugate (M1) increased by 1.7-fold (ranging up to 2.8-fold) and mean AUC and Cmax for the glucuronide conjugate (M2) increased by 2.8-fold (ranging up to 4.8-fold) and 1.4-fold (ranging up to 2.5-fold), respectively.

The pharmacokinetics of single dose and multiple dose moxifloxacin were studied in patients with CLCR< 20 mL/min on either hemodialysis or continuous ambulatory peritoneal dialysis (8 HD, 8 CAPD). Following a single 400 mg oral dose, the AUC of moxifloxacin in these HD and CAPD patients did not vary significantly from the AUC generally found in healthy volunteers. Cmax values of moxifloxacin were reduced by about 45% and 33% in HD and CAPD patients, respectively, compared to healthy, historical controls. The exposure (AUC) to the sulfate conjugate (M1) increased by 1.4- to 1.5-fold in these patients. The mean AUC of the glucuronide conjugate (M2) increased by a factor of 7.5, whereas the mean Cmax values of the glucuronide conjugate (M2) increased by a factor of 2.5 to 3, compared to healthy subjects. The sulfate and the glucuronide conjugates of moxifloxacin are not microbiologically active, and the clinical implication of increased exposure to these metabolites in patients with renal disease including those undergoing HD and CAPD has not been studied.

Oral administration of 400 mg QD moxifloxacin for 7 days to patients on HD or CAPD produced mean systemic exposure (AUCss) to moxifloxacin similar to that generally seen in healthy volunteers. Steady-state Cmax values were about 22% lower in HD patients but were comparable between CAPD patients and healthy volunteers. Both HD and CAPD removed only small amounts of moxifloxacin from the body (approximately 9% by HD, and 3% by CAPD). HD and CAPD also removed about 4% and 2% of the glucuronide metabolite (M2), respectively.

Hepatic Insufficiency

No dosage adjustment is recommended for mild, moderate, or severe hepatic insufficiency (Child-Pugh Classes A, B, or C). However, due to metabolic disturbances associated with hepatic insufficiency, which may lead to QT prolongation, moxifloxacin should be used with caution in these patients. (See WARNINGS and DOSAGE AND ADMINISTRATION.)

In 400 mg single oral dose studies in 6 patients with mild (Child-Pugh Class A) and 10 patients with moderate (Child-Pugh Class B) hepatic insufficiency, moxifloxacin mean systemic exposure (AUC) was 78% and 102%, respectively, of 18 healthy controls and mean peak concentration (Cmax)  was 79% and 84% of controls.

The mean AUC of the sulfate conjugate of moxifloxacin (M1) increased by 3.9-fold (ranging up to 5.9-fold) and 5.7-fold (ranging up to 8-fold) in the mild and moderate groups, respectively. The mean Cmax of M1 increased by approximately 3-fold in both groups (ranging up to 4.7- and 3.9-fold). The mean AUC of the glucuronide conjugate of moxifloxacin (M2) increased by 1.5-fold (ranging up to 2.5-fold) in both groups. The mean Cmax of M2 increased by 1.6- and 1.3-fold (ranging up to 2.7- and 2.1-fold), respectively. The clinical significance of increased exposure to the sulfate and glucuronide conjugates has not been studied. In a subset of patients participating in a clinical trial, the plasma concentrations of moxifloxacin and metabolites determined approximately at the moxifloxacin Tmax following the first intravenous or oral moxifloxacin dose in the Child-Pugh Class C patients (n=10) were similar to those in the Child-Pugh Class A/B patients (n=5), and also similar to those observed in healthy volunteer studies.

Photosensitivity Potential

A study of the skin response to ultraviolet (UVA and UVB) and visible radiation conducted in 32 healthy volunteers (8 per group) demonstrated that moxifloxacin does not show phototoxicity in comparison to placebo. The minimum erythematous dose (MED) was measured before and after treatment with moxifloxacin (200 mg or 400 mg once daily), lomefloxacin (400 mg once daily), or placebo. In this study, the MED measured for both doses of moxifloxacin were not significantly different from placebo, while lomefloxacin significantly lowered the MED. (See PRECAUTIONS, Information for Patients.)

It is difficult to ascribe relative photosensitivity/phototoxicity among various fluoroquinolones during actual patient use because other factors play a role in determining a subject's susceptibility to this adverse event such as: a patient's skin pigmentation, frequency and duration of sun and artificial ultraviolet light (UV) exposure, wearing of sunscreen and protective clothing, the use of other concomitant drugs and the dosage and duration of fluoroquinolone therapy (See ADVERSE REACTIONS and ADVERSE REACTIONS/Post-Marketing Adverse Event Reports).

Drug-drug Interactions

The potential for pharmacokinetic drug interactions between moxifloxacin and itraconazole, theophylline, warfarin, digoxin, atenolol, probenecid, morphine, oral contraceptives, ranitidine, glyburide, calcium, iron, and antacids has been evaluated. There was no clinically significant effect of moxifloxacin on itraconazole, theophylline, warfarin, digoxin, atenolol, oral contraceptives, or glyburide kinetics. Itraconazole, theophylline, warfarin, digoxin, probenecid, morphine, ranitidine, and calcium did not significantly affect the pharmacokinetics of moxifloxacin. These results and the data from in vitro studies suggest that moxifloxacin is unlikely to significantly alter the metabolic clearance of drugs metabolized by CYP3A4, CYP2D6, CYP2C9, CYP2C19, or CYP1A2 enzymes.

As with all other quinolones, iron and antacids significantly reduced bioavailability of moxifloxacin.

Itraconazole:

 In a study involving 11 healthy volunteers, there was no significant effect of itraconazole (200 mg once daily for 9 days), a potent inhibitor of cytochrome P4503A4, on the pharmacokinetics of moxifloxacin (a single 400 mg dose given on the 7th day of itraconazole dosing). In addition, moxifloxacin was shown not to affect the pharmacokinetics of itraconazole.

Theophylline:

 No significant effect of moxifloxacin (200 mg every twelve hours for 3 days) on the pharmacokinetics of theophylline (400 mg every twelve hours for 3 days) was detected in a study involving 12 healthy volunteers. In addition, theophylline was not shown to affect the pharmacokinetics of moxifloxacin. The effect of co-administration of a 400 mg dose of moxifloxacin with theophylline has not been studied, but it is not expected to be clinically significant based on in vitro metabolic data showing that moxifloxacin does not inhibit the CYP1A2 isoenzyme.

Warfarin:

 No significant effect of moxifloxacin (400 mg once daily for eight days) on the pharmacokinetics of R- and S-warfarin (25 mg single dose of warfarin sodium on the fifth day) was detected in a study involving 24 healthy volunteers. No significant change in prothrombin time was observed. (See PRECAUTIONS, Drug Interactions.)

Digoxin:

 No significant effect of moxifloxacin (400 mg once daily for two days) on digoxin (0.6 mg as a single dose) AUC was detected in a study involving 12 healthy volunteers. The mean digoxin Cmax increased by about 50% during the distribution phase of digoxin. This transient increase in digoxin Cmax is not viewed to be clinically significant. Moxifloxacin pharmacokinetics were similar in the presence or absence of digoxin. No dosage adjustment for moxifloxacin or digoxin is required when these drugs are administered concomitantly.

Atenolol:

 In a crossover study involving 24 healthy volunteers (12 male; 12 female), the mean atenolol AUC following a single oral dose of 50 mg atenolol with placebo was similar to that observed when atenolol was given concomitantly with a single 400 mg oral dose of moxifloxacin. The mean Cmax of single dose atenolol decreased by about 10% following co-administration with a single dose of moxifloxacin.

Morphine:

 No significant effect of morphine sulfate (a single 10 mg intramuscular dose) on the mean AUC and Cmax of moxifloxacin (400 mg single dose) was observed in a study of 20 healthy male and female volunteers.

Oral Contraceptives:

 A placebo-controlled study in 29 healthy female subjects showed that moxifloxacin 400 mg daily for 7 days did not interfere with the hormonal suppression of oral contraception with 0.15 mg levonorgestrel/0.03 mg ethinylestradiol (as measured by serum progesterone, FSH, estradiol, and LH), or with the pharmacokinetics of the administered contraceptive agents.

Probenecid:

 Probenecid (500 mg twice daily for two days) did not alter the renal clearance and total amount of moxifloxacin (400 mg single dose) excreted renally in a study of 12 healthy volunteers.

Ranitidine:

 No significant effect of ranitidine (150 mg twice daily for three days as pretreatment) on the pharmacokinetics of moxifloxacin (400 mg single dose) was detected in a study involving 10 healthy volunteers.

Antidiabetic agents:

In diabetics, glyburide (2.5 mg once daily for two weeks pretreatment and for five days concurrently) mean AUC and Cmax were 12% and 21% lower, respectively, when taken with moxifloxacin (400 mg once daily for five days) in comparison to placebo. Nonetheless, blood glucose levels were decreased slightly in patients taking glyburide and moxifloxacin in comparison to those taking glyburide alone, suggesting no interference by moxifloxacin on the activity of glyburide. These interaction results are not viewed as clinically significant.

Calcium:

 Twelve healthy volunteers were administered concomitant moxifloxacin (single 400 mg dose) and calcium (single dose of 500 mg Ca++ dietary supplement) followed by an additional two doses of calcium 12 and 24 hours after moxifloxacin administration. Calcium had no significant effect on the mean AUC of moxifloxacin. The mean Cmax was slightly reduced and the time to maximum plasma concentration was prolonged when moxifloxacin was given with calcium compared to when moxifloxacin was given alone (2.5 hours versus 0.9 hours). These differences are not considered to be clinically significant.

Antacids:

When moxifloxacin (single 400 mg tablet dose) was administered two hours before, concomitantly, or 4 hours after an aluminum/magnesium-containing antacid (900 mg aluminum hydroxide and 600 mg magnesium hydroxide as a single oral dose) to 12 healthy volunteers there was a 26%, 60% and 23% reduction in the mean AUC of moxifloxacin, respectively. Moxifloxacin should be taken at least 4 hours before or 8 hours after antacids containing magnesium or aluminum, as well as sucralfate, metal cations such as iron, and multivitamin preparations with zinc, or VIDEX® (didanosine) chewable/ buffered tablets or the pediatric powder for oral solution. (See PRECAUTIONS, Drug Interactions and DOSAGE AND ADMINISTRATION.)

Iron: When moxifloxacin tablets were administered concomitantly with iron (ferrous sulfate 100 mg once daily for two days), the mean AUC and Cmax of moxifloxacin was reduced by 39% and 59%, respectively. Moxifloxacin should only be taken more than 4 hours before or 8 hours after iron products. (See PRECAUTIONS, Drug Interactions and DOSAGE AND ADMINISTRATION.)

Electrocardiogram:

 Prolongation of the QT interval in the ECG has been observed in some patients receiving moxifloxacin. Following oral dosing with 400 mg of moxifloxacin the mean (± SD) change in QTc from the pre-dose value at the time of maximum drug concentration was 6 msec (± 26) (n = 787). Following a course of daily intravenous dosing (400 mg; 1 hour infusion each day) the mean change in QTc from the Day 1 pre-dose value was 9 msec (± 24) on Day 1 (n = 69) and 3 msec (± 29) on Day 3 (n = 290). (See WARNINGS.)

There is limited information available on the potential for a pharmacodynamic interaction in humans between moxifloxacin and other drugs that prolong the QTc interval of the electrocardiogram. Sotalol, a Class III antiarrhythmic, has been shown to further increase the QTc interval when combined with high doses of intravenous (I.V.) moxifloxacin in dogs. Therefore, moxifloxacin should be avoided with Class IA and Class III antiarrhythmics. (See ANIMAL PHARMACOLOGY, WARNINGS, and PRECAUTIONS.)

MICROBIOLOGY

Moxifloxacin has in vitro activity against a wide range of Gram-positive and Gram-negative microorganisms. The bactericidal action of moxifloxacin results from inhibition of the topoisomerase II (DNA gyrase) and topoisomerase IV required for bacterial DNA replication, transcription, repair, and recombination. It appears that the C8-methoxy moiety contributes to enhanced activity and lower selection of resistant mutants of Gram-positive bacteria compared to the C8-H moiety. The presence of the bulky bicycloamine substituent at the C-7 position prevents active efflux, associated with the NorA or pmrA genes seen in certain Gram-positive bacteria.

The mechanism of action for quinolones, including moxifloxacin, is different from that of macrolides, beta-lactams, aminoglycosides, or tetracyclines; therefore, microorganisms resistant to these classes of drugs may be susceptible to moxifloxacin and other quinolones. There is no known cross-resistance between moxifloxacin and other classes of antimicrobials.

In vitro resistance to moxifloxacin develops slowly via multiple-step mutations. Resistance to moxifloxacin occurs in vitro at a general frequency of between 1.8 x 10†“9 to < 1 x 10†“11 for Gram-positive bacteria.

Cross-resistance has been observed between moxifloxacin and other fluoroquinolones against Gram-negative bacteria. Gram-positive bacteria resistant to other fluoroquinolones may, however, still be susceptible to moxifloxacin.

Moxifloxacin has been shown to be active against most strains of the following microorganisms, both in vitro and in clinical infections as described in the INDICATIONS AND USAGE section.

Aerobic Gram-positive microorganisms

Enterococcus faecalis (many strains are only moderately susceptible)

Staphylococcus aureus (methicillin-susceptible strains only)

Streptococcus anginosus

Streptococcus constellatus

Streptococcus pneumoniae (including multi-drug resistant strains [MDRSP]*)

Streptococcus pyogenes

* MDRSP, Multi-drug resistant Streptococcus pneumoniae includes isolates previously known as PRSP (Penicillin-resistant S. pneumoniae), and are strains resistant to two or more of the following antibiotics: penicillin (MIC ≥ 2 µg/mL), 2nd generation cephalosporins (e.g., cefuroxime), macrolides, tetracyclines, and trimethoprim/sulfamethoxazole.

Aerobic Gram-negative microorganisms

Enterobacter cloacae

Escherichia coli

Haemophilus influenzae

Haemophilus parainfluenzae

Klebsiella pneumoniae

Moraxella catarrhalis

Proteus mirabilis

Anaerobic microorganisms

Bacteroides fragilis

Bacteroides thetaiotaomicron

Clostridium perfringens

Peptostreptococcus species

Other microorganisms

Chlamydia pneumoniae

Mycoplasma pneumoniae

The following in vitro data are available, but their clinical significance is unknown.
Moxifloxacin exhibits in vitro minimum inhibitory concentrations (MICs) of 2 µg/mL or less against most (≥ 90%) strains of the following microorganisms; however, the safety and effectiveness of moxifloxacin in treating clinical infections due to these microorganisms have not been established in adequate and well-controlled clinical trials.

Aerobic Gram-positive microorganisms

Staphylococcus epidermidis (methicillin-susceptible strains only)

Streptococcus agalactiae

Streptococcus viridans group

Aerobic Gram-negative microorganisms

Citrobacter freundii

Klebsiella oxytoca

Legionella pneumophila

Anaerobic microorganisms

Fusobacterium species

Prevotella species

Susceptibility Tests

Dilution Techniques: Quantitative methods are used to determine antimicrobial minimum inhibitory concentrations (MICs). These MICs provide estimates of the susceptibility of bacteria to antimicrobial compounds. The MICs should be determined using a standardized procedure. Standardized procedures are based on a dilution method1 (broth or agar) or equivalent with standardized inoculum concentrations and standardized concentrations of moxifloxacin powder. The MIC values should be interpreted according to the following criteria:

For testing Enterobacteriaceae and methicillin-susceptible Staphylococcus aureus:

MIC (µg/mL) Interpretation
≤ 2 Susceptible (S)
   4 Intermediate (I)
≥ 8 Resistant (R)

For testing Haemophilus influenzae and Haemophilus parainfluenzae a:

a This interpretive standard is applicable only to broth microdilution susceptibility tests with Haemophilus influenzae and Haemophilus parainfluenzae using Haemophilus Test Medium1.
MIC (µg/mL) Interpretation
≤ 1 Susceptible (S)

The current absence of data on resistant strains precludes defining any results other than "Susceptible". Strains yielding MIC results suggestive of a "nonsusceptible" category should be submitted to a reference laboratory for further testing.

For testing Streptococcus species including Streptococcus pneumoniae b and Enterococcus faecalis:

b These interpretive standards are applicable only to broth microdilution susceptibility tests using cation-adjusted Mueller-Hinton broth with 2 - 5% lysed horse blood.
MIC (µg/mL) Interpretation
≤ 1 Susceptible (S)
   2 Intermediate (I)
≥ 4 Resistant (R)

A report of "Susceptible" indicates that the pathogen is likely to be inhibited if the antimicrobial compound in the blood reaches the concentrations usually achievable. A report of "Intermediate" indicates that the result should be considered equivocal, and, if the microorganism is not fully susceptible to alternative, clinically feasible drugs, the test should be repeated. This category implies possible clinical applicability in body sites where the drug is physiologically concentrated or in situations where a high dosage of drug can be used. This category also provides a buffer zone which prevents small uncontrolled technical factors from causing major discrepancies in interpretation. A report of "Resistant" indicates that the pathogen is not likely to be inhibited if the antimicrobial compound in the blood reaches the concentrations usually achievable; other therapy should be selected.

Standardized susceptibility test procedures require the use of laboratory control microorganisms to control the technical aspects of the laboratory procedures. Standard moxifloxacin powder should provide the following MIC values:

c This quality control range is applicable to only H. influenzae ATCC 49247 tested by a broth microdilution procedure using Haemophilus Test Medium (HTM)1.
d This quality control range is applicable to only S. pneumoniae ATCC 49619 tested by a broth microdilution procedure using cation-adjusted Mueller-Hinton broth with 2 - 5% lysed horse blood.
Microorganism MIC (µg/mL)
Enterococcus faecalis ATCC 29212 0.06 - 0.5
Escherichia coli ATCC 25922 0.008 - 0.06
Haemophilus influenzae  ATCC 49247c 0.008 - 0.03
Staphylococcus aureus ATCC 29213 0.015 - 0.06
Streptococcus pneumoniae  ATCC 49619d 0.06 - 0.25

Diffusion Techniques: Quantitative methods that require measurement of zone diameters also provide reproducible estimates of the susceptibility of bacteria to antimicrobial compounds. One such standardized procedure2 requires the use of standardized inoculum concentrations. This procedure uses paper disks impregnated with 5-µg moxifloxacin to test the susceptibility of microorganisms to moxifloxacin.

Reports from the laboratory providing results of the standard single-disk susceptibility test with a 5-µg moxifloxacin disk should be interpreted according to the following criteria:

The following zone diameter interpretive criteria should be used for testing Enterobacteriaceae and methicillin-susceptible Staphylococcus aureus:

Zone Diameter (mm) Interpretation
≥ 19 Susceptible (S)
16 — 18 Intermediate (I)
≤ 15 Resistant (R)

For testing Haemophilus influenzae and Haemophilus parainfluenzae e:

eThis zone diameter standard is applicable only to tests with Haemophilus influenzae and Haemophilus parainfluenzae using Haemophilus Test Medium (HTM)2.
Zone Diameter (mm) Interpretation
≥ 18 Susceptible (S)

The current absence of data on resistant strains precludes defining any results other than "Susceptible". Strains yielding zone diameter results suggestive of a "nonsusceptible" category should be submitted to a reference laboratory for further testing.

For testing Streptococcus species including Streptococcus pneumoniae f and Enterococcus faecalis:

f These interpretive standards are applicable only to disk diffusion tests using Mueller-Hinton agar supplemented with 5% sheep blood incubated in 5% CO2.
Zone Diameter (mm) Interpretation
≥ 18 Susceptible (S)
15 — 17 Intermediate (I)
≤ 14 Resistant (R)

Interpretation should be as stated above for results using dilution techniques. Interpretation involves correlation of the diameter obtained in the disk test with the MIC for moxifloxacin.

As with standardized dilution techniques, diffusion methods require the use of laboratory control microorganisms that are used to control the technical aspects of the laboratory procedures. For the diffusion technique, the 5-µg moxifloxacin disk should provide the following zone diameters in these laboratory test quality control strains:

gThese quality control limits are applicable to only H. influenzae ATCC 49247 testing using Haemophilus Test Medium (HTM)2.
h These quality control limits are applicable only to tests conducted with S. pneumoniae ATCC 49619 tested by a disk diffusion procedure using Mueller-Hinton agar supplemented with 5% sheep blood and incubated in 5% CO2.
Microorganism Zone Diameter (mm)
Escherichia coli ATCC 25922 28 — 35
Haemophilus influenzae ATCC 49247g 31 — 39
Staphylococcus aureus ATCC 25923 28 — 35
Streptococcus pneumoniae ATCC 49619h 25 — 31

Anaerobic Techniques: For anaerobic bacteria, the susceptibility to moxifloxacin as MICs can be determined by standardized procedures3 such as reference agar dilution methodsi. The MICs obtained should be interpreted according to the following criteria:

i This interpretive standard is applicable to reference agar dilution susceptibility tests using Brucella agar supplemented with hemin, vitamin K1 and 5% laked sheep blood.
MIC (ug/mL) Interpretation
≤2 Susceptible (S)
4 Intermediate (I)
≥ 8 Resistant (R)

Acceptable ranges of MICs (ug/mL) for control strains for reference agar dilution testing j:

jThese quality control ranges are applicable to reference agar dilution tests using Brucella agar supplemented with hemin, vitamin K1 and 5% laked sheep blood.
Microorganism MIC (ug/mL)
Bacteroides fragilis ATCC 25285 0.12-0.5
Bacteroides thetaiotaomicron ATCC 29741 1-4
Eubacterium lentum ATCC 43055 0.12-0.5

ANIMAL PHARMACOLOGY

Quinolones have been shown to cause arthropathy in immature animals. In studies in juvenile dogs oral doses of moxifloxacin ≥ 30 mg/kg/day (approximately 1.5 times the maximum recommended human dose based upon systemic exposure) for 28 days resulted in arthropathy. There was no evidence of arthropathy in mature monkeys and rats at oral doses up to 135 and 500 mg/kg/day, respectively.

Unlike some other members of the quinolone class, crystalluria was not observed in 6 month repeat dose studies in rats and monkeys with moxifloxacin.

No ocular toxicity was observed in a 13 week oral repeat dose study in dogs with a moxifloxacin dose of 60 mg/kg/day. Ocular toxicity was not observed in 6 month repeat dose studies in rats and monkeys (daily oral doses up to 500 mg/kg and 135 mg/kg, respectively). In beagle dogs, electroretinographic (ERG) changes were observed in a 2 week study at oral doses of 60 and 90 mg/kg/day. Histopathological changes were observed in the retina from one of four dogs at 90 mg/kg/day, a dose associated with mortality in this study.

Some quinolones have been reported to have proconvulsant activity that is exacerbated with concomitant use of non-steroidal anti-inflammatory drugs (NSAIDs). Moxifloxacin at an oral dose of 300 mg/kg did not show an increase in acute toxicity or potential for CNS toxicity (e.g., seizures) in mice when used in combination with NSAIDs such as diclofenac, ibuprofen, or fenbufen.

In dog studies, at plasma concentrations about five times the human therapeutic level, a QT-prolonging effect of moxifloxacin was found. Electrophysiological in vitro studies suggested an inhibition of the rapid activating component of the delayed rectifier potassium current (IKr) as an underlying mechanism. In dogs, the combined infusion of sotalol, a Class III antiarrhythmic agent, with moxifloxacin induced a higher degree of QTc prolongation than that induced by the same dose (30 mg/kg) of moxifloxacin alone.

In a local tolerability study performed in dogs, no signs of local intolerability were seen when moxifloxacin was administered intravenously. After intra-arterial injection, inflammatory changes involving the peri-arterial soft tissue were observed suggesting that intra-arterial administration of moxifloxacin should be avoided.

CLINICAL STUDIES

Acute Bacterial Exacerbation of Chronic Bronchitis

AVELOX Tablets (400 mg once daily for five days) were evaluated for the treatment of acute bacterial exacerbation of chronic bronchitis in a large, randomized, double-blind, controlled clinical trial conducted in the US. This study compared AVELOX with clarithromycin (500 mg twice daily for 10 days) and enrolled 629 patients. The primary endpoint for this trial was clinical success at 7-17 days post-therapy. The clinical success for AVELOX was 89% (222/250) compared to 89% (224/251) for clarithromycin.

The following outcomes are the clinical success rates at the follow-up visit for the clinically evaluable patient groups by pathogen:

PATHOGEN AVELOX Clarithromycin
Streptococcus pneumoniae 16/16 (100%) 20/23 (87%)
Haemophilus influenzae 33/37 (89%) 36/41 (88%)
Haemophilus parainfluenzae 16/16 (100%) 14/14 (100%)
Moraxella catarrhalis 29/34 (85%) 24/24 (100%)
Staphylococcus aureus 15/16 (94%) 6/8 (75%)
Klebsiella pneumoniae 18/20 (90%) 10/11 (91%)

The microbiological eradication rates (eradication plus presumed eradication) in AVELOX treated patients were Streptococcus pneumoniae 100%, Haemophilus influenzae 89%, Haemophilus parainfluenzae 100%, Moraxella catarrhalis 85%, Staphylococcus aureus 94%, and Klebsiella pneumoniae 85%.

Community Acquired Pneumonia

A large, randomized, double-blind, controlled clinical trial was conducted in the US to compare the efficacy of AVELOX Tablets (400 mg once daily) to that of high-dose clarithromycin (500 mg twice daily) in the treatment of patients with clinically and radiologically documented community acquired pneumonia. This study enrolled 474 patients (382 of whom were valid for the primary efficacy analysis conducted at the 14 - 35 day follow-up visit). Clinical success for clinically evaluable patients was 95% (184/194) for AVELOX and 95% (178/188) for high dose clarithromycin.

A large, randomized, double-blind, controlled trial was conducted in the US and Canada to compare the efficacy of sequential IV/PO AVELOX 400 mg QD for 7-14 days to an IV/PO fluoroquinolone control (trovafloxacin or levofloxacin) in the treatment of patients with clinically and radiologically documented community acquired pneumonia. This study enrolled 516 patients, 362 of whom were valid for the primary efficacy analysis conducted at the 7-30 day post-therapy visit. The clinical success rate was 86% (157/182) for AVELOX therapy and 89% (161/180) for the fluoroquinolone comparators.

An open-label ex-US study that enrolled 628 patients compared AVELOX to sequential IV/PO amoxicillin/clavulanate (1.2 g IV q8h/625 mg PO q8h) with or without high-dose IV/PO clarithromycin (500 mg BID). The intravenous formulations of the comparators are not FDA approved. The clinical success rate at Day 5-7 (the primary efficacy timepoint) for AVELOX therapy was 93% (241/258) and demonstrated superiority to amoxicillin/clavulanate ± clarithromycin (85%, 239/280) [95% C.I. 2.9%, 13.2%]. The clinical success rate at the 21-28 days post-therapy visit for AVELOX was 84% (216/258), which also demonstrated superiority to the comparators (74%, 208/280) [95% C.I. 2.6%, 16.3%].

The clinical success rates by pathogen across four CAP studies are presented below:

Clinical Success Rates By Pathogen (Pooled CAP Studies)
PATHOGEN AVELOX
Streptococcus pneumoniae 80/85 (94%)
Staphylococcus aureus 17/20 (85%)
Klebsiella pneumoniae 11/12 (92%)
Haemophilus influenzae 56/61 (92%)
Chlamydia pneumoniae 119/128 (93%)
Mycoplasma pneumoniae 73/76 (96%)
Moraxella catarrhalis 11/12 (92%)

Community Acquired Pneumonia caused by Multi-Drug Resistant Streptococcus pneumoniae (MDRSP)*

Avelox was effective in the treatment of community acquired pneumonia (CAP) caused by multi-drug resistant Streptococcus pneumoniae MDRSP* isolates. Of 37 microbiologically evaluable patients with MDRSP isolates, 35 patients (95%) achieved clinical and bacteriological success post-therapy. The clinical and bacteriological success rates based on the number of patients treated are shown in the table below.

* MDRSP, Multi-drug resistant Streptococcus pneumoniae includes isolates previously known as PRSP (Penicillin-resistant S. pneumoniae), and are strains resistant to two or more of the following antibiotics: penicillin (MIC ≥ 2 µg/mL), 2nd generation cephalosporins (e.g., cefuroxime), macrolides, tetracyclines, and trimethoprim/sulfamethoxazole.

Clinical and Bacteriological Success Rates for Moxifloxacin-Treated MDRSP CAP Patients (Population: Valid for Efficacy):
Screening Susceptibility Clinical Success Bacteriological Success
n/N 1 % n/N 2 %
Penicillin-resistant 21/21 100% 3 21/21 100%
2nd generation cephalosporin-resistant 25/26 96% 25/26 96%
Macrolide-resistant 4 22/23 96% 22/23 96%
Trimethoprim/sulfamethoxazole-resistant 28/30 93% 28/30 93%
Tetracycline-resistant 17/18 94% 17/18 94%

1 n = number of patients successfully treated; N = number of patients with MDRSP (from a total of 37 patients)
2 n = number of patients successfully treated (presumed eradication or eradication); N = number of patients with MDRSP (from a total of 37 patients)
3 One patient had a respiratory isolate that was resistant to penicillin and cefuroxime but a blood isolate that was intermediate to penicillin and cefuroxime. The patient is included in the database based on the respiratory isolate.
4 Azithromycin, clarithromycin, and erythromycin were the macrolide antimicrobials tested.

Not all isolates were resistant to all antimicrobial classes tested. Success and eradication rates are summarized in the table below:

S. pneumoniae with
MDRSP
Clinical Success Bacteriological
Eradication Rate
Resistant to 2 antimicrobials 12/13 (92.3 %) 12/13 (92.3 %)
Resistant to 3 antimicrobials 10/11 (90.9 %) 1 10/11 (90.9 %)
Resistant to 4 antimicrobials 6/6 (100%) 6/6 (100%)
Resistant to 5 antimicrobials 7/7 (100%) 7/7 (100%)
Bacteremia with MDRSP 9/9 (100%) 9/9 (100%)

1 One patient had a respiratory isolate resistant to 5 antimicrobials and a blood isolate resistant to 3 antimicrobials. The patient was included in the category resistant to 5 antimicrobials.

Acute Bacterial Sinusitis

In a large, controlled double-blind study conducted in the US, AVELOX Tablets (400 mg once daily for ten days) were compared with cefuroxime axetil (250 mg twice daily for ten days) for the treatment of acute bacterial sinusitis. The trial included 457 patients valid for the primary efficacy determination. Clinical success (cure plus improvement) at the 7 to 21 day post-therapy test of cure visit was 90% for AVELOX and 89% for cefuroxime.

An additional non-comparative study was conducted to gather bacteriological data and to evaluate microbiological eradication in adult patients treated with AVELOX 400 mg once daily for seven days. All patients (n = 336) underwent antral puncture in this study. Clinical success rates and eradication/ presumed eradication rates at the 21 to 37 day follow-up visit were 97% (29 out of 30) for Streptococcus pneumoniae, 83% (15 out of 18) for Moraxella catarrhalis, and 80% (24 out of 30) for Haemophilus influenzae.

Uncomplicated Skin and Skin Structure Infections

A randomized, double-blind, controlled clinical trial conducted in the US compared the efficacy of AVELOX 400 mg once daily for seven days with cephalexin HCl 500 mg three times daily for seven days. The percentage of patients treated for uncomplicated abscesses was 30%, furuncles 8%, cellulitis 16%, impetigo 20%, and other skin infections 26%. Adjunctive procedures (incision and drainage or debridement) were performed on 17% of the AVELOX treated patients and 14% of the comparator treated patients. Clinical success rates in evaluable patients were 89% (108/122) for AVELOX and 91% (110/121) for cephalexin HCl.

Complicated Skin and Skin Structure Infections

Two randomized, active controlled trials of cSSSI were performed. A double-blind trial was conducted primarily in North America to compare the efficacy of sequential IV/PO AVELOX 400 mg QD for 7-14 days to an IV/PO beta-lactam/beta-lactamase inhibitor control in the treatment of patients with cSSSI. This study enrolled 617 patients, 335 of which were valid for the primary efficacy analysis. A second open-label International study compared AVELOX 400 mg QD for 7-21 days to sequential IV/PO beta-lactam/beta-lactamase inhibitor control in the treatment of patients with cSSSI. This study enrolled 804 patients, 632 of which were valid for the primary efficacy analysis. Surgical incision and drainage or debridement was performed on 55% of the moxifloxacin treated and 53% of the comparator treated patients in these studies and formed an integral part of therapy for this indication. Success rates varied with the type of diagnosis ranging from 61% in patients with infected ulcers to 90% in patients with complicated erysipelas. These rates were similar to those seen with comparator drugs. The overall success rates in the evaluable patients and the clinical success by pathogen are shown below:

Overall Clinical Success Rates in Patients with Complicated Skin and Skin Structure Infections
Study Moxifloxacin
n/ N (%)
Comparator
n/N (%)
95% Confidence
Interval
North America 125/162 (77.2%) 141/173 (81.5%) -14.4%, 2%
International 254/315 (80.6%) 268/317 (84.5%) -9.4%, 2.2%
Clinical Success Rates by Pathogen in Patients with Complicated Skin and Skin Structure Infections
Pathogen Moxifloxacin
n/ N (%)
Comparator
n/N (%)
Staphylococcus aureus
(methicillin-susceptible strains) 1
106/129 (82.2%) 120/137 (87.6%)
Escherichia coli 31/38 (81.6 %) 28/33 (84.8 %)
Klebsiella pneumoniae 11/12 (91.7 %) 7/10 (70%)
Enterobacter cloacae 9/11 (81.8%) 4/7 (57.1%)

1 methicillin susceptibility was only determined in the North American Study

Complicated Intra-Abdominal Infections

Two randomized, active controlled trials of cIAI were performed. A double-blind trial was conducted primarily in North America to compare the efficacy of sequential IV/PO AVELOX 400 mg QD for 5-14 days to IV/ piperacillin/tazobactam followed by PO amoxicillin/clavulanic acid in the treatment of patients with cIAI, including peritonitis, abscesses, appendicitis with perforation, and bowel perforation. This study enrolled 681 patients, 379 of which were considered clinically evaluable. A second open-label international study compared AVELOX 400 mg QD for 5-14 days to IV ceftriaxone plus IV metronidazole followed by PO amoxicillin/clavulanic acid in the treatment of patients with cIAI. This study enrolled 595 patients, 511 of which were considered clinically evaluable. The clinically evaluable population consisted of subjects with a surgically confirmed complicated infection, at least 5 days of treatment and a 25-50 day follow-up assessment for patients at the Test of Cure visit. The overall clinical success rates in the clinically evaluable patients are shown below:

Clinical Success Rates in Patients with Complicated Intra-Abdominal Infections
Study Moxifloxacin
n/ N (%)
Comparator
n/N (%)
95% Confidence
Interval
North America (overall) 146/183 (79.8 %) 153/196 (78.1 %) -7.4%,9.3%
   Abscess 40/57 (70.2 %) 49/63 (77.8 %) 1 NA 2
   Non-abscess 106/126 (84.1 %) 104/133 (78.2 %) NA
International (overall) 199/246 (80.9 %) 218/265 (82.3 %) -8.9 %,4.2%
   Abscess 73/93 (78.5 %) 86/99 (86.9 %) NA
   Non-abscess 126/153 (82.4 %) 132/166 (79.5 %) NA

1 excludes 2 patients who required additional surgery within the first 48 hours.
2 NA - not applicable

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