Cefuroxime Axetil For Oral Suspension

CEFUROXIME AXETIL FOR ORAL SUSPENSION- cefuroxime axetil suspension
Ranbaxy Pharmaceuticals Inc

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

DESCRIPTION

Cefuroxime axetil for oral suspension, USP contains cefuroxime as cefuroxime axetil. Cefuroxime axetil USP is a semisynthetic, broad-spectrum cephalosporin antibiotic for oral administration.

Chemically, cefuroxime axetil, the 1-(acetyloxy) ethyl ester of cefuroxime, is (RS)-1- hydroxyethyl (6R ,7R)-7-[2-(2-furyl)glyoxylamido]-3-(hydroxymethyl)-8-oxo-5-thia-1- azabicyclo[4.2.0]oct-2-ene-2-carboxylate, 7² -(Z)-(O -methyl-oxime), 1-acetate 3-carbamate. Its molecular formula is C₂₀ H₂₂ N₄ O₁₀ S, and it has a molecular weight of 510.48.

Cefuroxime axetil is in the crystalline form and has the following structural formula:

Cefuroxime axetil for oral suspension USP, when reconstituted with water, provides the equivalent of 125 mg or 250 mg of cefuroxime (as cefuroxime axetil) per 5 mL of suspension. Cefuroxime axetil USP for oral suspension contains the following inactive ingredients: aspartame, hypromellose phthalate, mannitol, methacrylic acid copolymer, monosodium citrate, peppermint flavor, silicon dioxide, sodium benzoate, sodium chloride, sucrose, tutti frutti flavor, xanthan gum.

CLINICAL PHARMACOLOGY

Absorption and Metabolism: After oral administration, cefuroxime axetil is absorbed from the gastrointestinal tract and rapidly hydrolyzed by nonspecific esterases in the intestinal mucosa and blood to cefuroxime. Cefuroxime is subsequently distributed throughout the extracellular fluids. The axetil moiety is metabolized to acetaldehyde and acetic acid.

Pharmacokinetics: Approximately 50% of serum cefuroxime is bound to protein. Serum pharmacokinetic parameters for cefuroxime axetil for oral suspension are shown in Table 1.

Table 1. Postprandial Pharmacokinetics of Cefuroxime Administered as Cefuroxime Axetil for Oral Suspension to Pediatric Patients*

Dose† (Cefuroxime Equivalent)	n	Peak Plasma Concentration (mcg/mL)	Time of Peak Plasma Concentration (hr)	Mean Elimination Half-Life (hr)	AUC (mcg-hr mL)
10 mg/kg	8	3.3	3.6	1.4	12.4
15 mg/kg	12	5.1	2.7	1.9	22.5
20 mg/kg	8	7	3.1	1.9	32.8

^* Mean age = 23 months.

^† Drug administered with milk or milk products

Comparative Pharmacokinetic Properties: A 250 mg/5 mL dose of cefuroxime axetil for oral suspension is bioequivalent to 2 times 125 mg/5 mL dose of cefuroxime axetil for oral suspension when administered with food (see Table 2). Cefuroxime axetil for oral suspension was not bioequivalent to cefuroxime axetil tablets when tested in healthy adults. The tablet and powder for oral suspension formulations are NOT substitutable on a milligram-per-milligram basis. The area under the curve for the suspension averaged 91% of that for the tablet, and the peak plasma concentration for the suspension averaged 71% of the peak plasma concentration of the tablets. Therefore, the safety and effectiveness of both the tablet and oral suspension formulations had to be established in separate clinical trials.

Table 2: Pharmacokinetics of Cefuroxime Administered as 250 mg/5 mL or 2 x 125 mg/5 mL Cefuroxime Axetil for Oral Suspension to Adults* With Food

Dose (Cefuroxime Equivalent)	Peak Plasma Concentration (mcg/mL)	Time of Peak Plasma Concentration (hr)	Mean Elimination Half-Life (hr)	AUC (mcg-hr mL)
250 mg/5 mL	2.23	3	1.40	8.92
2 x 125 mg/5 mL	2.37	3	1.44	9.75

^* Mean values of 18 healthy adult volunteers

Food Effect on Pharmacokinetics: All pharmacokinetic and clinical effectiveness and safety studies in pediatric patients using the suspension formulation were conducted in the fed state. No data are available on the absorption kinetics of the suspension formulation when administered to fasted pediatric patients.

Renal Excretion: Cefuroxime is excreted unchanged in the urine; in adults, approximately 50% of the administered dose is recovered in the urine within 12 hours. The pharmacokinetics of cefuroxime in the urine of pediatric patients have not been studied at this time. Until further data are available, the renal pharmacokinetic properties of cefuroxime axetil established in adults should not be extrapolated to pediatric patients.

Because cefuroxime is renally excreted, the serum half-life is prolonged in patients with reduced renal function. In a study of 20 elderly patients (mean age = 83.9 years) having a mean creatinine clearance of 34.9 mL/min, the mean serum elimination half-life was 3.5 hours. Despite the lower elimination of cefuroxime in geriatric patients, dosage adjustment based on age is not necessary (see PRECAUTIONS: Geriatric Use).

Microbiology: The in vivo bactericidal activity of cefuroxime axetil is due to cefuroxime’s binding to essential target proteins and the resultant inhibition of cell-wall synthesis.

Cefuroxime has bactericidal activity against a wide range of common pathogens, including many beta-lactamase-producing strains. Cefuroxime is stable to many bacterial beta-lactamases, especially plasmid-mediated enzymes that are commonly found in enterobacteriaceae.

Cefuroxime has been demonstrated 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 (see INDICATIONS AND USAGE section).

Aerobic Gram-Positive Microorganisms:

Staphylococcus aureus (including beta-lactamase-producing strains)

Streptococcus pneumoniae

Streptococcus pyogenes

Aerobic Gram-Negative Microorganisms:

Escherichia coli

Haemophilus influenzae (including beta-lactamase-producing strains)

Haemophilus parainfluenzae

Klebsiella pneumoniae

Moraxella catarrhalis (including beta-lactamase-producing strains)

Neisseria gonorrhoeae (including beta-lactamase-producing strains)

Spirochetes:

Borrelia burgdorferi

Cefuroxime has been shown to be active in vitro against most strains of the following microorganisms; however, the clinical significance of these findings is unknown.

Cefuroxime exhibits in vitro minimum inhibitory concentrations (MICs) of 4 mcg/mL or less (systemic susceptible breakpoint) against most (> 90%) strains of the following microorganisms; however, the safety and effectiveness of cefuroxime in treating clinical infections due to these microorganisms have not been established in adequate and well-controlled trials.

Aerobic Gram-Positive Microorganisms:

Staphylococcus epidermidis

Staphylococcus saprophyticus

Streptococcus agalactiae

NOTE: Listeria monocytogenes and certain strains of enterococci, e.g., Enterococcus faecalis (formerly Streptococcus faecalis), are resistant to cefuroxime. Methicillin-resistant staphylococci are resistant to cefuroxime.

Aerobic Gram-Negative Microorganisms:

Morganella morganii

Proteus inconstans

Proteus mirabilis

Providencia rettgeri

NOTE: Pseudomonas spp., Campylobacter spp., Acinetobacter calcoaceticus , Legionella spp., and most strains of Serratia spp. and Proteus vulgaris are resistant to most first- and second-generation cephalosporins. Some strains of Morganella morganii , Enterobacter cloacae , and Citrobacter spp. have been shown by in vitro tests to be resistant to cefuroxime and other cephalosporins.

Anaerobic Microorganisms:

Peptococcus niger

NOTE: Most strains of Clostridium difficile and Bacteroides fragilis are resistant to cefuroxime.

Susceptibility Tests: Dilution Techniques: Quantitative methods that are used to determine MICs provide reproducible estimates of the susceptibility of bacteria to antimicrobial compounds. One such standardized procedure uses a standardized dilution method¹ (broth, agar, or microdilution) or equivalent with cefuroxime powder. The MIC values obtained should be interpreted according to the following criteria:

MIC (mcg/mL)	Interpretation
≤ 4	(S) Susceptible
8 to16	(I) Intermediate
≥ 32	(R) Resistant

A report of “Susceptible” indicates that the pathogen, if in the blood, is likely to be inhibited by usually achievable concentrations of the antimicrobial compound in blood. A report of “Intermediate” indicates that inhibitory concentrations of the antibiotic may be achieved if high dosage is used or if the infection is confined to tissues or fluids in which high antibiotic concentrations are attained. This category also provides a buffer zone that prevents small, uncontrolled technical factors from causing major discrepancies in interpretation. A report of “Resistant” indicates that usually achievable concentrations of the antimicrobial compound in the blood are unlikely to be inhibitory and that other therapy should be selected.

Standardized susceptibility test procedures require the use of laboratory control microorganisms. Standard cefuroxime powder should give the following MIC values:

Microorganism	MIC (mcg/mL)
Escherichia coli ATCC 25922	2 to 8
Staphylococcus aureus ATCC 29213	0.5 to 2

Diffusion Techniques: Quantitative methods that require measurement of zone diameters provide estimates of the susceptibility of bacteria to antimicrobial compounds. One such standardized procedure² that has been recommended (for use with disks) to test the susceptibility of microorganisms to cefuroxime uses the 30 mcg cefuroxime disk. Interpretation involves correlation of the diameter obtained in the disk test with the MIC for cefuroxime.

Reports from the laboratory providing results of the standard single-disk susceptibility test with a 30 mcg cefuroxime disk should be interpreted according to the following criteria:

Zone Diameter (mm)	Interpretation
≥ 23	(S) Susceptible
15 to 22	(I) Intermediate
≤ 14	(R) Resistant

Interpretation should be as stated above for results using dilution techniques.

As with standard dilution techniques, diffusion methods require the use of laboratory control microorganisms. The 30 mcg cefuroxime disk provides the following zone diameters in these laboratory test quality control strains:

Microorganism	Zone Diameter (mm)
Escherichia coli ATCC 25922	20 to 26
Staphylococcus aureus ATCC 25923	27 to 35