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Medzyme: Pharmacological Classification: Antibacterial.
Pharmacology: Cefuroxime is a second-generation cephalosporin antibiotic with similar or less activity than first-generation cephalosporins against gram-positive cocci, but relatively resistant to beta-lactamases produced by Gram-negative bacteria.
Pharmacokinetics: After oral administration, cefuroxime axetil is absorbed from the gastrointestinal tract and rapidly hydrolyzed in the intestinal mucosa and blood to release cefuroxime into the circulation.
Following administration of cefuroxime axetil tablets, peak serum levels (2.9 mg/mL for a 125 mg dose, 4.4 mg/mL for a 250 mg dose, 7.7 mg/mL for a 500 mg dose and 13.6 mg/mL for a 1 g dose) occur approximately 2.4 hours after dosing when taken with food.
Absorption of cefuroxime axetil suspension is enhanced in the presence of food. The rate of absorption of cefuroxime from the suspension compared with the tablets is reduced, leading to later, lower peak serum levels and slightly reduced systemic bioavailability (4-17% or less). The serum half-life is between 1 and 1.5 hours.
Protein binding has been variously stated as 33-50% depending on the methodology used. Cefuroxime is not metabolized and is excreted by glomerular filtration and tubular secretion.
Concurrent administration of probenecid increases the area under the mean serum concentration time curve by 50%. Serum levels of cefuroxime are reduced by dialysis. Cefuroxime passes the blood-brain barrier when the meninges are inflamed.
Medzyme Vial: Pharmacology: The bactericidal action of cefuroxime results from inhibition of bacterial cell-wall synthesis by binding to bacterial essential target proteins, penicillin-binding proteins.
Cefuroxime has a well-characterized and effective antibacterial activity against a wide range of common pathogens including beta-lactamase-producing strains of both Gram-positive and Gram-negative bacteria. Cefuroxime has good stability against many beta-lactamase produced by bacteria, especially enterobacteria.
Antibacterial spectrum: Cefuroxime is active against aerobic and anaerobic Gram-negative and Gram-positive cocci including penicillinase producing Staphylococci and active against Gram-negative intestinal bacteria. Cefuroxime has high potency and thus low MIC-values for Streptococci (group A, B, C and G), Gonococci and Meningococci.
The drug was originally presented to have low MIC-values for beta-lactamase producing Gonococci, Moraxella catarrhalis, Haemophilus influenzae and Klebsiella spp. In Vietnam, this has now changed and many bacteria are resistant. Strains of Enterobacter, Bacteroides fragilis and indole-positive Proteus have decreased sensitivity.
Clostridium difficile, Pseudomonas spp., Campylobacter spp., Acinetobacter calcoaceticus, Legionella spp. are not susceptible to Cefuroxime.
Methicillin-resistant strains of Staphylococcus aureus, Staphylococcus epidermidis are also resistant against cefuroxime. Listeria monocytogenes and most strains of Enterococci are resistant to cefuroxime.
The data from 1997 and 1999 ASTS reports have shown that cefuroxime still has useful activity against Salmonella with susceptibility of 100% of the testes isolates in Hue central hospital in 1996.
The current pathogenic bacterial resistance against cefuroxime has been reported to increase as follows: Shigella flexneri has been reported to be resistant in 11% of the isolates studied in 1998; Proteus mirabilis, 28.6% in 1997; Citrobacter 46.7% in 1997; E.coli, 33.5% in 1998; Klebsiella spp., 57% in 1997; Enterobacter, 59% in 1998; Streptococcus viridans, 31% in 1996; S. aureus, 33% in 1998.
Recent studies in Vietnamese healthy children, colonised with Haemophilus influenzae, also indicated a surprisingly high rate of cefuroxime resistance. Haemophilus influenzae was totally resistant against cefuroxime in 27% of the studied isolates (ASTS Information No. 4/1999 on pathogenic bacterial resistance against antibiotics). This is a serious situation, showing that broad-spectrum antibiotics must be restricted only for use in patients with severe infections.
Pharmacokinetics: Peak plasma concentrations about 27 μg/ml occurred at 45 minutes after an I.M. dose of 750 mg, and peak plasma concentrations about 50 μg/ml at 15 minutes after an I.V. dose of 750 mg. Therapeutic serum concentrations with measurable amounts are present 8 hours after a dose. 50% cefuroxime in the circulation is bound to plasma proteins. The plasma half-life is about 70 minutes and is prolonged with renal impairment and in neonates.
Cefuroxime is widely distributed in the body including pleural fluid, sputum, bone, synovial fluid and aqueous humor. The blood-brain barrier can be passed by cefuroxime when the meninges are inflamed. It crosses the placenta and has been detected in breast milk. Cefuroxime is not metabolized and is excreted unchanged to approximately 50% by glomerular filtration and 50% through the renal tubular secretion. High concentrations are achieved in the urine. Only very small amounts of cefuroxime are excreted in bile.
