Cefixime is a third generation oral bactericidal cephalosporin.
The chemical formula is C16H15N5O7S2, 3H2O and MW is 507.50 as the trihydrate. The structure is:
Mechanism of action of cefixime is similar to penicillin. Cefixime acts by inhibiting bacterial cell wall synthesis. Lack of bacterial cell wall results in death due to lysis of bacteria.
Food does not interfere with extent of absorption of cefixime but it delays time required to attain peak plasma concentration. Average peak concentrations produced by oral suspension are approximately 25%-50% higher than the tablets. Tablets should not be replaced for oral suspension in the treatment of otitis media due to lack of bioequivalence.
Cefixime is extremely stable in the presence of β-lactamase enzymes hence many organisms resistant to penicillins and some cephalosporins may be susceptible to cefixime. Cefixime is highly active against gram negative cocci, gram negative bacilli and anaerobes than gram positive cocci and bacilli. It is not active against pseudomonas.
Cefixime is used in treatment of uncomplicated urinary tract infections, otitis media, acute bronchitis, acute exacerbation of chronic bronchitis, uncomplicated gonorrhoea.
|All indications||400 mg daily||8 mg/kg/day|
The recommended formulation in children is suspension. Children weighing more than 50 kg or older than 12 years should be treated with the recommended adult dose of cefixime. In the treatment of infections due to S. pyogenes, the treatment should be for at least 10 days.
Cefixime is contraindicated in patients with known allergy to the cephalosporin group of antibiotics. Cefixime should be used during pregnancy only if clearly needed. Dose reduction needed in patients with renal impairment.
Side effects of cefixime includes diarrhea, loose stools, abdominal pain, dyspepsia, nausea, vomiting, pseudomembranous colitis, hypersensitivity reactions, hepatic toxicity, renal toxicity, headaches, dizziness and seizures.
Cefixime is a third generation oral cephalosporin.
Oral: 200, 400 mg tablets; powder for oral suspension, 100 mg/5 mL
Like other cephalosporins, cefixime possesses a mechanism of action similar to penicillins i.e. inhibition of transpeptidation process resulting in the formation of imperfect cell wall; osmotic drive from the outside isotonic environment of the host cell to the inside of the hypertonic bacterial cytoplasm and finally activation of the autolysin enzyme leading to the lysis of bacteria. Thus cefixime is also a bactericidal drug.
The following organisms are resistant to cefixime:
Resistance to cefixime like other cephalosporins is due to:
This can lead to the binding of the cephalosporin to Beta –lactamases which hydrolyzes the Beta -lactam ring and inactivates the cephalosporin.
Streptococcus pneumoniae become resistant to the cephalosporins of the 3rd generation by alterations in the 2 penicillin binding proteins (1A & 2X).
Destruction by hydrolysis of beta lactam structure is the most predominant way of resistance to cefixime like other cephalosporins. Enormous amounts of Beta-lactamase are released by many gram positive organisms. The gram negative bacteria produce decreased amounts of the beta lactamase enzyme but its periplasmic position makes them more capable of destructing the cephalosporins.
After oral intake cefixime undergoes about 40%-50% absorption. But, when administered with food time to maximal absorption is increased about 0.8 hours. It has a plasma t1/2 of 3–4 hours. Peak serum concentrations reach between 2 and 6 hours after oral administration. Average peak concentrations produced by oral suspension are approximately 25%-50% higher than the tablets. Tablets should not be replaced for oral suspension in the treatment of otitis media due to lack of bioequivalence.
Cefixime is not metabolized significantly. It is both excreted in the urine and eliminated in the bile. About 50% is excreted in urine without any metabolism within one day. The serum protein binding is approximately 65%. Cefixime is not cleared significantly from the blood by haemodialysis or peritoneal dialysis.
Cefixime is indicated for treatment of the following conditions:
|All indications||400 mg daily||8 mg/kg/day|
Short term animal studies and in vitro studies have not shown any carcinogenic or mutagenic activity or impairment of fertility with cefixime.
It is a category B drug and animal studies have not shown any teratogenic effect.
Distribution of cefixime in human milk is not known.
It has not been studied in children < 6 months old.
The dose should be adjusted in accordance with the severity of the renal impairment.
Cefixime is contraindicated in patients with known allergy to the cephalosporin group of antibiotics.
The commonly observed adverse effects are:
CNS: Convulsions, giddiness