What it's for (Indications)
- Cefixime, a third-generation cephalosporin antibiotic, is indicated for the treatment of various infections caused by susceptible strains of microorganisms.
- These include uncomplicated urinary tract infections (e.
- g.
- , cystitis, pyelonephritis), otitis media caused by *Haemophilus influenzae*, *Moraxella catarrhalis*, and *Streptococcus pyogenes*, pharyngitis and tonsillitis caused by *Streptococcus pyogenes*, acute exacerbations of chronic bronchitis due to *Streptococcus pneumoniae* and *Haemophilus influenzae*, and uncomplicated gonorrhea (cervical/urethral) caused by *Neisseria gonorrhoeae*.
- Its broad spectrum of activity against both Gram-positive and Gram-negative bacteria makes it a valuable therapeutic option for these conditions when specific bacterial susceptibility is confirmed or highly suspected.
- Proper diagnosis and susceptibility testing are crucial to guide appropriate antibiotic selection and prevent the development of antibiotic resistance, ensuring optimal patient outcomes.
Dosage Information
| Type | Guideline |
|---|---|
| Standard | The dosage of cefixime varies based on the type and severity of the infection, as well as patient age, weight, and renal function. For adults and adolescents (12 years and older), the usual recommended oral dosage is 400 mg once daily or 200 mg every 12 hours. The duration of therapy typically ranges from 7 to 14 days, depending on the specific infection being treated. For uncomplicated gonorrhea, a single oral dose of 400 mg is usually administered. In pediatric patients (6 months to 12 years), the recommended dosage is 8 mg/kg/day, administered as a single daily dose or in two divided doses (4 mg/kg every 12 hours). For children weighing more than 45 kg or older than 12 years, the adult dosage may be used. Dosage adjustments are necessary for patients with renal impairment (creatinine clearance less than 60 mL/min); for severe renal impairment, a reduction to 200 mg once daily is generally advised. Strict adherence to prescribed dosage and duration is critical to maximize efficacy and minimize the risk of resistance. |
Safety & Warnings
Common Side Effects
- Cefixime, like other antimicrobial agents, can cause a range of side effects, most commonly affecting the gastrointestinal system.
- These frequently reported adverse reactions include diarrhea, loose stools, abdominal pain, nausea, vomiting, and dyspepsia.
- The incidence of diarrhea can be particularly noteworthy with oral cephalosporins.
- Other potential side effects include headache, dizziness, and fatigue.
- Hypersensitivity reactions, ranging from mild skin rashes (e.
- g.
- , maculopapular rash, urticaria) to severe, life-threatening conditions like anaphylaxis, angioedema, and serum sickness-like reactions, can occur and require immediate medical attention.
- Hematologic abnormalities such as eosinophilia, thrombocytopenia, leukopenia, and rarely, aplastic anemia or hemolytic anemia, have been reported.
- Hepatic enzyme elevations (e.
- g.
- , AST, ALT, alkaline phosphatase) and renal function abnormalities have also been observed.
- Prolonged use may lead to superinfection, including candidiasis or, more seriously, *Clostridioides difficile*-associated diarrhea (CDAD), which can range from mild diarrhea to fatal colitis.
- Patients should be advised to report any persistent or severe adverse effects to their healthcare provider promptly.
Serious Warnings
- Black Box Warning: *Cefixime does not carry a formal FDA Black Box Warning.* However, due to the inherent risks associated with broad-spectrum antibiotic use, several **Serious Warnings** are critical for healthcare providers and patients to consider. Severe hypersensitivity reactions, including anaphylaxis, angioedema, and serum sickness-like reactions, can occur with cefixime, necessitating immediate discontinuation and appropriate emergency management. Patients with a history of penicillin allergy should be carefully evaluated due to potential cross-reactivity. Furthermore, *Clostridioides difficile*-associated diarrhea (CDAD) has been reported with nearly all antibacterial agents, including cefixime, and its severity can range from mild diarrhea to fatal colitis. It is imperative to consider CDAD in the differential diagnosis for any patient presenting with diarrhea following antibiotic use. Treatment with antibacterial agents alters the normal flora of the colon, potentially leading to *C. difficile* overgrowth. Additionally, severe cutaneous adverse reactions (SCARs), such as Stevens-Johnson Syndrome (SJS), toxic epidermal necrolysis (TEN), and Drug Reaction with Eosinophilia and Systemic Symptoms (DRESS), have been reported with cephalosporins, and patients should be advised to seek immediate medical attention if skin rashes or blistering occurs.
- Patients should be thoroughly evaluated for a history of hypersensitivity reactions to cefixime, other cephalosporins, penicillins, or other drugs before initiating therapy.
- There is a risk of cross-hypersensitivity between penicillin and cephalosporin antibiotics, ranging from 5-10%.
- Severe hypersensitivity reactions, including anaphylaxis, can occur and necessitate immediate discontinuation and appropriate emergency treatment.
- *Clostridioides difficile*-associated diarrhea (CDAD) has been reported with nearly all antibacterial agents, including cefixime, and can range in severity from mild diarrhea to fatal colitis.
- It is crucial to consider CDAD in patients who present with diarrhea following antibiotic administration.
- Treatment with antibacterial agents alters the normal flora of the colon, leading to overgrowth of *C.
- difficile*.
- Careful monitoring for signs of renal impairment is essential, and dosage adjustments are required for patients with significant renal dysfunction.
- Prolonged use of cefixime may result in the overgrowth of non-susceptible organisms, necessitating careful observation for superinfection.
- Hemolytic anemia, including fatalities, has been reported with cephalosporin-class antibiotics, though rare.
- Convulsions have also been reported with some cephalosporins, especially in patients with renal impairment where dosage was not reduced.
How it Works (Mechanism of Action)
Cefixime exerts its bactericidal effect by inhibiting bacterial cell wall synthesis. As a beta-lactam antibiotic, it achieves this by binding to specific penicillin-binding proteins (PBPs) located inside the bacterial cell wall. PBPs are enzymes (transpeptidases and carboxypeptidases) that are crucial for the synthesis of peptidoglycan, a vital component of the bacterial cell wall that provides structural integrity. By interfering with the transpeptidation step of peptidoglycan synthesis, cefixime prevents the cross-linking of peptidoglycan strands, leading to a defective and unstable cell wall. This compromised cell wall integrity ultimately results in osmotic lysis and death of the bacterial cell. Cefixime demonstrates good stability in the presence of various bacterial beta-lactamases, including those produced by *Haemophilus influenzae* and *Neisseria gonorrhoeae*, which contributes to its effectiveness against certain resistant strains. Its affinity for PBPs and resistance to beta-lactamase degradation are key factors in its mechanism of action.