Cefixime trihydrate is a broad-spectrum, third-generation cephalosporin antibiotic with significant clinical importance in treating various bacterial infections. As an orally active semisynthetic cephalosporin, it has demonstrated efficacy against numerous gram-positive and gram-negative bacterial pathogens.
This comprehensive review examines the pharmaceutical properties, clinical applications, and safety profile of cefixime trihydrate, providing healthcare professionals with essential information for appropriate therapeutic decision-making.
Introduction
Cefixime is a broad-spectrum antibiotic belonging to the third-generation cephalosporin class. The trihydrate form represents the crystalline structure containing three water molecules per cefixime molecule, which contributes to its stability and bioavailability. First approved in the United States in 1986, cefixime has become an important antimicrobial agent in the treatment of various bacterial infections.
As a beta-lactam antibiotic, cefixime works through inhibition of bacterial cell wall synthesis, a mechanism that has proven effective against many clinically significant pathogens. Compared to earlier generations of cephalosporins, third-generation agents like cefixime demonstrate enhanced activity against gram-negative organisms while maintaining efficacy against many gram-positive bacteria.
Chemical Structure
Cefixime trihydrate has the molecular formula C₁₆H₁₅N₅O₇S₂·3H₂O and a molecular weight of 507.50 g/mol. The IUPAC name for this compound is (6R,7R)-7-[(2Z)-2-(2-amino-1,3-thiazol-4-yl)-2-[(carboxymethoxy)imino]acetamido]-3-ethenyl-8-oxo-5-thia-1-azabicyclo[4.2.0]oct-2-ene-2-carboxylic acid trihydrate.
The compound consists of a beta-lactam ring fused with a dihydrothiazine ring, forming the characteristic cephalosporin nucleus. The trihydrate structure indicates that three water molecules are incorporated into the crystalline structure of the drug. This chemical conformation contributes to its solubility profile and pharmaceutical stability.
The CAS registry number assigned to cefixime trihydrate is 125110-14-7, which uniquely identifies this specific salt form of the drug in chemical databases and regulatory documentation.
Cefixime-Based Medicines List
Cefixime trihydrate is marketed under various brand names globally. Here are eight prominent commercial formulations:
- Suprax – The original brand name in the United States, available as capsules, tablets, chewable tablets, and oral suspension
- 3-C – Manufactured by Edruc Limited, available as capsules (200 mg, 400 mg) and powder for suspension (100 mg/5 ml)
- Afix – Produced by Aristopharma Ltd., offered as capsules, tablets, and powder for suspension in various strengths
- Afixime – Marketed by Asiatic Laboratories Ltd., available in multiple formulations
- Caricef – Manufactured by SAMI Pharmaceuticals, widely used in Pakistan and South Asia
- Cebosh – Produced by Bosch Pharmaceuticals, another regional formulation
- Cefiget – Marketed by Getz Pharma Pakistan, available in various dosage forms
- 3RD Cef – Produced by Medimet Pharmaceuticals Ltd., available as tablets and powder for suspension
Mechanism of Action
Cefixime trihydrate exerts its antibacterial effects through interference with bacterial cell wall synthesis. Bacteria possess a cell wall comprising a glycopeptide polymer known as peptidoglycan, which provides structural integrity and protection against osmotic lysis. This cell wall is synthesized and remodeled through the action of enzymes called penicillin-binding proteins (PBPs).
Cefixime, like other beta-lactam antibiotics, binds to these PBPs, particularly those responsible for the final cross-linking steps in peptidoglycan synthesis. This binding inhibits the transpeptidation process essential for forming the three-dimensional structure of the bacterial cell wall.
The inhibition of PBPs leads to impaired cell wall homeostasis, compromised cellular integrity, and ultimately bacterial cell death. Specifically, cefixime disrupts the enzymes responsible for creating peptidoglycan cross-linkages, weakening the structural framework of the bacterial cell wall.
An important characteristic of third-generation cephalosporins, including cefixime trihydrate, is their enhanced stability in the presence of beta-lactamase enzymes compared to first and second-generation cephalosporins. This stability extends their spectrum of activity to include many beta-lactamase-producing organisms that would otherwise destroy earlier generation cephalosporins.
Pharmacokinetics
The pharmacokinetic profile of cefixime trihydrate explains its clinical efficacy and dosing recommendations. After oral administration, peak serum concentrations vary depending on the dosing regimen. In a study of healthy volunteers receiving multiple doses, the 200 mg twice-daily regimen produced mean peak serum concentrations (Cmax) of 1.67, 1.75, and 1.87 μg/mL on days 1, 8, and 15, respectively. The 400 mg once-daily regimen resulted in higher concentrations of 2.76, 3.04, and 2.67 μg/mL on the same days.
Urinary excretion accounts for approximately 11.9-14.5% of the dose in the 200 mg twice-daily regimen and 9.9-12.4% in the 400 mg once-daily regimen. Importantly, no significant accumulation of cefixime was observed in serum or urine over the 15-day dosing period, indicating that steady-state concentrations are maintained without drug buildup. The pharmacokinetic parameters showed no clinically significant changes over the treatment course, supporting the reliability of both once-daily and twice-daily dosing regimens.
In patients with renal impairment, dose adjustments are necessary. For those with creatinine clearance (CrCl) between 21-60 mL/min, the recommended dose is 260 mg/day, while patients with CrCl ≤20 mL/min or on continuous peritoneal dialysis should receive 200 mg/day.
Therapeutic Uses
Cefixime trihydrate has been approved for the treatment of various bacterial infections, demonstrating efficacy against numerous pathogens.
| Infection Type | Target Pathogens | Recommended Dosage | Duration |
|---|---|---|---|
| Urinary Tract Infections | Escherichia coli, Proteus mirabilis | 400 mg/day PO in single dose or divided q12hr | 7-10 days |
| Otitis Media | Haemophilus influenzae, Moraxella catarrhalis, Streptococcus pyogenes | 400 mg/day PO in single dose or divided q12hr | 10 days |
| Pharyngitis/Tonsillitis | Streptococcus pyogenes | 400 mg/day PO in single dose or divided q12hr | 10 days |
| Acute Exacerbations of Chronic Bronchitis | Streptococcus pneumoniae, Haemophilus influenzae | 400 mg/day PO in single dose or divided q12hr | 7-10 days |
| Uncomplicated Gonorrhea | Neisseria gonorrhoeae | 400 mg PO once (plus azithromycin 1g PO once) | Single dose |
| Typhoid Fever (off-label) | Salmonella typhi | 15-20 mg/kg/day; not to exceed 100-200 mg BID | 7-14 days |
It’s important to note that while cefixime was previously used as a first-line treatment for gonorrhea, current CDC guidelines no longer recommend it as primary therapy due to emerging resistance patterns.
Side Effects
Cefixime trihydrate, like other antibiotics, can cause various adverse effects ranging from mild to severe. Common side effects include gastrointestinal disturbances such as stomach upset or pain, diarrhea, nausea, constipation, loss of appetite, and gas. Other frequently reported effects include headache, dizziness, anxiety, drowsiness, increased night-time urination, runny nose, sore throat, cough, and vaginal itching or discharge.
More serious but less common side effects require immediate medical attention. These include severe allergic reactions (manifesting as hives, difficult breathing, swelling of the face, lips, tongue, or throat), severe stomach pain, watery or bloody diarrhea, jaundice (yellowing of the skin or eyes), confusion, weakness, seizures, unusual bleeding or bruising, and skin reactions with blistering and peeling. Patients should be monitored for signs of Clostridioides difficile-associated diarrhea, which can occur during or after treatment.
The allergic potential of cefixime is an important consideration, especially for patients with known hypersensitivity to cephalosporins or penicillins. Cross-reactivity between these beta-lactam antibiotics may occur in sensitive individuals, necessitating careful patient history evaluation before prescribing.
Drug Interactions
Cefixime trihydrate has been documented to interact with numerous medications. According to available data, there are 63 drugs known to interact with cefixime, of which 6 interactions are classified as major, 55 as moderate, and 2 as minor. Additionally, 5 disease interactions have been identified that may affect the safe use of cefixime.
The drug’s absorption may be influenced by certain foods and other medications. Research has shown that flavonoids from plants can alter the transport of cefixime via PEPT1 in intestinal cells. Specific flavonoids such as quercetin, genistein, naringin, diosmin, acacetin, and chrysin were found to increase cefixime uptake by up to 60% by activating apical Na+/H+ exchange.
When prescribing cefixime, healthcare providers should carefully review the patient’s complete medication list to avoid potential drug interactions. Special attention should be paid to anticoagulants, probenecid, and nephrotoxic drugs which may have clinically significant interactions with cefixime.
Safety Considerations
Cefixime trihydrate carries a pregnancy category B rating, indicating no proven risk in humans has been established. Animal studies have failed to reveal evidence of fetal harm or impaired fertility at doses up to 400 times the recommended human dose, though increased incidence of abortion was noted at levels reaching maternal toxicity.
Regarding lactation, cefixime is known to be excreted into human milk, and its use is generally not recommended during breastfeeding. A decision should be made to discontinue breastfeeding or discontinue the drug, taking into account the importance of the medication to the mother. The American Academy of Pediatrics considers other cephalosporins (such as cefadroxil and cefazolin) as compatible with breastfeeding, though maternal doses of cephalosporins have been associated with reports of neonatal diarrhea and thrush.
Patients with known allergies to cephalosporins should not take cefixime. Those with allergies to penicillins should use cefixime with caution due to the potential for cross-reactivity. The chewable tablet form may contain phenylalanine, warranting caution in patients with phenylketonuria (PKU). Additionally, the suspension form contains sucrose, which is a consideration for patients with diabetes.
Regulatory Status
Cefixime trihydrate received FDA approval in the United States, with the original approval dating back to 1986. The drug is available by prescription only and is marketed under various brand and generic names. The FDA has approved multiple formulations, including capsules (400 mg), tablets (400 mg), chewable tablets (100 mg, 150 mg, 200 mg), and oral suspensions (100 mg/5 mL, 200 mg/5 mL, 500 mg/5 mL).
Generic formulations of cefixime have also received regulatory approval. For example, in 2015, the FDA approved Aurobindo Pharma’s Abbreviated New Drug Application (ANDA) for Cefixime for Oral Suspension USP, 100 mg/5 mL and 200 mg/5 mL. The drug is commercially available globally, with numerous pharmaceutical companies producing generic versions under various brand names across different countries, particularly in South Asia where it is extensively used for bacterial infections.
Conclusion
Cefixime trihydrate remains an important broad-spectrum antibiotic in the healthcare arsenal, particularly useful for treating respiratory, urinary, and certain sexually transmitted infections. Its oral bioavailability, once-daily dosing option, and efficacy against many common pathogens make it a valuable therapeutic agent. However, emerging antibiotic resistance patterns, potential for adverse effects, and specific contraindications necessitate judicious use of this antimicrobial agent.
Healthcare providers should consider local resistance patterns, individual patient factors, and current treatment guidelines when prescribing cefixime trihydrate to ensure optimal therapeutic outcomes while minimizing risks associated with antibiotic use.
