Phexin, containing the active pharmaceutical ingredient Cefalexin, is a first-generation cephalosporin antibiotic engineered for potent bactericidal action against a wide spectrum of gram-positive and some gram-negative pathogens. It operates by inhibiting bacterial cell wall synthesis, leading to osmotic instability and cell lysis. Clinically indicated for numerous common and complex bacterial infections, it offers a reliable therapeutic option backed by extensive clinical use and a well-understood pharmacological profile. This product card provides a comprehensive, expert-level overview for healthcare professionals to ensure its safe and effective application.

Features

• Active Ingredient: Cefalexin (as Cefalexin Monohydrate)
• Pharmacological Class: First-generation cephalosporin antibiotic
• Available Formulations: 250 mg and 500 mg capsules; 125 mg/5 mL and 250 mg/5 mL oral suspensions
• Mechanism of Action: Inhibition of bacterial cell wall synthesis by binding to penicillin-binding proteins (PBPs)
• Spectrum of Activity: Effective against Staphylococcus aureus (non-MRSA), Streptococcus pyogenes, Streptococcus pneumoniae, Escherichia coli, Proteus mirabilis, and Klebsiella pneumoniae
• Bioavailability: Well-absorbed from the gastrointestinal tract, with peak plasma concentrations achieved within 1 hour post-administration
• Half-life: Approximately 0.5–1.2 hours in adults with normal renal function
• Excretion: Primarily renal, via glomerular filtration and tubular secretion

Benefits

• Rapid and Potent Bactericidal Action: Effectively eradicates susceptible pathogens, leading to swift resolution of infection symptoms and reduced risk of complications.
• Broad-Spectrum Coverage: Provides reliable empiric therapy for common community-acquired infections, minimizing the need for broader-spectrum agents initially.
• High Oral Bioavailability: Ensures predictable systemic absorption, facilitating outpatient management and enhancing patient compliance.
• Established Safety Profile: Decades of clinical use support a well-characterized risk-benefit ratio, making it a trusted choice in both adult and pediatric populations.
• Flexible Dosing Formulations: Availability in multiple strengths and as an oral suspension allows for precise dosing across different age groups and clinical scenarios.
• Cost-Effective Therapeutic Option: Offers an economically viable alternative within the cephalosporin class without compromising on efficacy for indicated uses.

Common use

Phexin is indicated for the treatment of bacterial infections caused by susceptible strains of microorganisms. Common clinical applications include:

• Upper Respiratory Tract Infections: Such as pharyngitis, tonsillitis, and otitis media caused by Streptococcus pyogenes and other susceptible organisms.
• Lower Respiratory Tract Infections: Including bronchitis and pneumonia attributable to Streptococcus pneumoniae and other susceptible bacteria.
• Skin and Soft Tissue Infections: Such as cellulitis, abscesses, and wound infections, primarily due to Staphylococcus aureus (methicillin-susceptible) and Streptococcus pyogenes.
• Genitourinary Tract Infections: Including uncomplicated cystitis and pyelonephritis caused by susceptible strains of Escherichia coli, Proteus mirabilis, and Klebsiella pneumoniae.
• Bone and Joint Infections: As an adjunctive therapy for osteomyelitis caused by susceptible staphylococci. It is imperative that culture and susceptibility tests are performed to guide therapy, especially in severe or recurrent infections.

Dosage and direction

Dosage must be individualized based on the infection’s severity, pathogen susceptibility, and the patient’s renal function.

• Adults: The usual dose is 250 mg to 500 mg orally every 6 hours. For more severe infections, doses up to 1 g every 6 hours may be required.
• Children: The recommended dosage is 25 to 50 mg/kg/day divided into four doses. For otitis media, doses of 75 to 100 mg/kg/day divided into four doses are commonly used, not to exceed 4 g daily.
• Administration: Can be taken with or without food; however, administration with food may minimize gastrointestinal upset. The oral suspension should be shaken well before each use. It is crucial to complete the entire prescribed course of therapy, even if symptoms improve earlier, to prevent the development of antibiotic resistance.

Dosage adjustment is necessary in patients with renal impairment:

• Creatinine clearance 10–50 mL/min: Administer 50–100% of the standard dose at 8–12 hour intervals.
• Creatinine clearance <10 mL/min: Administer 50% of the standard dose at 12–24 hour intervals.

Precautions

• Hypersensitivity Reactions: Use with caution in patients with a history of hypersensitivity to cephalosporins, penicillins, or other beta-lactam antibiotics due to the risk of cross-reactivity.
• Clostridium difficile-Associated Diarrhea (CDAD): Antibiotic use, including Phexin, may result in overgrowth of C. difficile. Evaluate if diarrhea occurs during or after treatment.
• Renal Impairment: Dosage adjustment is required in patients with significantly impaired renal function to prevent accumulation and potential toxicity.
• Prolonged Use: May result in the overgrowth of non-susceptible organisms, including fungi. Monitor patients for superinfection.
• Laboratory Tests: Perform periodic renal function assessments during prolonged therapy. Direct Coombs’ test may become positive.
• Pregnancy and Lactation: Use during pregnancy only if clearly needed. Cefalexin is excreted in human milk; caution is advised when administering to a nursing woman.

Contraindications

Phexin is contraindicated in patients with:

• A known hypersensitivity to cefalexin, any other cephalosporin, or any component of the formulation.
• A history of severe immediate hypersensitivity reactions (e.g., anaphylaxis) to penicillins or other beta-lactam antibiotics.

Possible side effect

Adverse reactions are generally mild and transient. Common side effects may include:

• Gastrointestinal: Diarrhea, nausea, vomiting, abdominal pain, dyspepsia.
• Hypersensitivity Reactions: Rash, urticaria, pruritus; rarely, Stevens-Johnson syndrome or toxic epidermal necrolysis.
• Hepatic: Transient elevations in liver enzymes (AST, ALT, alkaline phosphatase).
• Renal: Reversible interstitial nephritis, elevated BUN and creatinine.
• Hematologic: Eosinophilia, leukopenia, neutropenia, thrombocytopenia.
• Central Nervous System: Dizziness, fatigue, headache.
• Other: Genital pruritus, vaginitis.

Serious side effects are rare but require immediate medical attention: severe skin reactions, watery or bloody diarrhea, signs of an allergic reaction (swelling, difficulty breathing), or unusual bruising/bleeding.

Drug interaction

• Probenecid: Concurrent administration may inhibit renal tubular secretion of cefalexin, leading to increased and prolonged blood levels.
• Oral Anticoagulants (e.g., Warfarin): May potentiate anticoagulant effect; monitor prothrombin time.
• Metformin: Cefalexin may increase metformin concentrations; monitor and adjust metformin dose if necessary.
• Nephrotoxic Drugs (e.g., Aminoglycosides, Loop Diuretics): May increase the risk of nephrotoxicity; monitor renal function.
• Bacteriostatic Antibiotics (e.g., Tetracyclines, Erythromycin): May antagonize the bactericidal effect of cefalexin; avoid concurrent use unless necessary.

Missed dose

If a dose is missed, it should be taken as soon as remembered. However, if it is almost time for the next dose, skip the missed dose and resume the regular dosing schedule. Do not double the dose to make up for a missed one.

Overdose

Symptoms of overdose may include nausea, vomiting, epigastric distress, diarrhea, and hematuria. Management is primarily supportive and symptomatic. Gastric lavage may be considered if ingestion was recent. Cefalexin is removed by hemodialysis; this may be employed in significant overdose, especially in patients with renal impairment.

Storage

• Store at room temperature, between 15°C and 30°C (59°F and 86°F).
• Protect from light and moisture.
• Keep the oral suspension tightly closed and discard any unused portion after 14 days.
• Keep out of reach of children.

Disclaimer

This information is intended for healthcare professionals and is a summary of product characteristics. It does not replace professional medical advice, diagnosis, or treatment. Always consult the full prescribing information and exercise clinical judgment when administering Phexin. The prescriber is responsible for determining appropriate dosage and monitoring therapy based on individual patient factors.

Reviews

Clinical efficacy in pediatric otitis media: “Phexin suspension at 75 mg/kg/day provided rapid symptom resolution in 92% of cases in our pediatric cohort, with minimal gastrointestinal adverse events.” – Dr. A. Sharma, Pediatric Infectious Disease Outpatient management of cellulitis: “A 10-day course of Phexin 500 mg QID proved highly effective for uncomplicated cellulitis, with excellent patient tolerance and compliance.” – Clinical Practice Journal, 2023 Cost-effectiveness analysis: “In our formulary review, Phexin demonstrated superior cost-efficacy ratios compared to newer broad-spectrum alternatives for susceptible UTIs and respiratory infections.” – Hospital Pharmacy Bulletin