Cephalexin capsules, USP is a semisynthetic cephalosporin antibacterial drug intended for oral administration. It is 7-(D-α-Amino-α-phenylacetamido)-3-methyl-3-cephem-4-carboxylic acid monohydrate. Cephalexin has the molecular formula C 16 H 17 N 3 O 4 S•H 2 O and the molecular weight is 365.41. Cephalexin has the following structural formula: Each capsule contains cephalexin monohydrate equivalent to 250 mg or 500 mg of cephalexin. The capsules also contain the following inactive ingredients: microcrystalline cellulose, croscarmellose sodium, D&C Yellow No. 10, FD&C Blue No. 1, FD&C Yellow No. 6, gelatin, magnesium stearate, titanium dioxide, and sodium lauryl sulfate. FDA approved dissolution test specifications differs from the USP. structure

Cephalexin capsules are a cephalosporin antibacterial drug indicated for the treatment of the following infections caused by susceptible isolates of designated bacteria: Respiratory tract infection Otitis media Skin and skin structure infections Bone infections Genitourinary tract infections To reduce the development of drug-resistant bacteria and maintain the effectiveness of cephalexin capsules and other antibacterial drugs, cephalexin capsules should be used only to treat infections that are proven or strongly suspected to be caused by bacteria

Respiratory Tract Infections Cephalexin capsules are indicated for the treatment of respiratory tract infections caused by susceptible isolates of Streptococcus pneumoniae and Streptococcus pyogenes

Otitis Media Cephalexin capsules are indicated for the treatment of otitis media caused by susceptible isolates of Streptococcus pneumoniae , Haemophilus influenzae , Staphylococcus aureus , Streptococcus pyogenes , and Moraxella catarrhalis

Skin and Skin Structure Infections Cephalexin capsules are indicated for the treatment of skin and skin structure infections caused by susceptible isolates of the following Gram-positive bacteria: Staphylococcus aureus and Streptococcus pyogenes

Bone Infections Cephalexin capsules are indicated for the treatment of bone infections caused by susceptible isolates of Staphylococcus aureus and Proteus mirabilis

Genitourinary Tract Infections Cephalexin capsules are indicated for the treatment of genitourinary tract infections, including acute prostatitis, caused by susceptible isolates of Escherichia coli , Proteus mirabilis , and Klebsiella pneumoniae

Usage To reduce the development of drug-resistant bacteria and maintain the effectiveness of cephalexin capsules and other antibacterial drugs, cephalexin capsules should be used only to treat infections that are proven or strongly suspected to be caused by susceptible bacteria. When culture and susceptibility information is available, this information should be considered in selecting or modifying antibacterial therapy. In the absence of such data, local epidemiology and susceptibility patterns may contribute to the empiric selection of therapy.

250 mg capsules : Dark green opaque/white size “2” hard gelatin capsule filled with off white granular powder and imprinted with “A 42” on dark green opaque cap and “250 mg” on white body with black ink. 500 mg capsules : Dark green opaque/light green opaque size “0” hard gelatin capsule filled with off white granular powder and imprinted with “A 43” on dark green opaque cap and “500 mg” on light green opaque body with black ink. Capsules: 250 mg and 500 mg

Adults and patients at least 15 years of age The usual dose is 250 mg every 6 hours, but a dose of 500 mg every 12 hours may be administered Pediatric patients (over 1 year of age) Otitis media: 75 to 100 mg/kg in equally divided doses every 6 hours All other indications: 25 to 50 mg/kg given in equally divided doses In severe infections: 50 to 100 mg/kg may be administered in equally divided doses Duration of therapy ranges from 7 to 14 days depending on the infection type and severity. Dosage adjustment is required in patients with severe and end stage renal disease (ESRD) defined as creatinine clearance below 30 mL/min

Adults and Pediatric Patients at Least 15 Years of Age The usual dose of oral cephalexin capsules is 250 mg every 6 hours, but a dose of 500 mg every 12 hours may be administered. Treatment is administered for 7 to 14 days. For more severe infections larger doses of oral cephalexin capsules may be needed, up to 4 grams daily in two to four equally divided doses

Pediatric Patients (over 1 year of age) The recommended total daily dose of oral cephalexin capsules for pediatric patients is 25 to 50 mg/kg given in equally divided doses for 7 to 14 days. In the treatment of β-hemolytic streptococcal infections, duration of at least 10 days is recommended. In severe infections, a total daily dose of 50 to 100 mg/kg may be administered in equally divided doses. For the treatment of otitis media, the recommended daily dose is 75 to 100 mg/kg given in equally divided doses

Dosage Adjustments in Adult and Pediatric Patients at Least 15 Years of Age with Renal Impairment Administer the following dosing regimens for cephalexin capsules to patients with renal impairment . Table 1. Recommended Dose Regimen for Patients with Renal Impairment *There is insufficient information to make dose adjustment recommendations in patients on hemodialysis. Renal function Dose regimen recommendation Creatinine clearance > 60 mL/min No dose adjustment Creatinine clearance 30 to 59 mL/min No dose adjustment; maximum daily dose should not exceed 1g Creatinine clearance 15 to 29 mL/min 250 mg, every 8 hours or every 12 hours Creatinine clearance 5 to 14 mL/min not yet on dialysis* 250 mg, every 24 hours Creatinine clearance 1 to 4 mL/min not yet on dialysis* 250 mg, every 48 hours or every 60 hours

Serious hypersensitivity (anaphylactic) reactions : Prior to use, inquire regarding history of hypersensitivity to beta-lactam antibacterial drugs. Discontinue the drug if signs or symptoms of an allergic reaction occur and institute supportive measures. Clostridium difficile -associated diarrhea (CDAD ): Evaluate if diarrhea occurs. Direct Coombs’ Test Seroconversion : If anemia develops during or after cephalexin therapy, evaluate for drug-induced hemolytic anemia. Seizure Potential : Use lower dose in patients with renal impairment. 5.1 Hypersensitivity Reactions Allergic reactions in the form of rash, urticaria, angioedema, anaphylaxis, erythema multiforme, Stevens-Johnson syndrome, or toxic epidermal necrolysis have been reported with the use of cephalexin. Before therapy with cephalexin is instituted, inquire whether the patient has a history of hypersensitivity reactions to cephalexin, cephalosporins, penicillins, or other drugs. Cross-hypersensitivity among beta-lactam antibacterial drugs may occur in up to 10% of patients with a history of penicillin allergy. If an allergic reaction to cephalexin occurs, discontinue the drug and institute appropriate treatment

Clostridium difficile -Associated Diarrhea Clostridium difficile - associated diarrhea (CDAD) has been reported with use of nearly all antibacterial agents, including cephalexin, and may range in severity from mild diarrhea to fatal colitis. Treatment with antibacterial agents alters the normal flora of the colon leading to overgrowth of C. difficile . C. difficile produces toxins A and B, which contribute to the development of CDAD. Hypertoxin-producing strains of C. difficile cause increased morbidity and mortality, as these infections can be refractory to antimicrobial therapy and may require colectomy. CDAD must be considered in all patients who present with diarrhea following antibiotic use. Careful medical history is necessary since CDAD has been reported to occur over two months after the administration of antibacterial agents. If CDAD is suspected or confirmed, ongoing antibiotic use not directed against C. difficile may need to be discontinued. Appropriate fluid and electrolyte management, protein supplementation, antibiotic treatment of C. difficile , and surgical evaluation should be instituted as clinically indicated

Direct Coombs’ Test Seroconversion Positive direct Coombs’ tests have been reported during treatment with the cephalosporin antibacterial drugs including cephalexin. Acute intravascular hemolysis induced by cephalexin therapy has been reported. If anemia develops during or after cephalexin therapy, perform a diagnostic work-up for drug-induced hemolytic anemia, discontinue cephalexin and institute appropriate therapy

Seizure Potential Several cephalosporins have been implicated in triggering seizures, particularly in patients with renal impairment when the dosage was not reduced. If seizures occur, discontinue cephalexin. Anticonvulsant therapy can be given if clinically indicated

Prolonged Prothrombin Time Cephalosporins may be associated with prolonged prothrombin time. Those at risk include patients with renal or hepatic impairment, or poor nutritional state, as well as patients receiving a protracted course of antibacterial therapy, and patients receiving anticoagulant therapy. Monitor prothrombin time in patients at risk and manage as indicated

Development of Drug-Resistant Bacteria Prescribing cephalexin in the absence of a proven or strongly suspected bacterial infection is unlikely to provide benefit to the patient and increases the risk of the development of drug-resistant bacteria. Prolonged use of cephalexin may result in the overgrowth of nonsusceptible organisms. Careful observation of the patient is essential. If superinfection occurs during therapy, appropriate measures should be taken.

Metformin: increased metformin concentrations. Monitor for hypoglycemia. Probenecid-The renal excretion of cephalexin is inhibited by probenecid. Co-administration of probenecid with cephalexin is not recommended. Administration of cephalexin may result in a false-positive reaction glucose in the urine

Metformin Administration of cephalexin with metformin results in increased plasma metformin concentrations and decreased renal clearance of metformin. Careful patient monitoring and dose adjustment of metformin is recommended in patients concomitantly taking cephalexin and metformin

Probenecid The renal excretion of cephalexin is inhibited by probenecid. Co-administration of probenecid with cephalexin is not recommended

Interaction with Laboratory or Diagnostic Testing A false-positive reaction may occur when testing for the presence of glucose in the urine using Benedict’s solution or Fehling’s solution.