Professional Information — Cephalexin 250 Mg

Indications and Usage

Cephalexin tablets are indicated for the treatment of the following infections when caused by susceptible strains of the designated microorganisms:

Respiratory tract infections caused by susceptible isolates of Streptococcus pneumoniae and Streptococcus pyogenes

Otitis media due to susceptible isolates of Streptococcu pneumoniae, Haemophilus influenzae, Staphylococcus aureus, Streptococcus pyogenes, and Moraxella Catarrhalis.

Skin and skin structure infections caused by susceptible isolates of the following Gram-positive bacteria: Staphylococcus aureus, and Streptococcus pyogenes.

Bone infections caused by susceptible isolates of Staphylococcus aureus and Proteus Mirabilis.

Genitourinary tract infections, including acute prostatitis, caused by susceptible isolates of Escherichia coli, Proteus mirabilis, and Klebsiella pneumoniare.

To reduce the development of drug-resistant bacteria and maintain the effectiveness of cephalexin tablets and other antibacterial drugs, cephalexin tablets should be used only to treat or prevent infections that are proven or strongly suspected to be caused by susceptible bacteria. When culture and susceptibility information are available, they 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.

Dosage and Administration

Cephalexin tablets are administered orally.

Adults and Pediatric 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.  Treatment is administered for 7 to 14 days. For more severe infections larger doses of oral cephalexin may be needed, up to 4 grams in two to four equally divided doses.

Pediatric Patients (over 1 year of age)

The recommended total daily dose of oral cephalexin for pediatric patients is 25 to 50 mg/kg 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.

In the treatment of otitis media, the recommended daily dose is 75 to 100 mg/kg/day in equally divided doses.

Dosage adjustments in Adults and Pediatric Patients at Least 15 years of Age with Renal Impairment

Administer the following dosing regimens for cephalexin tablets to patients with renal impairment (see PRECAUTIONS ).

Contraindications

Cephalexin tablets are contraindicated in patients with known allergy to cephalexin or other members of the cephalosporin class of antibacterial drugs.

Adverse Reactions

Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in practice. The most frequent adverse reaction was diarrhea. Nausea and vomiting, dyspepsia, gastritis, and abdominal pain have also occurred. As with penicillins and other cephalosporins, transient hepatitis and cholestatic jaundice have been reported.

Other reactions have included hypersensitivity reactions, genital and anal pruritus, genital candidiasis, vaginitis and vaginal discharge, dizziness, fatigue, headache, agitation, confusion, hallucinations, arthralgia, arthritis, and joint disorder. Reversible interstitial nephritis has been reported. Eosinophilia, neutropenia, thrombocytopenia, hemolytic anemia, and slight elevations in aspartate transaminase (AST) and alanine transaminase (ALT) have been reported.

In addition to the adverse reactions listed above that have been observed in patients treated with cephalexin tablets, the following adverse reactions and other altered laboratory tests have been reported for cephalosporin class antibacterial drugs:

Other Adverse Reactions: Fever, colitis, aplastic anemia, hemorrhage, renal dysfunction, and toxic nephropathy.

Altered Laboratory Tests: Prolonged prothrombin time, increased blood urea nitrogen (BUN), increased creatinine, elevated alkaline phosphatase, elevated bilirubin, elevated lactate dehydrogenase (LDH), pancytopenia, leukopenia, and agranulocytosis.

Drug Interactions

Metformin: Administration of cephalexin tablets 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 tablets and metformin (see CLINICAL  PHARMACOLOGY ).

Probenecid: The renal excretion of cephalexin tablets is inhibited by probenecid. Coadministration of probenecid with cephalexin tablets is not recommended.

Drug/laboratory Test Interactions: A false-positive reaction may occur when testing for the presence of glucose in the urine using Benedict's solution or Fehling's solutions.

Overdosage

Symptoms of oral overdose may include nausea, vomiting, epigastric distress, diarrhea, and hematuria. In the event of an overdose, institute general supportive measures.

Forced diuresis, peritoneal dialysis, hemodialysis, or charcoal hemoperfusion have not been established as beneficial for an overdose of cephalexin.

Description

Cephalexin tablets, USP contain the active ingredient cephalexin, which is a semisynthetic cephalosporin antibiotic intended for oral administration. It is 7-(D-α- amino-α-phenylacetamido)-3-methyl-3-cephem-4-carboxylic acid, monohydrate.

Cephalexin, USP has the molecular formula C₁₆H₁₇N₃O₄S•H₂O and the molecular weight is 365.40. Cephalexin, USP has the following structural formula:

The nucleus of cephalexin is related to that of other cephalosporin antibiotics. The compound is a zwitterion; i.e., the molecule contains both a basic and an acidic group. The isoelectric point of cephalexin in water is approximately 4.5 to 5.

The crystalline form of cephalexin which is available is a monohydrate. It is a white crystalline solid having a bitter taste. Solubility in water is low at room temperature; 1 or 2 mg/mL may be dissolved readily, but higher concentrations are obtained with increasing difficulty.

The cephalosporins differ from penicillins in the structure of the bicyclic ring system.

Cephalexin, USP has a D-phenylglycyl group as substituent at the 7-amino position and an unsubstituted methyl group at the 3-position.

Each tablet contains cephalexin monohydrate equivalent to 250 mg or 500 mg of cephalexin. The tablets also contain magnesium stearate, microcrystalline cellulose, polyethylene glycol, sodium starch glycolate, and titanium dioxide. In addition, the 250 mg contains hypromellose and polysorbate 80. The 500 mg contains polyvinyl alcohol-part hydrolyzed and talc.

Clinical Pharmacology

Human Pharmacology

Cephalexin tablets are acid stable and may be given without regard to meals. It is rapidly absorbed after oral administration. Following doses of 250 mg, 500 mg, and 1 g, average peak serum levels of approximately 9, 18, and 32 mcg/mL, respectively, were obtained at 1 hour. Serum levels were detectable 6 hours after administration (at a level of detection of 0.2 mcg/mL). Cephalexin is approximately 10% to 15% bound to plasma proteins. Cephalexin is excreted in the urine by glomerular filtration and tubular secretion. Studies showed that over 90% of the drug was excreted unchanged in the urine within 8 hours. During this period, peak urine concentrations following the 250 mg, 500 mg, and 1 g doses were approximately 1,000, 2,200, and 5,000 mcg/mL, respectively.

In healthy subjects given single 500 mg doses of cephalexin and metformin, plasma metformin mean C_max and AUC increased by an average of 34% and 24%, respectively, and metformin mean renal clearance decreased by 14%. No information is available about the interaction of cephalexin and metformin following multiple doses of either drug.

Microbiology

Cephalexin is a bactericidal agent that acts by the inhibition of cell-wall synthesis.

Resistance

Methicillin-resistant staphylococci and most isolates of enterococci are resistant to cephalexin. Cephalexin is not active against most isolates of Enterobacter  spp., Morganella morganii, and Proteus vulqaris. Cephalexin has no activity against Pseudomonas spp., or Acinetobacter calcoaceticus. Penicillin-resistant Streptococcus pneumoniae is usually cross-resistant to beta-lactam antibacterial drugs.

Antimicrobial Activity

Cephalexin is active against most isolates of the following bacteria both in vitro and in clinical infections (see INDICATIONS AND USAGE ):

Gram-positive bacteria

Staphylococci aureus (methicillin-susceptible isolates only)

Streptococcus pneumoniae (penicillin-susceptible isolates)

Streptococcus pyogenes

Gram-negative bacteria

Escherichia coli

Haemophilus influenzae

Klebsiella pneumoniae

Moraxella catarrhalis

Proteus mirabilis

Susceptibility Testing

For specific information regarding susceptibility test interpretive criteria and associated test methods and quality control standards recognized by FDA for this drug, please see:  https://www.fda.gov/STIC.

How Supplied / Storage and Handling

Cephalexin tablets, USP are supplied as follows:

250 mg: bottles of 100 (NDC 0093-2238-01). Tablet identification number and color: white, capsule-shaped tablet, debossed “2238” on one side with a score between the “2” and the “3” and “TEVA” on the reverse side.

500 mg: bottles of 100 (NDC 0093-2240-01). Tablet identification number and color: white, capsule-shaped tablet, debossed “2240” on one side with a score between the “2” and the “4” and “TEVA” on the reverse side.

Store at 20° to 25°C (68° to 77°F) [see USP Controlled Room Temperature].

Dispense in a tight, light-resistant container as defined in the USP, with a child-resistant closure (as required). Keep tightly closed.

Keep this and all medications out of the reach of children.

Manufactured For:
Teva Pharmaceuticals
Parsippany, NJ 07054

Rev. B 10/2023

Patient Counseling Information

Advise patients that allergic reactions, including serious allergic reactions, could occur and that serious reactions require immediate treatment. Ask the patient about any previous hypersensitivity reactions to cephalexin tablets, other beta-lactams (including cephalosporins) or other allergens (see WARNINGS).

Diarrhea is a common problem caused by antibiotics which usually ends when the antibiotic is discontinued. Sometimes after starting treatment with antibiotics, patients can develop watery and bloody stools (with or without stomach cramps and fever) even as late as two or more months after having taken the last dose of the antibiotic. If this occurs, patients should contact their physician as soon as possible.

Patients should be counseled that antibacterial drugs including cephalexin tablets should only be used to treat bacterial infections. They do not treat viral infections (e.g., the common cold). When cephalexin tablets is prescribed to treat a bacterial infection, patients should be told that although it is common to feel better early in the course of therapy, the medication should be taken exactly as directed. Skipping doses or not completing the full course of therapy may (1) decrease the effectiveness of the immediate treatment and (2) increase the likelihood that bacteria will develop resistance and will not be treatable by Cephalexin tablets or other antibacterial drugs in the future.