Keflex

Keflex

cefalexin

Manufacturer:

DKSH

Distributor:

DKSH
Full Prescribing Info
Contents
Cephalexin monohydrate.
Description
Each capsule contains cephalexin monohydrate equivalent to 250 or 500 mg of cephalexin. After mixing, each 5 mL of cephalexin, for oral suspension, will contain cephalexin monohydrate equivalent to 125 mg of cephalexin. The pediatric drops contain 100 mg cephalexin monohydrate/mL.
Cephalexin is 7-(D-α-amino-α-phenylacetamido)-3-methyl-3-cephem-4-carboxylic acid, monohydrate.
The nucleus of cephalexin is related to that of other cephalosporin antibiotics. The compound is a zwitterion; ie the molecule contains both a basic and an acidic group. The isoelectric point of cephalexin in water is approximately 4.5-5.
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 has a D-phenylglycyl group as substituent at the 7-amino position and an unsubstituted methyl group at the 3-position.
Action
A semisynthetic cephalosporin antibiotic.
Microbiology: In vitro tests demonstrate that the cephalosporins are bactericidal because of their inhibition of cell wall synthesis. Cephalexin is active against the following organisms in vitro: β-Haemolytic streptococci; Staphylococci, including coagulase-positive, coagulase-negative and penicillinase-producing strains; Streptococcus (Diplococcus) pneumoniae; Escherichia coli; Proteus mirabilis; Klebsiella sp, Haemophilus influenzae; Moraxella (Branhamella) catarrhalis.
Note: Most strains of enterococci (Enterococcus faecalis [formerly Streptococcus faecalis]) and a few strains of staphylococci are resistant to cephalexin. It is not active against most strains of Enterobacter sp, Morganella morganii (formerly Proteus morganii) and Proteus vulgaris. It has no activity against Pseudomonas or Acinetobacter calcoaceticus (formerly Mima and Herellea sp). When tested by in vitro methods, staphylococci exhibit cross-resistance between cephalexin and methicillin-type antibiotics.
Susceptibility Testing: Quantitative methods that require measurement of zone diameters give the most precise estimates of antibiotics susceptibility. One such procedure has been recommended for use with disks for testing susceptibility to cephalothin. Interpretations correlate zone diameters of the disk test with MIC values of cephalexin. With this procedure, a report from the laboratory of "resistant" indicates that the infecting organism is not likely to respond to therapy. A report of "intermediate susceptibility" suggests that the organism would be susceptible if the infection is confined to the urine, in which high antibiotic levels can be obtained, or if high dosage is used in other types of infection.
Pharmacokinetics: Cephalexin is 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 mg/L, respectively, were obtained at 1 hr. Measurable levels were present 6 hrs after administration. Cephalexin is excreted in the urine by glomerular filtration and tubular secretion. Studies showed that >90% of the drug was excreted unchanged in the urine within 8 hrs. During this period, peak urine concentrations following the 250-mg, 500-mg and 1-g doses were approximately 1000, 2200 and 5000 mg/L, respectively.
Indications/Uses
Treatment of the following infections when caused by susceptible strains of the designated microorganisms:
Bacterial sinusitis caused by Streptococci, S. pneumoniae and Staphylococcus aureus (methicillin-sensitive only).
Respiratory tract infections caused by S. pneumoniae and group A β-haemolytic Streptococci. (Penicillin is the usual drug of choice in the treatment and prevention of streptococcal infections, including the prophylaxis of rheumatic fever. Cephalexin is generally effective in the eradication of streptococci from the nasopharynx; however, substantial data establishing the efficacy of cephalexin in the subsequent prevention of rheumatic fever are not available at present.)
Otitis media due to S. pneumoniae, H. influenzae, staphylococci, streptococci and M. catarrhalis.
Skin and soft tissue infections caused by staphylococci and/or streptococci.
Bone infections caused by staphylococci and/or P. mirabilis.
Genitourinary tract infections, including acute prostatitis, caused by E. coli, P. mirabilis and Klebsiella sp.
Dental infections caused by staphylococci and/or streptococci.
Note: Culture and susceptibility tests should be initiated prior to and during therapy. Renal function studies should be performed when indicated.
Dosage/Direction for Use
Cephalexin is administered orally.
Adults: The adult dosage ranges from 1-4 g daily in divided doses. Usual Dose: 250 mg every 6 hrs. For the following infections, a dosage of 500 mg may be administered every 12 hrs; streptococcal pharyngitis, skin and skin-structure infections, and uncomplicated cystitis in the patients >15 years. Cystitis therapy should be continued for 7-14 days. For more severe infections or those caused by less susceptible organisms, larger doses may be needed. If daily doses of cephalexin >4 g are required, parenteral cephalosporins, in appropriate doses, should be considered.
Children: Usual Recommended Daily Dosage: 25-50 mg/kg in equally divided doses. For streptococcal pharyngitis in patients >1 yr, mild, uncomplicated urinary tract infections, and for skin and skin-structure infections, the total daily dose may be divided and administered every 12 hrs (see table).

Click on icon to see table/diagram/image
In severe infections, the dosage may be doubled.
In the therapy of otitis media, clinical studies have shown that a dosage of 75-100 mg/kg/day in 4 divided doses is required.
In the treatment of β-haemolytic streptococcal infections, a therapeutic dosage of cephalexin should be administered for at least 10 days.
Overdosage
Symptoms: Symptoms of oral overdose may include nausea, vomiting, epigastric distress, diarrhea and hematuria. If other symptoms are present, it is probably secondary to an underlying disease state, an allergic reaction or toxicity due to ingestion of a 2nd medication.
Treatment: In managing overdosage, consider the possibility of multiple drug overdoses, interaction among drugs, and unusual drug kinetics in the patient.
Unless 5-10 times the normal dose of cephalexin has been ingested, gastrointestinal decontamination should not be necessary.
Protect the patient's airway and support ventilation and perfusion. Meticulously monitor and maintain, within acceptable limits, the patient's vital signs, blood gases, serum electrolytes, etc. Absorption of drugs from the gastrointestinal tract may be decreased by giving activated charcoal, which in many cases, is more effective than emesis or lavage; consider charcoal instead of or in addition to gastric emptying. Repeated doses of charcoal over time may hasten elimination of some drugs that have been absorbed. Safeguard the patient's airway when employing gastric emptying or charcoal.
Forced diuresis, peritoneal dialysis, hemodialysis or charcoal hemoperfusion have not been established as beneficial for an overdose of cephalexin; however, it would be extremely unlikely that one of these procedures would be indicated.
The oral LD50 of cephalexin in rats is 5000 mg/kg.
Contraindications
Patients with known allergy to the cephalosporin group of antibiotics.
Warnings
Before cephalexin therapy is instituted, careful inquiry should be made concerning previous hypersensitivity reactions to cephalosporin and penicillin. Cephalosporin C derivatives should be given cautiously to penicillin-sensitive patients.
Serious acute hypersensitivity reactions may require epinephrine and other emergency measures.
There are some clinical and laboratory evidence of partial cross-allergenicity of the penicillins and the cephalosporins. Patients have been reported to have had severe reactions (including anaphylaxis) to both drugs.
Any patient who has demonstrated some form of allergy, particularly to drugs, should receive antibiotics cautiously. No exception should be made with regard to cephalexin.
Pseudomembranous colitis has been reported with virtually all broad-spectrum antibiotics (including macrolides, semi-synthetic penicillins and cephalosporins); therefore, it is important to consider its diagnosis in patient who develop diarrhea in association with the use of antibiotics. Such colitis may range in severity from mild to life-threatening. Mild cases of pseudomembranous colitis usually respond to drug discontinuance alone. In moderate to severe cases, appropriate measures should be taken.
Special Precautions
General: Patients should follow carefully so that any side effects or unusual manifestations of drug idiosyncrasy may be detected. If an allergic reaction to cephalexin occurs, the drug should be discontinued and the patient treated with the usual agents (eg, epinephrine or other pressor amines, antihistamines or corticosteroids).
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.
Positive direct Coombs' tests have been reported during treatment with the cephalosporin antibiotics. In hematologic studies or in transfusion cross-matching procedure when antiglobulin tests are performed on the minor side or in Coombs' testing of newborns whose mothers have received cephalosporin antibiotics before parturition, it should be recognized that a positive Coombs' test may be due to the drug.
Cephalexin should be administered with caution in the presence of markedly impaired renal function. Under such condition, careful clinical and laboratory studies should be made because safe dosage may be lower than that usually recommended.
Indicated surgical procedures should be performed in conjunction with antibiotic therapy.
As a result of administration of cephalexin, a false-positive reaction for glucose in the urine may occur. This has been observed with Benedict's and Fehling's solutions and also with Clinitest tablets but not with Tes-Tape (Glucose Enzymatic Test Strip, USP, Lilly).
Broad-spectrum antibiotics should be prescribed with caution in individuals with a history of gastrointestinal disease, particularly colitis.
Use in pregnancy: The daily oral administration of cephalexin to rats in doses of 250 or 500 mg/kg prior to and during pregnancy, or to rats and mice during the period of organogenesis only, had no adverse effects on fertility, fetal viability, fetal weight or litter size. Note that the safety of cephalexin during pregnancy in humans has not been established.
Cephalexin showed no enhanced toxicity in weaning and newborn rats as compared with adult animals. Nevertheless, because the studies in humans cannot rule out the possibility of harm, cephalexin should be used during pregnancy only if clearly needed.
Use in lactation: The excretion of cephalexin in the milk increased up to 4 hrs after a 500-mg dose: The drug reached a maximum level of 4 mg/L, then decreased gradually, and had disappeared 8 hrs after administration. Caution should be exercised when cephalexin is administered to a nursing woman.
Use In Pregnancy & Lactation
Use in pregnancy: The daily oral administration of cephalexin to rats in doses of 250 or 500 mg/kg prior to and during pregnancy, or to rats and mice during the period of organogenesis only, had no adverse effects on fertility, fetal viability, fetal weight or litter size. Note that the safety of cephalexin during pregnancy in humans has not been established.
Cephalexin showed no enhanced toxicity in weaning and newborn rats as compared with adult animals. Nevertheless, because the studies in humans cannot rule out the possibility of harm, cephalexin should be used during pregnancy only if clearly needed.
Use in lactation: The excretion of cephalexin in the milk increased up to 4 hrs after a 500-mg dose: The drug reached a maximum level of 4 mg/L, then decreased gradually, and had disappeared 8 hrs after administration. Caution should be exercised when cephalexin is administered to a nursing woman.
Adverse Reactions
Gastrointestinal: Symptoms of pseudomembranous colitis may appear either during or after antibiotic treatment. Nausea and vomiting have been reported rarely. The most frequent adverse effects has been diarrhea. It was very rarely severe enough to warrant cessation of therapy. Dyspepsia and abdominal pain have also occurred. As with some penicillins and some other cephalosporins, transient hepatitis and cholestatic jaundice have been reported rarely.
Hypersensitivity: Allergic reactions in the form of rash, urticaria, angioedema and rarely, erythema multiforme. Stevens-Johnson syndrome or toxic epidermal necrolysis have been observed. These reactions usually subside upon discontinuation of the drug. Anaphylaxis has also been reported.
Other reactions have included genital and anal pruritus, genital moniliasis, vaginitis and vaginal discharge, dizziness, fatigue, headache, agitation, confusion, hallucinations, arthralgia, arthritis and joint disorders. Reversible interstitial nephritis has been reported rarely. Eosinophilia, neutropenia, thrombocytopenia and slight elevations in SGOT and SGPT have been reported.
Caution For Usage
Shake well before using and keep tightly closed.
Storage
Keep capsules tightly closed and store at controlled room temperature, 59-86°F (15-30°C).
After mixing the suspension, store in a refrigerator. It may be kept for 14 days without significant loss of potency.
MIMS Class
ATC Classification
J01DB01 - cefalexin ; Belongs to the class of first-generation cephalosporins. Used in the systemic treatment of infections.
Presentation/Packing
Cap 250 mg x 100's. 500 mg x 100's. Susp 125 mg/5 mL x 60 mL.
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