PRECAUTIONS
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 KEFLEX. Before
therapy with KEFLEX 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 KEFLEX 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
KEFLEX, 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 KEFLEX. 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 KEFLEX 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 KEFLEX 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.
Nonclinical Toxicology
Carcinogenesis, Mutagenesis, Impairment Of Fertility
Lifetime studies in animals have not been performed to
evaluate the carcinogenic potential of cephalexin. Tests to determine the
mutagenic potential of cephalexin have not been performed. In male and female
rats, fertility and reproductive performance were not affected by cephalexin
oral doses up to 1.5 times the highest recommended human dose based upon body
surface area.
Use In Specific Populations
Pregnancy
Pregnancy Category B
There are no adequate and well-controlled studies in
pregnant women. Because animal reproduction studies are not always predictive
of human response, this drug should be used during pregnancy only if clearly
needed.
Reproduction studies have been performed on mice and rats
using oral doses of cephalexin monohydrate 0.6 and 1.5 times the maximum daily
human dose (66 mg/kg/day) based upon body surface area basis, and have revealed
no evidence of impaired fertility or harm to the fetus.
Nursing Mothers
Cephalexin is excreted in human milk. Caution should be
exercised when KEFLEX is administered to a nursing woman.
Pediatric Use
The safety and effectiveness of KEFLEX in pediatric
patients was established in clinical trials for the dosages described in the
dosage and administration section [see DOSAGE AND ADMINISTRATION].
Geriatric Use
Of the 701 subjects in 3 published clinical studies of
cephalexin, 433 (62%) were 65 and over. No overall differences in safety or
effectiveness were observed between these subjects and younger subjects, and
other reported clinical experience has not identified differences in responses
between the elderly and younger patients.
This drug is substantially excreted by the kidney, and
the risk of toxic reactions to this drug may be greater in patients with
impaired renal function. Because elderly patients are more likely to have
decreased renal function, care should be taken in dose selection [see WARNINGS
AND PRECAUTIONS].
Renal Impairment
KEFLEX should be administered with caution in the
presence of impaired renal function (creatinine clearance < 30 mL/min, with
or without dialysis). Under such conditions, careful clinical observation and
laboratory studies renal function monitoring should be conducted because safe
dosage may be lower than that usually recommended [see DOSAGE AND
ADMINISTRATION].
REFERENCES
1. Clinical and Laboratory Standards Institute (CLSI).
Methods for Dilution Antimicrobial Susceptibility Tests for Bacteria that Grow
Aerobically; Approved Standard - Tenth Edition. CLSI document M07-A10, Clinical
and Laboratory Standards Institute, 950 West Valley Road, Suite 2500, Wayne,
Pennsylvania 19087, USA, 2015.
2. Clinical and Laboratory Standards Institute (CLSI).
Performance Standards for Antimicrobials Susceptibility Tests; Twenty-Fifth
Informational Supplement. CLSI document M100-S25, Clinical and Laboratory
Standards Institute, 950 West Valley Road, Suite 2500, Wayne, Pennsylvania
19087, USA, 2015.
3. Clinical and Laboratory Standards Institute (CLSI).
Performance Standards for Antimicrobial Disk Susceptibility Tests; Approved
Standard - Twelfth Edition. CLSI document M02-A12, Clinical and Laboratory
Standards Institute, 950 West Valley Road, Suite 2500, Wayne, Pennsylvania
19087, USA, 2015.