Cephalexin is a 1st-generation cephalosporin antibiotic. The cephalosporins are bactericidal and similar to the penicillins, act by inhibiting synthesis of the bacterial cell wall.
It has good activity against a wide spectrum of gram-positive bacteria including penicillinase-producing, but not methicillin-resistant staphylococci; enterococci are however, resistant. Its activity against gram-negative bacteria is modest.
Pharmacokinetics: Absorption: Cephalexin is acid stable and is readily absorbed after oral administration. Food may delay absorption.
Blood Concentration: After an oral dose of 500 mg, peak serum concentrations of about 20 mcg/mL are attained in 1 hr; after IM dose of 1 g, serum concentration of about 20 mcg/mL in 1 hr is obtained; after IV dose of 1 g, serum concentration of about 50 mcg/mL in 15 min is obtained. Peak concentrations are subject to wide individual variation.
Metabolism: Serum half-life is about 0.5-2 hrs in patients with normal renal function and about 20 hrs in patients with severe renal failure. In newborn, it is 2.5-5 hrs.
Distribution: Widely distributed throughout the body. Maximum concentrations being reached in the liver and kidney; cephalexin does not accumulate following multiple doses. It does not enter the cerebrospinal fluid unless the meninges are inflammed but it does cross the placenta and is secreted in the milk. Six percent (6%) to 15% of the dose is bound to plasma proteins.
Excretion: About ≥80% of a dose is excreted in the urine in the first 6 hrs by glomerular filtration and tubular secretion, urinary concentrations >1 mg/mL have been achieved after dose of 500 mg. Probenecid delays urinary excretions and has been reported to increase biliary excretion. Therapeutically effective concentrations may be found in the bile.
Treatment of septicaemia, bone and joint infections, including burn wound infections, and urinary tract infections caused by susceptible bacterial organisms. Pharmaniaga Cephalexin is not effective in treating meningitis.
Used as a possible alternative to the penicillins for staphylococcus and nonenterococcal streptococcal infections including pneumonia, bone and joint infections, and bacterial endocarditis.
Adults: 1-2 g daily given in divided doses at 6, 8 or 12 hrly intervals.
Infants and Children: 25-100 mg/kg body weight daily in divided doses to a maximum of 4 g daily; 5-12 years 250 mg 3 times daily; 1-5 years 125 mg 3 times daily; <1 year 62.5-125 mg twice daily.
Administration: Take at regular intervals preferably between meals and complete the prescribed course as directed by the physician.
Oral Suspension: Directions for Reconstitution: Shake the bottle to loosen the powder. Add freshly boiled and cooled water, and shake well. Make up the volume to 60 mL. Use reconstituted suspension within 7 days. Shake the container well each time before use.
Signs and symptoms of oral overdosage may include nausea, vomiting, epigastric distress, diarrhea and hematuria.
Treatment: 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, with acceptable limits, the patients' 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 by employing gastric emptying or charcoal.
Forced diuresis, peritonial dialysis, hemodialysis or charcoal hemoperfusion have not been established as beneficial for overdosage of cephalexin; however, it would be extreme unlikely that one of these procedures would be indicated.
Known or suspected to be allergic to other cephalosporins should not be treated with cephalexin.
About 10% of penicillin-sensitive patients will also be allergic to cephalosporins and therefore, great care should be taken if cephalexin is given to patients known to be hypersensitive to penicillin.
Reduced dosage is recommended in patients with severe renal impairment.
The urine of patients taking cephalexin may give false positive reaction for glucose with copper reduction reagents. Positive results to the Coombs' test have been reported with cephalexin and these can interfere with blood-cross matching.
Use in pregnancy & lactation: Cephalexin crosses the placenta and small quantities are found in the milk of nursing mothers.
Cephalexin crosses the placenta and small quantities are found in the milk of nursing mothers.
Side effects of cephalexin include nausea, vomiting, diarrhea and abdominal discomfort. Allergic reactions eg, skin rashes, urticaria, eosinophilia, angioedema and anaphylaxis may occur, and rises in liver enzyme values have been noted.
Neutropenia has been reported. Suprainfection with resistant microorganisms, particularly candida, may follow treatment. There is the possibility of development of pseudomembranous colitis.
There have been isolated reports of cephalexin decreasing the efficacy of estrogen-containing oral contraceptives.
Concurrent treatment with high doses of cephalosporins and nephrotoxic drugs eg, aminoglycosides or potent diuretics (eg, frusemide, ethacrynic acid and piretamide) may adversely affect renal function.
Store below 25°C. Protect from light.
J01DB01 - cefalexin ; Belongs to the class of first-generation cephalosporins. Used in the systemic treatment of infections.
Cap 250 mg (pink/pink, size '2' hard gelatin, with characteristic markings) x 50 x 10's. 500 mg (white/pink, size '0' hard gelatin, with characteristic markings) x 50 x 10's. Oral susp 125 mg/5 mL (Before reconstitution: Orange coloured, free-flowing granules; After reconstitution: Orange coloured, sweet, viscous susp with a mixed fruit flavour) x 60 mL. 250 mg/5 mL (Before Reconstitution: Light yellow, free-flowing granules with a characteristic fruity fragrance; After Reconstitution: Light yellow, sweet, viscous susp with a characteristic fruity flavour) x 60 mL.