Cephalexin
Indications
Cephalexin is indicated for the treatment of the following infections when caused by susceptible organisms.
- Respiratory tract infections: Acute and chronic bronchitis and infected bronchiectasis.
- Genito-urinary tract infections: Acute and chronic nephritis, cystitis, urethritis and prostatitis, prophylaxis of recurrent urinary tract infections.
- Skin and soft tissue infections: Caused by staphylococci and/or streptococci.
- Ear, Nose and Throat infections: Otitis media, mastoiditis, sinusitis, follicular tonsillitis and pharyngitis.
- Bone infections: Caused by staphylococci and/or P. mirabilis.
Pharmacology
Cephalexin is a semisynthetic analogue of
Cephalosporin C. It kills bacteria by interfering in the synthesis of
the bacterial cell wall. Peptidoglycan is a heteropolymeric structure
that provides the cell wall with mechanical stability. The final stage
in the synthesis of peptidoglycan involves the completion of the
cross-linking and the terminal glycine residue of the Pentaglycine
Bridge is linked to the fourth residue of the pentapeptide (d-alanin).
The transpeptidase enzyme that performs this step is inhibited by
penicillins and cephalosporins. As a result the bacterial cell wall is
weakened, the cell swells and then ruptures. Cephalexin is a first
generation cephalosporin that is active by mouth.
Dosage & Administration
Adult:
Children's Weight Recommended Dose:
- The usual dose is 250 mg to 500 mg every 6 hour.
- For skin and soft tissue infections, streptococcal pharyngitis and uncomplicated cystitis, in patients over 15 years of age: 500 mg of the drug may be administered every 12 hour.
- In severe or deep seated infections the dose can be increased up to 3 g to 6 g daily.
Children's Weight Recommended Dose:
- 10 kg (22 Ibs): 62.5 mg to 125 mg qid or 125 mg to 250 mg bid
- 20 kg (44 Ibs): 125 mg to 250 mg qid or 250 mg to 500 mg bid
- 40 kg (88 Ibs): 250 mg to 500 mg qid or 500 mg to 1 g bid
Contraindications
Cephalen is contraindicated in patients with known hypersensitivity to the cephalosporin group of antibiotics.
Side Effects
Side effects include nausea, vomiting,
diarrhoea and abdominal discomfort. Symptoms of pseudomembranous colitis
may appear either during or after antibiotic treatment. Skin rash,
angio oedema, rise in serum aminotransferases, eosinophilia, neutropenia
have been reported very rarely. Superinfection with resistant micro
organisms, particularly candida may follow the treatment.
Pregnancy & Lactation
Pregnancy Category B. Cefalexin may be used
during pregnancy when it is considered essential. Cefalexin is found in
the milk of nursing mothers, hence caution should be taken when it is
administered to nursing mothers.
Precautions & Warnings
Cefalexin should be given with caution in
patients with renal impairment. Under such condition, careful clinical
observation should be made because safe dosage may be lower than the
usually recommended. The urine of patients receiving Cefalexin may give a
false positive reaction for glucose with copper reduction reagent.
Positive results to Coombs’ test have been reported. Although there is
no evidence of teratogenicity in animal tests, Cefalexin may be used
during pregnancy when it is considered essential. Cefalexin is found in
the milk of nursing mothers, hence caution should be taken when it is
administered to nursing mothers.
Therapeutic Class
First generation Cephalosporins
Storage Conditions
Should be stored in cool and dry place.
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