Cefalexin


Concise Prescribing Info
Indications/Uses
Listed in Dosage.
Dosage/Direction for Use
Adult : PO Skin and soft tissue infections; Uncomplicated urinary tract infections 250 mg 6 hourly or 500 mg 12 hourly. Max: 4,000 mg/day in 2-4 divided doses. Respiratory tract infections; Bone and joint infections; Genitourinary infections; Acute prostatitis; Acute dental infections 1,000-4,000 mg/day in divided doses; most infections respond to 500 mg 8 hourly. Streptococcal pharyngitis 250 mg 6 hourly or 500 mg 12 hourly for at least 10 days. Max: 4,000 mg/day in divided doses.
Dosage Details
Oral
Skin and soft tissue infections, Uncomplicated urinary tract infections
Adult: 250 mg 6 hourly or 500 mg 12 hourly. Max: 4,000 mg daily in 2-4 divided doses.
Child: 25-50 mg/kg daily in divided doses administered 12 hourly.

Oral
Acute dental infections, Acute prostatitis, Bone and joint infections, Genitourinary infections, Respiratory tract infections
Adult: 1,000-4,000 mg daily in divided doses; most infections respond to 500 mg 8 hourly.
Child: <5 years 125 mg 8 hourly; ≥5 years 250 mg 8 hourly. Dose may be doubled in severe infections. Usual dose: 25-50 mg/kg daily in divided doses.

Oral
Streptococcal pharyngitis
Adult: 250 mg 6 hourly or 500 mg 12 hourly for at least 10 days. Max: 4,000 mg daily in divided doses.
Child: 25-50 mg/kg daily in divided doses administered 12 hourly for at least 10 days.

Oral
Otitis media
Child: 75-100 mg/kg daily in 4 divided doses.
Renal Impairment
Dose reduction may be required. Refer to detailed product guideline.
Administration
May be taken with or without food. May be taken w/ meals to reduce GI discomfort.
Reconstitution
Powder for oral susp: Invert and tap the bottle to loosen the powder. In 2 portions, add the amount of water specified on the bottle then shake well after each addition until suspended.
Contraindications
Hypersensitivity to cephalosporins. Acute porphyria.
Special Precautions
Patients with history of carbapenem or penicillin allergy (especially IgE-mediated reactions), and seizure disorder. Children. Renal impairment. Pregnancy and lactation.
Adverse Reactions
Significant: Hypersensitivity (rash, urticaria, angioedema, erythema multiforme, Stevens-Johnson syndrome, toxic epidermal necrolysis), diarrhoea, pseudomembranous colitis, positive Coombs’ test, seizures (in patient with renal impairment), acute intravascular haemolysis, elevated INR.
Blood and lymphatic system disorders: Eosinophilia, neutropenia, thrombocytopenia, haemolytic anaemia.
Gastrointestinal disorders: Dyspepsia, abdominal pain, gastritis, nausea, vomiting.
General disorders and administration site conditions: Fatigue, fever.
Hepatobiliary disorders: Rarely, transient hepatitis, cholestatic jaundice.
Investigations: Slightly elevated AST and ALT.
Musculoskeletal and connective tissue disorders: Arthralgia, arthritis.
Nervous system disorders: Headache, dizziness.
Psychiatric disorders: Agitation, confusion, hallucinations, nervousness, hyperactivity.
Renal and urinary disorders: Interstitial nephritis (reversible).
Reproductive system and breast disorders: Genital and anal pruritus, vaginitis, genital moniliasis and candidiasis, vaginal discharge.
Potentially Fatal: Anaphylaxis, Clostridium difficile-associated diarrhoea (CDAD).
MonitoringParameters
Monitor renal function tests, LFTs, and CBC periodically with prolonged therapy; monitor for signs of anaphylaxis during 1st dose. Monitor prothrombin time with patient at risk (e.g. nutritionally-deficient patients, prolonged treatment, hepatic or renal impairment).
Overdosage
Symptoms: Nausea, vomiting, epigastric distress, diarrhoea and haematuria. Management: Symptomatic and supportive treatment.
Drug Interactions
Renal excretion may be inhibited by probenecid resulting to increased plasma concentration of cefalexin. May increase plasma concentration of metformin. Increased risk of nephrotoxicity with amphotericin, loop diuretics, aminoglycoside, capreomycin or vancomycin. May increase risk of hypokalaemia with gentamicin (in patient taking cytotoxic drugs for leukaemia). May decrease efficacy of oestrogen-containing oral contraceptives.
Food Interaction
Slightly reduced and delayed absorption with food.
Lab Interference
Positive direct Coombs’ test. May result to false-positive reaction for urine glucose with Benedict’s solution, Fehling’s solution, or copper sulfate test tablets; false-positive serum or urine creatinine with Jaffé reaction; false-positive urinary proteins and steroids.
Action
Description: Cefalexin, a 1st generation oral cephalosporin, binds to 1 or more of the penicillin-binding proteins (PBPs) which in turn blocks the final transpeptidation step of peptidoglycan synthesis in bacterial cell wall, thus inhibiting its biosynthesis and arresting cell wall assembly resulting to bacterial lysis.
Pharmacokinetics:
Absorption: Rapidly and almost completely absorbed from the gastrointestinal tract. Slightly reduced and delayed absorption with food. Time to peak plasma concentration: Approx 1 hour.
Distribution: Widely distributed into most body tissues and fluids (e.g. gallbladder, liver, kidneys, bone, sputum, bile, pleural and synovial fluids) except CSF. Crosses placenta and enters breast milk (small amounts). Plasma protein binding: Approx 6-15%.
Metabolism: Not metabolised.
Excretion: Via urine (approx 80-100% as unchanged drug). Elimination half-life: 0.5-1.2 hours.
Chemical Structure

Chemical Structure Image
Cefalexin

Source: National Center for Biotechnology Information. PubChem Database. Cephalexin, CID=27447, https://pubchem.ncbi.nlm.nih.gov/compound/Cephalexin (accessed on Jan. 21, 2020)

Storage
Cap/tab: Store between 20-25°C. Powder for oral susp: Store between 20-25°C. Refrigerate at 2-8°C after reconstitution; discard after 14 days.
MIMS Class
ATC Classification
J01DB01 - cefalexin ; Belongs to the class of first-generation cephalosporins. Used in the systemic treatment of infections.
References
Anon. Cephalexin. Lexicomp Online. Hudson, Ohio. Wolters Kluwer Clinical Drug Information, Inc. https://online.lexi.com. Accessed 01/07/2019.

Buckingham R (ed). Cefalexin. Martindale: The Complete Drug Reference [online]. London. Pharmaceutical Press. https://www.medicinescomplete.com. Accessed 01/07/2019.

Cephalexin - Capsule, Powder for Suspension, Tablet (Teva Pharmaceuticals USA, Inc.). DailyMed. Source: U.S. National Library of Medicine. https://dailymed.nlm.nih.gov/dailymed/. Accessed 07/10/2014.

Cephalexin Capsules/Tablets/Granules for Oral Suspension (Malaysian Pharmaceutical Industries Sdn. Bhd.). National Pharmaceutical Regulatory Agency - Ministry of Health Malaysia. https://www.npra.gov.my/. Accessed 01/07/2019.

Disclaimer: This information is independently developed by MIMS based on Cefalexin from various references and is provided for your reference only. Therapeutic uses, prescribing information and product availability may vary between countries. Please refer to MIMS Product Monographs for specific and locally approved prescribing information. Although great effort has been made to ensure content accuracy, MIMS shall not be held responsible or liable for any claims or damages arising from the use or misuse of the information contained herein, its contents or omissions, or otherwise. Copyright © 2020 MIMS. All rights reserved. Powered by MIMS.com
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