Oral Bone and joint infections, Dental infections, Genitourinary infections, Respiratory tract infections, Skin and soft tissue infections
Adult: Dose range: 1,000-4,000 mg daily in divided doses. Usual dose: 250 mg 6 hourly or 500 mg 12 hourly; higher doses may be given in more severe infections or those caused by less susceptible organisms. Treatment duration: 7-14 days depending on the type and severity of infection. Dosage or treatment recommendations may vary among countries and individual products. Refer to specific product guidelines. Child: Usual dose: 25-50 mg/kg daily in divided doses. Severe infections: 50-100 mg/kg daily in divided doses. Treatment duration: 7-14 days depending on the type and severity of infection (≥10 days for β-haemolytic streptococcal infections). Dosage or treatment recommendations may vary among countries and individual products. Refer to specific product guidelines.
Oral Otitis media
Child: 75-100 mg/kg daily in 4 divided doses.
Renal Impairment
Dosage adjustment may be required. Recommendations may vary among countries and individual products. Refer to specific product guidelines.
Administration
May be taken with or without food. May be taken w/ meals to reduce GI discomfort.
Reconstitution
Powder for oral susp: Reconstitute with an appropriate amount of water as specified on the container or bottle. Shake vigorously until suspended.
Contraindications
Hypersensitivity to cefalexin and other cephalosporins.
Special Precautions
Patient with history of penicillin allergy, history of gastrointestinal disease (particularly colitis), poor nutritional state, history of seizure disorder. Renal and hepatic impairment. Children. Pregnancy and lactation.
Adverse Reactions
Significant: Acute intravascular haemolysis, prolonged prothrombin time; overgrowth of nonsusceptible organisms (prolonged use), increased risk of seizures (high dose, particularly in patients with renal impairment). Blood and lymphatic system disorders: Eosinophilia, neutropenia, thrombocytopenia, haemolytic anaemia. Gastrointestinal disorders: Abdominal pain, diarrhoea, dyspepsia, gastritis, anal pruritus. Rarely, nausea, vomiting. General disorders and administration site conditions: Fatigue, fever. Hepatobiliary disorders: Rarely, transient hepatitis and cholestatic jaundice. Immune system disorders: Hypersensitivity reactions (e.g. rash, urticaria). Investigations: Slight elevations in AST and ALT. Musculoskeletal and connective tissue disorders: Arthralgia, arthritis, joint disorder, hypertonia. Nervous system disorders: Dizziness, headache. Psychiatric disorders: Agitation, confusion, hallucinations, nervousness, restlessness, sleep disturbance, hyperactivity. Renal and urinary disorders: Reversible interstitial nephritis. Reproductive system and breast disorders: Genital pruritus, genital candidiasis, vaginitis, vaginal discharge. Potentially Fatal: Serious hypersensitivity reactions including anaphylaxis and severe cutaneous adverse reactions (e.g. Stevens-Johnson syndrome, toxic epidermal necrolysis, acute generalised exanthematous pustulosis, drug rash with eosinophilia and systemic symptoms); Clostridioides difficile-associated diarrhoea (CDAD), pseudomembranous colitis.
Perform culture and susceptibility tests; consult local institutional recommendations before treatment initiation due to antibiotic resistance risks. Monitor renal, hepatic, and haematologic functions periodically (prolonged therapy); signs of anaphylaxis during 1st dose.
Overdosage
Symptoms: Nausea, vomiting, epigastric distress, diarrhoea, haematuria. Management: General supportive treatment. Close clinical and laboratory monitoring of haematological, renal, and hepatic functions and coagulation status is recommended until the patient is stable.
Drug Interactions
Reduced excretion with probenecid. Increased risk of nephrotoxicity with amphotericin B, loop diuretics, aminoglycosides, or vancomycin. Concomitant use with oral anticoagulants may prolong prothrombin time. May reduce the effects of estrogen-containing oral contraceptives. May increase metformin plasma concentrations.
Lab Interference
May result in positive direct Coombs' tests. May cause a false-positive reaction when testing for the presence of glucose in the urine using Benedict's or Fehling's solutions or with copper sulfate test tablets; false-positive serum or urine creatinine with Jaffe reaction; false-positive urinary proteins and steroids.
Action
Description: Mechanism of Action: 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 in bacterial lysis.
Synonym: cephalexin. Pharmacokinetics: Absorption: Rapidly and almost completely absorbed from the gastrointestinal tract. Time to peak plasma concentration: Approx 1 hour. Distribution: Widely distributed into body tissues, including bone, joints, and the pericardial and pleural cavities. Crosses the placenta; enters breast milk (small amounts). Plasma protein binding: Approx 10-15%. Metabolism: Not metabolised. Excretion: Via urine (>90% as unchanged drug). Elimination half-life: Approx 60 minutes.
Chemical Structure
Cefalexin Source: National Center for Biotechnology Information. PubChem Compound Summary for CID 27447, Cephalexin. https://pubchem.ncbi.nlm.nih.gov/compound/Cephalexin. Accessed Oct. 28, 2022.
Storage
Store between 20-25°C. Protect from light. Reconstituted oral susp: Store between 2-8°C.
J01DB01 - cefalexin ; Belongs to the class of first-generation cephalosporins. Used in the systemic treatment of infections.
References
Anon. Cefalexin [Cephalexin]. Lexicomp Online. Hudson, Ohio. Wolters Kluwer Clinical Drug Information, Inc. https://online.lexi.com. Accessed 01/09/2022.Anon. Cephalexin. AHFS Clinical Drug Information [online]. Bethesda, MD. American Society of Health-System Pharmacists, Inc. https://www.ahfscdi.com. Accessed 30/08/2022.BNM Group. Cephalexin ABM 250 mg and 500 mg Capsules data sheet 04 March 2019. Medsafe. http://www.medsafe.govt.nz. Accessed 30/08/2022.Buckingham R (ed). Cefalexin. Martindale: The Complete Drug Reference [online]. London. Pharmaceutical Press. https://www.medicinescomplete.com. Accessed 30/08/2022.Cefalexin 250 mg Capsules, Hard (Kent Pharmaceuticals Limited). MHRA. https://products.mhra.gov.uk. Accessed 30/08/2022.Cefalexin 250 mg/5 mL Powder for Oral Suspension (Milpharm Limited). MHRA. https://products.mhra.gov.uk. Accessed 30/08/2022.Cephalexin Capsule (Aurobindo Pharma Limited). DailyMed. Source: U.S. National Library of Medicine. https://dailymed.nlm.nih.gov/dailymed. Accessed 30/08/2022.Cephalexin for Suspension (Ascend Laboratories, LLC). DailyMed. Source: U.S. National Library of Medicine. https://dailymed.nlm.nih.gov/dailymed. Accessed 30/08/2022.Joint Formulary Committee. Cefalexin. British National Formulary [online]. London. BMJ Group and Pharmaceutical Press. https://www.medicinescomplete.com. Accessed 30/09/2022.Max Health Ltd. Cefalexin 125 mg/5 mL and 250 mg/5 mL Granules for Oral Suspension data sheet 19 November 2021. Medsafe. http://www.medsafe.govt.nz. Accessed 30/08/2022.Pharmaniaga Cephalexin Capsule 250 mg, 500 mg (Pharmaniaga Manufacturing Berhad). National Pharmaceutical Regulatory Agency - Ministry of Health Malaysia. https://www.npra.gov.my. Accessed 30/08/2022.Sofilex Powder for Oral Suspension 125 mg/5 mL (Xepa-Soul Pattinson [Malaysia] Sdn Bhd). National Pharmaceutical Regulatory Agency - Ministry of Health Malaysia. https://www.npra.gov.my. Accessed 30/08/2022.Uphalexin Capsule 500 mg, 250 mg (Kotra Pharma [M] Sdn Bhd). MIMS Malaysia. http://www.mims.com/malaysia. Accessed 30/09/2022.Uphalexin Granules 125 mg/5 mL (Kotra Pharma [M] Sdn Bhd). MIMS Malaysia. http://www.mims.com/malaysia. Accessed 30/09/2022.
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