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Cephalexin is a widely used antibiotic in the treatment of bacterial infections. It belongs to the class of drugs known as cephalosporins, which are related to penicillins. This guide provides an overview of cephalexin’s classifications and mechanisms to assist pharmacy technicians in understanding its role in antimicrobial therapy.
Classification of Cephalexin
Cephalexin is classified as a first-generation cephalosporin antibiotic. It is primarily used to treat infections caused by gram-positive bacteria and some gram-negative bacteria. Its classification influences its spectrum of activity, dosing, and administration considerations.
Cephalosporin Generations
- First-generation: Cephalexin, Cefazolin
- Second-generation: Cefuroxime, Cefoxitin
- Third-generation: Ceftriaxone, Ceftazidime
- Fourth-generation: Cefepime
- Fifth-generation: Ceftaroline
Mechanism of Action
Cephalexin works by inhibiting bacterial cell wall synthesis. It binds to penicillin-binding proteins (PBPs) located inside the bacterial cell wall. This binding prevents the cross-linking of peptidoglycan chains, which are essential for cell wall strength and rigidity.
The disruption of cell wall synthesis leads to bacterial cell lysis and death, especially in actively dividing bacteria. Cephalexin’s mechanism makes it effective against susceptible bacteria but not against bacteria that produce beta-lactamase enzymes.
Pharmacokinetics and Spectrum
Cephalexin is well-absorbed orally, with peak plasma concentrations occurring within an hour. It is primarily excreted unchanged via the kidneys. Its spectrum includes gram-positive organisms such as Streptococcus pneumoniae and Staphylococcus aureus, but it has limited activity against gram-negative bacteria.
Clinical Uses
Cephalexin is commonly prescribed for skin and soft tissue infections, respiratory tract infections, otitis media, and urinary tract infections. Its efficacy depends on the susceptibility of the causative bacteria.
Important Considerations for Pharmacy Techs
- Ensure proper storage, as cephalexin is sensitive to moisture.
- Check for patient allergies to penicillins or other cephalosporins.
- Be aware of potential drug interactions, such as with aminoglycosides or anticoagulants.
- Educate patients on completing the full course of therapy to prevent resistance.