WIKI PHARMA-MNU - 1st generation cephalosporines

Introduction
Illustrated mechanism of action
Examples of Medication Brand Names (with Images)
Indication
Side Effects
Precautions & Contraindications
Monographs
Reference

Introduction

First-generation cephalosporins are a class of beta-lactam antibiotics that were among the earliest cephalosporins developed. They were introduced in the 1960s and are structurally and functionally related to penicillins. These antibiotics are primarily effective against Gram-positive bacteria, with limited activity against Gram-negative organisms.

Mechanism of action

First-generation cephalosporins (like cefazolin, cephalexin, cefadroxil, cefradine, and cefalotin) are β-lactam antibiotics. Their mechanism of action is to inhibit bacterial cell wall synthesis by binding to penicillin-binding proteins (PBPs), which are essential for the cross-linking of peptidoglycan layers in the bacterial cell wall. This disruption leads to a weakened cell wall structure, causing osmotic instability and cell lysis, resulting in bacterial cell death.

Examples of Medication Brand Names

Oral AB

Parenteral AB

Indication

1. Skin and Soft Tissue Infections caused by Staphylococcus aureus and Streptococcus pyogenes

2. Surgical Prophylaxis especially in clean surgeries (e.g., orthopedic, cardiac) cefazolin is commonly used

3. Urinary Tract Infections caused by susceptible E. coli, Klebsiella, or Proteus.

4. Respiratory Tract Infections (Mild) such as pharyngitis or tonsillitis due to Streptococcus pyogenes

Side Effects

Common Side Effects of Cephalosporins:

• Gastrointestinal disturbances (e.g., nausea, vomiting, diarrhea)

• Allergic reactions (e.g., rash, itching, mild swelling)

• Secondary fungal infections (e.g., oral or vaginal candidiasis)

Less Common but Important Side Effects:

• Severe allergic reactions (e.g., urticaria, anaphylaxis – rare but serious)

• Abdominal pain or liver enzyme elevation

• Hematologic effects (e.g., leukopenia, thrombocytopenia – rare)

• Renal impairment (especially with prolonged use or in elderly patients)

Precautions & Contraindications

the main precautions to consider when using first-generation cephalosporins (e.g., cephalexin, cefazolin):

1. Allergy Risk

Cross-reactivity with penicillin: Patients with a history of penicillin allergy, especially anaphylaxis or severe reactions, may also react to cephalosporins.

2. Renal Impairment

Cephalosporins are excreted by the kidneys.

Dose adjustment is needed in patients with renal dysfunction to avoid toxicity.

3. Gastrointestinal Issues

May cause diarrhea, nausea, vomiting, and in rare cases, Clostridioides difficile-associated diarrhea (CDAD).

4. Drug Interactions

May interact with probenecid (increases serum levels).

May enhance the effects of oral anticoagulants (e.g., warfarin).

5. Seizure Risk

High doses or accumulation in renal impairment can rarely cause neurotoxicity or seizures, especially in those with CNS disorder

Monographs