Beta-lactamase Inhibitors Pharmacology Notes and MCQ for GPAT, NEET PG, NORCET Exams

Beta-lactamase Inhibitors Pharmacology Notes and MCQ for GPAT, NEET PG, NORCET Exams

Beta-lactamase Inhibitors

Pharmacology

  • Definition: Beta-lactamase inhibitors are drugs that inhibit the action of beta-lactamase enzymes produced by bacteria.

  • Mechanism of Action: They bind irreversibly to beta-lactamase enzymes, preventing these enzymes from breaking down beta-lactam antibiotics (e.g., penicillins).

  • Classification of Beta-lactamase Inhibitors:

    • Clavulanic acid

    • Sulbactam

    • Tazobactam

    • Avibactam (newer, non-beta-lactam structure)

  • Combination Use: Always combined with beta-lactam antibiotics (e.g., Amoxicillin + Clavulanic acid).

Uses

  • Treat infections caused by beta-lactamase-producing bacteria.

  • Common in:

    • Respiratory tract infections

    • Urinary tract infections (UTIs)

    • Intra-abdominal infections

    • Skin and soft tissue infections

    • Hospital-acquired infections (e.g., piperacillin/tazobactam)

Side Effects

  • Common:

    • Diarrhea

    • Nausea

    • Rash

  • Less Common:

    • Hypersensitivity reactions

    • Hepatotoxicity (especially with clavulanic acid)

    • Pseudomembranous colitis (due to C. difficile)

Drug Interactions

  • Allopurinol: Increased risk of rash when used with amoxicillin-clavulanate.

  • Oral contraceptives: May reduce efficacy—advise backup contraception.

  • Anticoagulants (e.g., warfarin): May enhance the effect, increasing bleeding risk.

  • Methotrexate: Beta-lactam antibiotics may reduce methotrexate clearance.

Comparative Pharmacology of Beta-lactamase Inhibitors

Feature Clavulanic Acid Sulbactam Tazobactam Avibactam
Structure Beta-lactam Beta-lactam Beta-lactam Non-beta-lactam diazabicyclooctane
Mechanism of Action Irreversibly inhibits beta-lactamases Irreversibly inhibits beta-lactamases Irreversibly inhibits beta-lactamases Reversible covalent inhibition of beta-lactamases
Spectrum of Inhibition Mainly Class A β-lactamases (e.g. TEM) Class A and some Class C Class A and some Class C Class A, C, and some D β-lactamases
Intrinsic Antibacterial Activity Minimal Moderate (especially vs Acinetobacter) Minimal None
Common Combinations Amoxicillin + Clavulanic acid Ampicillin + Sulbactam Piperacillin + Tazobactam Ceftazidime + Avibactam
Oral Bioavailability Good (used orally) Poor (IV use only) Poor (IV use only) IV use only
Metabolism Hepatic Hepatic and renal Hepatic and renal Minimal metabolism
Excretion Renal Renal Renal Renal
Activity Against ESBL Limited Limited Limited Effective
Activity Against KPC & AmpC No No No Yes
Clinical Use Outpatient RTIs, UTIs Hospital-acquired infections Broad-spectrum nosocomial infections MDR Gram-negative infections

MCQs (Multiple Choice Questions)

  1. Which of the following is a beta-lactamase inhibitor?
    A. Ceftriaxone
    B. Amoxicillin
    C. Tazobactam
    D. Gentamicin
    Answer: C. Tazobactam

  2. Beta-lactamase inhibitors are typically used to:
    A. Increase kidney excretion of antibiotics
    B. Decrease gastric irritation
    C. Protect beta-lactam antibiotics from degradation
    D. Reduce antibiotic resistance in fungi
    Answer: C. Protect beta-lactam antibiotics from degradation

  3. Which combination is correct for treatment of resistant bacterial infections?
    A. Amoxicillin + Erythromycin
    B. Piperacillin + Tazobactam
    C. Cephalexin + Sulbactam
    D. Vancomycin + Clavulanic acid
    Answer: B. Piperacillin + Tazobactam

  4. A common side effect of amoxicillin-clavulanic acid is:
    A. Constipation
    B. Hepatotoxicity
    C. Bradycardia
    D. Hyperkalemia
    Answer: B. Hepatotoxicity

  5. Which of the following drugs may interact with beta-lactamase inhibitor combinations?
    A. Digoxin
    B. Allopurinol
    C. Acetaminophen
    D. Furosemide
    Answer: B. Allopurinol

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