Beta-lactamase Inhibitors Pharmacology Notes and MCQ for GPAT, NEET PG, NORCET Exams
Beta-lactamase Inhibitors
Pharmacology
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Definition: Beta-lactamase inhibitors are drugs that inhibit the action of beta-lactamase enzymes produced by bacteria.
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Mechanism of Action: They bind irreversibly to beta-lactamase enzymes, preventing these enzymes from breaking down beta-lactam antibiotics (e.g., penicillins).
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Classification of Beta-lactamase Inhibitors:
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Clavulanic acid
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Sulbactam
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Tazobactam
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Avibactam (newer, non-beta-lactam structure)
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Combination Use: Always combined with beta-lactam antibiotics (e.g., Amoxicillin + Clavulanic acid).
Uses
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Treat infections caused by beta-lactamase-producing bacteria.
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Common in:
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Respiratory tract infections
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Urinary tract infections (UTIs)
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Intra-abdominal infections
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Skin and soft tissue infections
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Hospital-acquired infections (e.g., piperacillin/tazobactam)
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Side Effects
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Common:
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Diarrhea
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Nausea
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Rash
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Less Common:
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Hypersensitivity reactions
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Hepatotoxicity (especially with clavulanic acid)
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Pseudomembranous colitis (due to C. difficile)
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Drug Interactions
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Allopurinol: Increased risk of rash when used with amoxicillin-clavulanate.
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Oral contraceptives: May reduce efficacy—advise backup contraception.
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Anticoagulants (e.g., warfarin): May enhance the effect, increasing bleeding risk.
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Methotrexate: Beta-lactam antibiotics may reduce methotrexate clearance.
Comparative Pharmacology of Beta-lactamase Inhibitors
Feature | Clavulanic Acid | Sulbactam | Tazobactam | Avibactam |
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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)
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Which of the following is a beta-lactamase inhibitor?
A. Ceftriaxone
B. Amoxicillin
C. Tazobactam
D. Gentamicin
Answer: C. Tazobactam -
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 -
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 -
A common side effect of amoxicillin-clavulanic acid is:
A. Constipation
B. Hepatotoxicity
C. Bradycardia
D. Hyperkalemia
Answer: B. Hepatotoxicity -
Which of the following drugs may interact with beta-lactamase inhibitor combinations?
A. Digoxin
B. Allopurinol
C. Acetaminophen
D. Furosemide
Answer: B. Allopurinol