Antimicrobials for GIT 2 Infections: Antibacterials

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Questions and Answers

What is a significant pharmacokinetic consideration for fluoroquinolones like ciprofloxacin?

High protein binding effect leading to toxicity

Renal excretion requires dose adjustment in renal impairment (correct)

High absorption in the presence of dairy products

Low bioavailability compared to other antibacterials

Which adverse effect is specifically associated with fluoroquinolones such as ciprofloxacin?

Increased gastrointestinal disturbance

Infusion reaction causing dizziness

Peripheral neuropathy leading to neurotoxicity (correct)

Hypersensitivity reaction leading to a rash

Which mechanism of action is true for vancomycin?

Inhibits bacterial cell wall synthesis (correct)

Disrupts protein synthesis by binding to ribosomal RNA

Inhibits folate synthesis in bacteria

Interferes with bacterial DNA replication

What is a common contraindication for the use of fluoroquinolones?

Individuals with myasthenia gravis Signup and view all the answers

What is a potential serious adverse effect of vancomycin when used in combination with other high-risk drugs?

Nephrotoxicity and ototoxicity Signup and view all the answers

What is the ideal therapeutic use for vancomycin in gastrointestinal infections?

Targeting C. difficile Signup and view all the answers

What is a significant adverse effect associated with the use of fluoroquinolones?

Tendon damage Signup and view all the answers

How should dose adjustments be handled for patients with renal impairment taking fluoroquinolones?

Adjust the dose Signup and view all the answers

What pharmacokinetic consideration affects the absorption of fluoroquinolones?

Absorption impaired by antacids Signup and view all the answers

What complication is unique to the use of ciprofloxacin in patients with myasthenia gravis?

Worsening of muscle strength Signup and view all the answers

What is a common renal-related adverse effect of vancomycin when absorbed?

Nephrotoxicity Signup and view all the answers

What effect does ciprofloxacin have on the metabolism of theophylline?

Decreases metabolism Signup and view all the answers

What is the primary risk of combining vancomycin with aminoglycoside antibiotics?

Greater nephrotoxicity risk Signup and view all the answers

What specific action of fluoroquinolones contributes to their effectiveness against bacterial infections?

Disruption of DNA replication Signup and view all the answers

What is a common side effect of vancomycin associated with rapid infusion?

Red man syndrome Signup and view all the answers

Study Notes

Antimicrobials for GIT Infections: Antibacterials

Learning Outcomes: Identify antibacterial drugs for gastrointestinal tract infections, describe mechanisms of action for fluoroquinolones (e.g., ciprofloxacin) and glycopeptides (e.g., vancomycin), understand pharmacokinetic considerations for both, and describe adverse effects and contraindications.

Fluoroquinolones: Mechanism of Action

Fluoroquinolones inhibit type II and type IV topoisomerases, crucial enzymes in DNA replication.
They interfere with DNA gyrase, preventing the unwinding and rejoining of DNA strands during replication.
This disruption leads to DNA damage and ultimately cell death.

Fluoroquinolones: Pharmacokinetic Considerations

Fluoroquinolones have high bioavailability (80-95%).
Absorption is impaired by antacids and dairy products (e.g., Ca2+, Mg2+).
Excretion is primarily renal, through tubular and glomerular pathways.
Dosage adjustments are necessary in patients with renal impairment.

Fluoroquinolones: Adverse Effects & Contraindications

Potential adverse effects include dizziness, faintness, hypersensitivity, peripheral neuropathy, and increased seizure risk.
Avoid use in individuals with myasthenia gravis due to potential for worsened muscle weakness.
Tendon damage, including Achilles tendon rupture, is a possible adverse effect.
Interactions exist; ciprofloxacin inhibits CYP1A2, potentially increasing theophylline levels and narrowing its therapeutic window.

Glycopeptides: Mechanism of Action

Glycopeptides, like vancomycin, inhibit cell wall synthesis in bacteria.
They bind to the D-alanyl-D-alanine terminal portion of the peptide chain, blocking the formation of crosslinks crucial for cell wall integrity.
This prevents cell wall synthesis and leads to bacterial death.

Glycopeptides: Pharmacokinetic Considerations

Vancomycin has poor absorption.
Absorption can be enhanced in inflammatory GI conditions.
Renal excretion (glomerular) is the primary pathway if absorbed.
Accumulation occurs in renal impairment.

Glycopeptides: Adverse Effects & Contraindications

Vancomycin can cause gastrointestinal disturbances and hypersensitivity reactions.
Nephrotoxicity and ototoxicity (dizziness, vertigo, tinnitus) are potential adverse effects, especially when combined with other nephro- or ototoxic drugs.
Infusion reactions ("red man syndrome," histamine release) can occur.
Dose adjustments in renal impairment are crucial.

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Description

This quiz covers antibacterial drugs used for gastrointestinal tract infections, focusing on mechanisms of action for fluoroquinolones and glycopeptides. It also includes pharmacokinetic considerations, adverse effects, and contraindications associated with these medications.