Pharmacology of Hydrophilic Antibiotics (BMS161)

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Questions and Answers

What is the primary indication for using Streptomycin?

Hepatic coma

Tuberculosis (correct)

Pseudomembranous colitis

MRSA infections

Which of the following adverse effects is associated with the release of histamine?

Nephrotoxicity

Neuromuscular paralysis

Ototoxicity

Red Man Syndrome (correct)

What is the mechanism of action of Daptomycin?

Disruption of cell membrane (correct)

Inhibition of 50S subunit

Inhibition of DNA replication

Inhibition of protein synthesis

What is a common side effect of using Linezolid for more than 10 days?

Thrombocytopenia Signup and view all the answers

Why is Daptomycin not used to treat pneumonia?

It is inactivated by pulmonary surfactant Signup and view all the answers

What is the primary indication for using Vancomycin?

Gram-positive infections Signup and view all the answers

What is the mechanism of action of Streptogramins?

Inhibition of 50S subunit Signup and view all the answers

What is a common side effect of using Neomycin?

Ototoxicity Signup and view all the answers

What is the primary mechanism of action of aminoglycosides?

Protein synthesis inhibition Signup and view all the answers

Why are aminoglycosides not used against anaerobes?

They are not effective against anaerobic bacteria Signup and view all the answers

What is the primary route of administration for aminoglycosides?

Parenteral administration Signup and view all the answers

Why are aminoglycosides given as once-daily dosing?

Because they have a concentration-dependent effect with a post-antibiotic effect (PAE) Signup and view all the answers

What is the primary mechanism of elimination for aminoglycosides?

Renal elimination Signup and view all the answers

Why is vancomycin given as an intravenous infusion over 60-90 minutes?

Because it has a time-dependent effect Signup and view all the answers

What is the primary mechanism of action of vancomycin?

Cell wall inhibition Signup and view all the answers

What is the primary indication for streptomycin?

Tuberculosis Signup and view all the answers

What is a crucial factor to consider when selecting an antibiotic for a pregnant woman?

The risk of kernicterus Signup and view all the answers

Which of the following antibiotics is associated with arthropathy?

Quinolones Signup and view all the answers

What is the primary consideration when initially selecting an antibiotic for a patient?

The broadest spectrum of activity Signup and view all the answers

What is a significant concern when using aminoglycosides in neonates?

The risk of ototoxicity Signup and view all the answers

In what population is the use of quinolones currently justified?

Children with cystic fibrosis Signup and view all the answers

What is the primary goal of subsequent questions to consider once a specific cause is identified?

To narrow the spectrum of the initial empiric drug Signup and view all the answers

Study Notes

Hydrophilic Antibiotics

Aminoglycosides are used parenterally in serious gram-negative infections, but not against anaerobes.
Hydrophilic antibiotics are given orally due to poor absorption.
Adverse effects of hydrophilic antibiotics include ototoxicity, nephrotoxicity, and neuromuscular paralysis.

Aminoglycosides

Mechanism of action: Protein synthesis inhibition.
Characteristics: Concentration-dependent with PAE (Post-Antibiotic Effect).
Administration: Given as once-daily dosing intravenously.
Members: Streptomycin, Gentamicin, Amikacin, Tobramycin, and Neomycin (oral or topical only).
Pharmacokinetics: Renally eliminated, not absorbed orally, and not cross BBB (except in inflammation).
Accumulated in the renal cortex and inner ear, and cross the placental barrier.
Spectrum: Active against aerobic Gram-negative bacteria.
Uses: Gram-negative infections, peritonitis, septicemia, pneumonia, endocarditis, UTI, and TB.

Vancomycin

Mechanism of action: Cell wall inhibition.
Characteristics: Time-dependent.
Administration: Intravenous infusion over 60-90 minutes.
Spectrum: Active against anaerobic Gram-positive bacteria.
Uses: MRSA (ORSA), severe staph in B-lactam allergy, and oral in pseudomembranous colitis.
Adverse effects: Red Man Syndrome, fever, chills, and rigors.

Alternative Antibiotics in Vancomycin Resistant Strains

Daptomycin: Cell membrane inhibition, administered IV/IM, and has side effects like myopathy and elevated liver enzymes.
Streptogramins: 50 S subunit inhibition, administered orally/IV, and has side effects like arthralgia, myalgia, and thrombocytopenia.
Linezolid: 50 S subunit inhibition, administered IV, and has side effects like GIT disturbance, thrombocytopenia, and MAOI property.

General Principles of Anti-microbial Therapy

Indication of antimicrobial agent based on clinical findings.
Obtain appropriate clinical specimens for microbiologic diagnosis.
Identify likely etiologic agents for the patient's illness.
Consider patient factors (age, gender, pregnancy, lactation, neonates, children) for antibiotic selection.
Consider rational antibiotic prescription, including the dose, route, and duration of therapy.
Consider drug interaction with antibiotics.

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Description

This quiz covers the lecture on chemotherapy pharmacology, focusing on hydrophilic antibiotics and their pharmacokinetics, particularly aminoglycosides.