Macrolides, Fluroquinolones, Aminoglycosides Flashcards
Macrolides include which antibiotics?
Erythromycin Azithromycin Clarithromycin Telithroycin (ketolide) Fidaxomicin
The MOA of Macrolides:
Inhibition of protein synthesis via the 50S ribosomal subunit
Bacteriostatic
Which two drugs should you not use macrolides with and why?
Clindamycin and chloramphenicol
Overlaps with binding site creating competition and no benefit
What types of organisms are macrolides effective agains?
Gram + and intracellular bac
Atypical org: Chlamydia, Mycoplasma, Legionella
CAP, acute bac sinusitis, acute exacerbation of chronic bronchitis
MAC (azithro, clarithro)
H.pylori (clarithro)
Which macrolide has the longest half-life and what does this mean about treatment?
Azithromycin
Can give a 3-5day course and intracellular levels can continues for days (Z-pak)
What is different about the macrolide fidaxomicin (Dificid) and how is it used?
Bacteriocidal against Gram + anaerobes/aerobes
Used in the treatment of C.diff (minimal systemic absorption, excreted in the feces)
AE of macrolides include:
GI distress
Hepatotoxicity, esp telithromycin (ex-don’t use to treat sinusitis)
Dose-dependent ototoxicity (prolonged, high doses)
DI of erythromycin, clarithromycin, telithromycin:
Inhibition of CYP3A4
Telithromycin is also a substrate of CYP3A4
Which macrolide produces the least amount of DI and can be considered your ‘safest’?
Azithromycin
Quinolones include which drugs?
Norfloxacin Ciprofloxacin Ofloxcin (topical) Levofloxacin Sparfloxacin Lomefloxacin Moxifloxacin Trovafloxacin
What is the MOA of quinolones?
Inhibit DNA gyrase
Bacteriocidal
How may resistance to quinolones occur?
Mutation change in DNA gyrase
Quinolones cover which organisms and how is this related to the treatment of CAP?
Gram +, -, and atypicals, M. Tb
(poor anaerobic coverage)
To cover a patient for CAP you can prescribe ceftriaxone and azithromycin (Gram+ and atypical coverage) or prescribe quinolone alone which has broader spectrum coverage and drop to just one more narrow spectrum once pneumonia isolated
What is true of the IV and oral forms of quinolones?
They share bioequivalence
What patient populations are quinolones CI in?
Children, pregnancy, breastfeeding
Quinolones can cause what serious AE?
Erosion of cartilage that can lead to tendinitis and tendon rupture
Other AE of Quinolones include:
QTc prolongation Photosensitivity/phototoxicity Hepatic damage (trovafloxacin)
How are quinolones cleared from the body?
Renally
DI with quinolones include:
Antacids and other products containing cations significantly decrease absorption (bind and prevent absorption)
Which quinolone is good for the treatment of Pseudomonas, UTIs, and intra-abdominal infections?
Ciprofloxacin
Which quinolone is broad spectrum and good for the treatment of Pseudomonas, UTIs, URIs, and is the L isomer of ofloxacin?
Levofloxacin
Which quinolone is used for BMT prophylaxis?
Norfloxacin
Aminoglycosides include:
Amikacin Gentamicin Tobramycin (IV, IM) Neomycin (oral, topical, Streptomycin (IM)
How is streptomycin’s MOA different from other aminoglycosides?
MOA: Inhibits initiation of bacterial protein synthesis
Only 1st line AG for TB
What is the MOA for most aminoglycosides?
Irreversible binding to the 30S ribosomal unit
Produces misreading of bacterial mRNA resulting in faulty bacterial protein synthesis
Aminoglycosides are bacteriocidal and demonstrate _____ dependent killing.
concentration
Peak levels are important = need high enough concentrations for drug to be bacteriocidal
What type of organisms do aminoglycosides cover?
Gram - , including Pseudomonas
Which drug class do aminoglycosides have synergy with?
Beta-lactams
often for treatment with Gram + endocarditis
What is the post antibiotic effect associated with aminoglycosides?
The drug levels in plasma have subsided yet the antibiotic continues to have effect d/t the irreversible binding to the 30S subunit. Trough monitoring to monitor for toxicity and prevent accumulation of drug
Are aminoglycosides hydrophilic or lipophilic and how does that affect them?
Hydrophilic
Poor oral absorption
Not significantly metabolized (renally excreted)
Lack CNS penetration
AE of aminoglycosides include:
Ototoxicity (highest risk from streptomycin)
Nephrotoxicity (others more than streptomycin)
Neuromuscular blockade with high doses
What should be monitored in a patient taking aminoglycosides?
Serum Cr
Peak and trough levels if pt: unstable renal func, unstable volume status, poor clinical response, change in aminoglycoside dose
When are peak levels not necessary for an aminoglycoside?
When using gentamicin for Gram + synergy
In treatment with aminoglycosides peaks are drawn for _______ and troughs are drawn for ______.
Efficacy
Toxicity
Aminoglycoside peak and trough parameters:
Peak: 10-20mg/L (3-5mg/L for synergy)
Trough: <1mg/L
What is often prescribed for traveller’s diarrhea?
Cipro
