Penicillin II Flashcards
Why has amoxicillin largely replaced ampicillin for treatment?
ampicillin had a high incidence of causing bad diarrhea as a side effect; amoxicillin lessened that side effect
Why does amoxicillin not cause diarrhea as badly as ampicillin does?
it is more completely absorbed from the GI tract
What was the first penicillin that had activity against pseudomonas, and what were its problems?
carbenicillin; even though it worked, needed very high doses for it to be effective (about 30 g per day), resistance to it developed rapidly, not effective against beta lactamases
Which of the anti-pseudomonal penicillins only has a spectrum of activity towards pseudomonas?
azlocillin
What are five anti-pseudomonal penicillins?
carbenicillin, ticarcillin, azlocillin, mezlocillin, piperacillin
Of the anti-pseudomonal penicillins, which two are mostly of historical interest now (not really used)?
carbenicillin, ticarcillin
What was the idea behind creating combination products with a penicillin and a beta-lactamase inhibitor?
the beta lactamase inhibitors (which were also beta lactams with little antibiotic activity on their own) would protect penicillins that would normally be broken down by beta lactamases so they could be effective
Ticarcillin and Clavulanic Acid is what combination product?
timentin
Ampicillin and Sulbactam is what combination product?
unasyn
Piperacillin and Tazobactam is what combination product?
zosyn
Amoxicillin and Clavulanic Acid is what combination product?
Augmentin
What are the three categories of Broad-Spectrum Penicillins?
aminopenicillins, anti-pseudomonal penicillins, penicillin/beta lactamase inhibitors
What leads to the broad spectrum penicillins’ increased activity against gram-negative bacteria? Why are they still not very useful against many gram-negative organisms?
increasing ability to penetrate the gram-negative cell wall; still not very useful against gram-negative organisms because often hydrolyzed by gram-negative beta lactamases
Which two categories of Broad-Spectrum penicillins are broken down by beta lactamases?
aminopenicillins, anti-pseudomonal penicillins
Why is ampicillin/amoxicillin not good against MSSA?
they would be broken down by the beta lactamases
Which organisms do aminopenicillins have good activity against?
streptococci, enterococci
Which organisms do aminopenicillins have moderate activity against?
enteric gram-negative rods (GNRs), Haemophilus (non-penicillinase producing organisms)
Which organisms do aminopenicillins have poor activity against?
MSSA/MRSA, anaerobes, pseudomonas, nosocomial Enterobacteriaceae (many produce beta lactamases)
What is the oral bioavailability of ampicillin?
40%
What conditions are aminopenicillins commonly used to treat?
otitis media, bacterial sinusitis, bacterial exacerbations of chronic bronchitis, some Salmonella infections
Amoxicillin has a higher incidence of what reaction compared to other penicillins?
skin rashes
Which oral form of carbenicillin is still used today only in the treatment of UTIs, and why is it good for that?
carbenicillin indanyl, cleared through the kidneys so can achieve very high concentrations in the urine (to treat UTIs)
Which type of people are usually found to have stenotrophomonas infections?
hospitalized patients who have recently gone through multiple rounds of antibiotics
What are two organisms ticarcillin is NOT active against?
Enterococci, Klebsiella
What organisms is ticarcillin good against?
anaerobes (including Bacteroides fragilis)
Ticarcillin is a ________ salt, meaning there are _____ mEq/gm of sodium per gram of drug.
di-sodium, 5.2
What is one serious disease that ticarcillin can cause?
acquired platelet dysfunction
What is the most popular anti-pseudomonal penicillin used today?
piperacillin
What organisms does piperacillin have activity against (provided they don’t produce beta lactamases)?
klebsiella, pseudomonas (most active anti-pseudomonal), serratia, enterobacter, enterococci, anaerobes (including bacteroides fragilis)
Which organisms does Zosyn (piperacillin + tazobactam) have good activity against?
gram positive aerobes: MSSA, streptococcus, gram negative aerobes: enterococci, enteric GNRs, pseudomonas, gram positive and gram negative anaerobes (especially B. fragilis)
Which organisms does Zosyn (piperacillin + tazobactam) have moderate activity against?
GNRs producing “advanced” beta lactamases
Which organisms does Zosyn (piperacillin + tazobactam) have poor activity against?
MRSA, extended-spectrum beta lactamases produces by GNRs (gram-negative rods)
Zosyn is commonly used for ______ treatment in hospitals.
empiric
Patients with __________ are at an increased risk for skin rashes when taking ampicillin/amoxicillin.
mononucleosis
Taking allopurinol with penicillins increases the incidence of _____
rash
Take probenicid with amoxicillin ________ amoxicillin levels
increases
Take warfarin with penicillins ________ the anticoagulant effect of warfarin.
increases
Taking methotrexate with penicillins _____ the exposure (effect) to methotrexate
increases
Should you warn your patient about beta lactams possibly decreasing the effectiveness of oral contraceptives?
yes, to be safe
What is neutropenia, and when does it usually occur?
abnormally low white blood cell count; usually occurs when taking high doses of penicillins over long time period
What are three penicillins which commonly cause thrombocytopenia (low platelet count)?
ticarcillin, piperacillin, mezlocillin
Hypokalemia (low potassium) can occur if the drug makes the _______ more efficient at excreting potassium.
kidney
Which penicillin commonly causes hepatitis/cholestasis (backup of bile)?
oxacillin
Which adverse penicillin reaction is rare but occurs 100% of the time in people with syphillis?
Jarixch-Herxheimer reaction
