Medications Flashcards
How does a bacteria become resistant to penicillin?
Resistance is often due to beta-lactamase, a bacterial enzyme that hydrolyzes and inactivates the beta-lactam ring. The coadministration of a beta-lactamase inhibitor such as tazobactam prevents beta-lactamase producing organisms from inactivating penicillins, which extends their spectrum of activity (broadens the range of microbes that can be treated).
Penicillin is used for:
Gram + cocci, N meningitidis, and T pallidum
Beta lactamase inhibitors MOA: Examples
Added with use of penicillins to protect destruction from beta lactamases
Clavulanic Acid, Avibactam, Sulbactam, Tazobactam - end in bactam.
Aminoglycosides MOA, clinical use:
GNAT: Gentamicin, Neomycin, Amikacin, Tobramycin, Streptomycin
Aminoglycosides inhibit bacterial protein synthesis and genetic code reading by blocking the 30S ribosomal subunit.
Penicillins are often coadministered with aminoglycosides to aid in their entry into the cell (penicillins disrupt the cell wall, which allow aminoglycosides to penetrate the bacteria).
Associated with nephrotoxicity and ototoxicity (hearing loss)
Use: severe gram NEGATIVE ONLY rod infections (Streptomycin)
Buy at 30, ccel at 50
Aminoglycosides, Tetracylines: 30S inhibitor
Chloramphenicol, clindamycin, Erythromycin, Linezolid: 50S inhibitors
Tetracycline MOA:
Do NOT take with what?
Contraindicated for what?
Use for what?
Bind to 30S and prevent attachment of aminoacyl-tRNA.
Do NOT take with milk, antacids, or iron containing preparations bc divalents inhibit drugs absorption in the gut
DON’T TAKE WHEN PREGGERS, or else baby will have bone probs.
Use for: Mycoplasma, Rickettsia, Chlamydia, MRSA
Macrolides MOA
-THROMYCIN
inhibit protein synthesis by blocking translocation; binds to 23S of 50S subunit
Treat for: atypical penumonias (myco, chalmyd, legion), chalmydia, gram + cocci, B pertussus, strep infections in patients allergic to penicilin
GRAM POSITIVE ONLY
Fluoroquinolone:
fluoroquinolone (DNA gyrase inhibitor)
FLOXACIN
-inhibit prokaryotes topoisomerase II (DNA gyrase)
Use for: gram negative rods of GU and GI tracts (psudomonas)
Contraindicated in: PREGNANCY, CHILDREN bc damage to cartilage, prolong QT interval . can cause arthitis in patients over 60 taking prednisone
TMP-SMX affects what?
Trimethoprim-sulfamethoxazole affects folic acid synthesis.
Jarisch-Herxheimer reaction happens when?
The Jarisch-Herxheimer reaction is an acute inflammatory reaction that occurs within hours of treatment for spirochetal infections (eg, syphilis). The rapid lysis of spirochetes releases inflammatory bacterial lipoproteins into the circulation and causes acute fever, rigors, and myalgias.
Rifampin four Rs
Inhibits DNA dependent RNA polymerase
RNA polymerase inhibitor
Ramps up microsomal cytochrome p450
Red/orange body fluid
Rapid resistance if used alone
Rifampin ramps up cyt 450, but rifabutin does not.
Isoniazid:
inhibition of mycolic acid synthesis by bacterial peroxidase catalase, KatG
Vitamin B6 stuff
Ethambutol
Eyethambutol
inhibition of arabinosyl transferase
Side effect: optic neuropathy
Aminoglycoside mechanism of resistance:
bacterial transferase enzymes inactivate the drug by acetylation, phosphorylation, or adenlyation
Cephalosporin MOA:
inhibit cell wall synthesis
organisms that ARE NOT covered by ceph. 1-4
LAME
listeria, atypicals (chlamy, mycolasma), MRSA, Enterococci
What’s special about 3rd generation cephalosporins?
they cross the blood brain barrier- Certriaxone for meningitis, gonorrhea, disseminated lyme, ceftazidime for pseudomonas
Carbapenem MOA
binds to penicillin-binding protein and inhibits cell wall synthesis ; give with cilastatin
broad spectrum; give only when very ill
major side effect of amphotericin B
Hypokalemia and hypomagnesemia are common electrolyte disturbances in patients undergoing treatment with amphotericin B and reflect an increase in distal tubular membrane permeability.
What’s a common side effect of TMP-SMX, esp in the elderly?
Hyperkalemia is a common adverse effect of trimethoprim-sulfamethoxazole due to the trimethoprim-induced blockade of the sodium channels in the collecting duct, which prevents sodium-potassium exchange and reduces renal excretion of potassium (similar to the action of amiloride). This effect is often magnified in the elderly population, those with renal failure, or those given other potassium-sparing diuretics, ACE inhibitors, or angiotensin receptor blockers.
What med is used for ganicyclovir resistant CMV? and what’s the side effect?
Foscarnet is an analog of pyrophosphate that can chelate calcium and promote nephrotoxic renal magnesium wasting. These toxicities can result in hypocalcemia and hypomagnesemia, which can cause seizures.
-azoles MOA and adverse?
inhibit fungal ergosterol synthesis by inhibiting cyt P450 enzyme that converts lanosterol to ergosterol
-gynecomastia, liver, QT interval prolongation
Metronidazole MOA:
forms toxic free radical metabolites in the bacterial cell that damages DNA, bactericidal; antiprotozoal
