Miscellaneous Antibiotics Flashcards
Fluoroquinolones
ciprofolxacin* levofloxacin* moxifloxacin* gemifloxacin norfloxacin oflaxacin
Distribution of Fluoroquinolones
- good tissue and fluids distribution except CNS
- all undergo renal elimination except moxifloxacin
- Half lives range from 4-12 hours (allows for 1/day dosing)
MOA of fluoroquinolones
bactericidal
- inhibit DNA gyrase and topoisomerase necessary for replication of bacteria
Spectrum of fluoroquinolones
Aerobic gram neg: all fluoroquinolones
Pseudomonas Aeroginosa: cipro or levofloxacin
Gram + (including Strep pneumonia): levofloxacin, moxifloxacin, and gemfloxacin
Anaerobic: moxifloxacin
Clinical uses of fluorquinolones
Urinary tract= DOC -> cipro
- pneumonia
- STIs
- skin and soft tissue (not first line)
- GI infections
- Traveler’s diarrhea
- osteomyelitis (good penetration into bone)
What FQ’s are active against gram + respiratory infections (Strep)?
Levofloxacin, moxifloxacin, and gemifloxacin
Black box warning of fluorquinolones?
associated with an increased risk of tendinitis and tendon ruptures in all ages, risk is increased in older patients usually over 60 you, in patients taking corticosteroids, and pts with kidney, hearth or lung transplants
SE’s of FQ’s
N/D, dizziness, confusion, tendon rupture, QT prolongation (ventricular tachycardia= death)
tendonitis -> RF for rupture, peripheral neuropathy (on long term therapy)
Drug interactions of FQ’s
- ciprofloxacin potent inhibitor of CYP4501A2 -> theophylline, warfarin, tizanidine, propranolol
- antacids, sucrlafate, magnesium, calcium, iron all decrease the absorption of FQs
- corticosteroids increase risk of tendon ruptures
When would you not have to adjust dose for renal failure pts on FQs?
if they are on moxifloxacin
Do FQ’s cover pseudomonas?
Yes, contains the only oral agents against pseudomonas
CI of FQs
not for use in pregnancy or children -> in pregnancy and lactation= exposure to infant (crosses placental barrier)
in peds= arthropathy and osteochondrosis
- caution when using in hepatic dysfunction
Sulfonamides
sulfamethoxazole/Trimethoprim (SMX-TMP) (Bactrim DS, Septra)
Distribution of Sulfonamides
oral med with good distribution to all body tissues and fluids -> CSF, pleural fluid, synovial fluid
-eliminated through liver and kidneys
MOA of sulfonamides
Folic acid synthesis inhibitors:
Bacteria need to produce folic acid to survive -> SMX inhibits dihydropteroate syntheses and TMP inhibits dihydrofolate reductase
Clinical uses of sulfonamides?
UTIs PCP (pneumonia seen in immunocompromised pts) toxoplasmosis Gram + and - infections MRSA (have resistance to strep pneumo)
SE’s of sulfonamides?
**Rash (very obvious it is sulfa related), fever, N/V/D, SJS (shed skin), vasculitis, hemolytic anemia if underlying G6PD deficiency, thrombocytopenia
Stevens-Johnson syndrome?
cell death causes the dermis and epidermis to separate
-hypersensitivity reaction of skin and mucous membranes
Drug interactions of sulfonamides
up to 70% protein bound -> displaced other drugs
potentiates the effects of:
warfarin, phenytoin, hypoglycemic agents, methotrexate(folic acid inhibitor -> together could cause folic def)
B blockers: increase activity -> severe bradycardia
Metabolism of sulfonamides
metabolized in liver
excreted renally
-reduce dose by 50% if CrCl 15-30 not recommended if CrCl
Why are sulfonamides CI at end term of pregnancy?
due to development of kernicterus in infants (bilirubin induced brain dysfunction b/c of hemolytic anemia leads to increased bilirubin)
Sulfonamides allergy?
don’t use with a sulfa allergy
Nitrofurantoin (Macrobid)
only for treatment and prevention of uncomplicated UTIs
PO
Metabolism of Macrobid
rabidly absorbed and only in serum for 30 minutes
- cleared renally and concentrated in urine
- inadequate drug levels in bladder if CrCl abnormal (GFR
MOA of macrobid
thought to disrupt bacterial cell wall synthesis through inhibition of bacterial enzymes
Macro bids are effective against what organisms?
E. coli Citrobacter Staph saprophyticus enterococus faecalis enterococcus faecium
-some emerging resistance against enterobacter and Klebsiella
SE’s of Macrobid
Most common: N/V
pulmonary reactions: pulmonary infiltrates, pneumonitis, pulmonary fibrosis
Hepatic effects (rare): hepatitis, hepatic necrosis
peripheral neuropathy in long term use in patients with renal failure
Pulmonary reactions in macrobid use?
- acute pulmonary reactions usually manifested by sudden, severe dyspnea, chills, chest pain, fever, and cough
- pulmonary infiltration with consolidation or pleural effusion on radiographs and eosinophilia also may occur
- usually evident within first week of tx and reversible when drug d/c
- Resolution is often dramatic
Drug interactions of Macrobids
No significant drug interactions because it isn’t in plasma for more than 30 minutes -> urinary tract
Safety of macrobids
pregnancy: category B
But CI at term due to possibility of causing hemolytic anemia in newborn
-dont use in lactation
-safety and efficacy not established in children
Who should avoid using macrobids?
avoid use in older adults, avoid using for long term suppression of infection
Anti-anerobic med?
Metronidazole (flagyl)
Metabolism of flagyl?
metabolized by the liver
- adjust dose with hx of liver failure
- absorbed well PO
- good tissue penetration in most locations
- Half life 6-9 hours
MOA of flagyl
inhibitor of bacterial protein synthesis -> causes DNA strand breakage therefore inhibiting bacterial protein synthesis
Spectrum of Flagyl
good against gram + and - anaerobes
Helicobacter pylori
Trichomonas vaginalis (STI in men and women)
flagyl is DOC for?
Anerobic infections
bacterial vaginosis
trichomoniasis
C. diff diarrhea
formulations of flagyl?
oral, IV, topical (roseacea), intravaginal
Black box warning for flagyl
metronidazole has been shown to be carcinogenic in mice and rats. Unnecessary use of drug should be avoided.
SE’s of flagyl?
most common: N/V, abdominal pain and metallic taste
- seizures (high doses),
- peripheral neuropathy (prolonged courses)
- pancreatitis
Drug interactions of flagyl?
enhances anticoag effects of warfarin
-alcohol: flushing, palpitations, nausea, vomiting
- inhibitor of CYP34A so potential for many drug interactions
- phenobarbital, phenytoin, rifampin: all increase metabolism of metronidazole which decreases the serum concentration and may lead to tx failure
