Miscellaneous Antibiotics Flashcards
What are the most commonly prescribed fluoroquinolones?
cipro, levofloxacin (Levaqin), moxifloxacin (avelox)
Describe how fluoroquinolones work
Good tissue distribution and distribution into fluids except CNS. All undergo renal elimination except moxifloxacin. Half lives from 4-12 hours. Inhibit DNA gyrase and topoisomerase IV necessary for replication of bacteria
What are the spectrums of activity for fluorquinolones?
aerobic gram (-): all fluoroquinolones. pseudomonas: cipro, levo. gram (+): levo, moxi, gem. anaerobic: moxi
What kind of diseases can be treated with fluoroquinolones?
UTI, pneumonia, STIs, skin and soft tissue, GI, traveler’s diarrhea, osteomyelitis
How should fluoroquinolones be used to treat HAP?
Use ciprofloxacin or levofloxacin in addition to other agents for their Pseudomonas coverage
What is the black box warning associated with fluoroquinolones?
increased risk of tendinitis and tendon rupture that’s further increased in patients >60 years, in patients taking corticosteroid drugs, and in patients with kidney, heart or lung transplants
What are the drug interactions of fluoroquinolones?
Cipro is an inhibitor of CYP4501A2: Theophylline, warfarin, tizanidine, propranolol. Antacids, sucralfate, magnesium, calcium, iron all decrease the absorption of FQs
What are some other features of fluoroquinolones that should be taken into consideration before prescribing?
caution when pt in renal failure, has hepatic dsyfxn, or history of arrhythmias w/QT prolongation. Contains the only oral agents against Pseudomonas
What drugs are sulfonamides?
Sulfamethoxazole/Trimethoprim (SMX-TMP) (Bactrim DS, Septra)
Describe how sulfonamides work?
distribution to body tissue, CSF, pleural fluid, synovial fluid. Eliminated thru liver and kidneys. They’re folic acid synthesis inhibitors.
What diseases can be treated with sulfonamides?
UTIs, PCP or P. jiroveci pneumonia, Toxoplasmosis, MRSA. Not recommened for sinusitis or otitis media due to resistance
What are the most common SE of sulfonamides?
rash (can lead to Stevens-Johnson syndrome), fever, and GI sx
What are drug interactions of sulfonamides?
Potentiates the effects of: Warfarin, Phenytoin, Hypoglycemic agents, Methotrexate
What are some other features of sulfonamides that should be considered before prescribing?
For oral use only. Most commonly used for UTIs. Pregnancy category C. Good for MRSA infections. Don’t use with a sulfa allergy
Describe the use of nitrofurantion (Macrobid)
Only for treatment and prevention of uncomplicated urinary tract infections and who have sulfa allergy. PO
How is nitrofurantion distributed?
rapidly absorbed and only in serum for 30 min.
Inadequate drug levels in the bladder if the creatinine clearance is abnormal (GFR < 60 mL/min). Contraindicated in patients with a creatinine clearance < 60 mL/min
What are the SE associated with nitrofurantion?
most commonly nausea and vomiting. pulmonary rxns, hepatic effects, peripheral neuropathy in long term use of patients w/renal failure
What is the anti-anaerobic antibiotic?
metronidazole (Flagyl)
How is metronidazole absorbed?
Metabolized by the liver. Absorbed well PO. Good tissue penetration in most locations. Half life 6-9 hours
How does metronidazole work?
Causes DNA strand breakage therefore inhibiting bacterial protein synthesis
What is the spectrum of activity for metronidazole?
gram positive and negative anaerobes, H. pylori, Trichomonas vaginalis
What infections is metronidazole the treatment of choice?
Bacterial vaginosis, Trichomoniasis, C. difficile diarrhea
What is the black box warning for metronidazole?
shown to be carcinogenic in mice and rats. Unnecessary use of the drug should be avoided.
What are the SE of metronidazole?
Commonly N/V, abdominal pain, metallic taste. Seizures at high doses. Peripheral neuropathy for prolonged courses. pancreatitis
What are drug interactions of metronidazole?
Enhances anticoagulant effect of warfarin. Alcohol: Flushing, palpitations, nausea, vomiting. Phenobarbital, phenytoin, rifampin increase the metabolism of Flagyl which may lead to treatment failure
