Drugs Treatment of LUT Infections and STI's (Kinder) Flashcards
what is the MOA of trimethoprim/sulfamethoxazole (TMP/SMX)
sulfonamides are bacteriostatic, competitive inhibitors of dihydropteroate synthase; while synergistic trimethoprim inhibits dihydrofolate reductase.
i) Administering both sulfamethoxazole and trimethoprim inhibits sequential steps in the folic acid pathway. Prevents bacterial use of para-aminobenzoic acid (PABA) for synthesis of folic acid and inhibits final reduction step.
do you need to adjust TMP/SMX in renal impairement
yes
ADR’s of TMP/SMX
allergic skin rashes, nausea, vomiting,
CNS (headache, depression),
photosensitivity,
renal dysfunction, Stevens-Johnson syndrome.
What are the drug-drug interactions of TMP/SMX
inhibits CYP metabolism of drugs → potentiates the effects of warfarin!!
May also increase serum concentrations of digoxin, phenytoin, and others.
May enhance hyperkalemic effect of ACEIs, ARBs, and spironolactone.
MOA of Nitrofurantoin
this is a urinary tract antiseptic
taken PO
drug reduced forming highly reactive intermediates which damage DNA, bacteria reduce drug more rapidly than mammalian cells, thought to account for selective activity.
what are the ADR’s of Nitrofurantoin
nausea, vomiting, diarrhea, macro-crystalline prep better tolerated.
Course of therapy should not exceed 14 days and repeated course should be separated by rest periods.
in what pt’s is nitrofurantoin contraindicated
pregnant women,
impaired renal function (40 mL/min),
children < 1 month.
Methenamine MOA
MOA
decomposes in water to formaldehyde, acidification of urine promotes formaldehyde formation, slow process (requires 3 hours to complete).
not primary drug in UTI but has value in chronic suppressive therapy.
when is methenamine contraindicated
i) Ammonia produced so CI in hepatic insufficiency.
what are the ADR’s of methenamine
GI distress,
painful/frequent micturition,
hematuria,
rash,
low systemic toxicity at usual doses.
Fosfomycin MOA
bactericidal, inhibits very early stage of bacterial cell wall synthesis. Inactivates pyruvyl transferase which leads to reduced formation of N-acetylmuramic acid, which is only found in bacterial cell walls.
what is the t1/2 life of fosfomycin if creatinine clearance is <54 mL/min
50 hours LONG
ADR’s of fosfomycin
c) ADRs: diarrhea, nausea, abdominal pain, headache.
MOA of fluoroquinolones (Ciprofloxacin)
a) MOA: concentration-dependent killing, targets bacterial DNA gyrase and topoisomerase IV.
do you need to adjust fluoroquinolones in renal impairment?
yes
what are the ADRs of fluoroquinolones
GI 3-17% most common (mild nausea, vomiting, abdominal discomfort)
CNS 0.9-11% (mild headache, dizziness, delirium, rare hallucinations)
rash
photosensitivity
Achilles tendon rupture.
MOA of B-lactams
inhibits the transpeptidation reaction, the last step in peptidoglycan synthesis.
Peptidoglycan composed of two alternating sugars (N-acetylglucosamine and N-acetylmuramic acid).
Five-amino-acid peptide linked to final N-acetylmuramic acid which terminates in D-alanyl-D-alanine.
Penicillin binding proteins (PBPs) remove the terminal D-alanine in the process of forming the cross-link.
B-lactams are structural analogs of D-Ala-D-Ala.
B-lactams covalently bind PBPs preventing cross-linking ultimately leading to cell autolysis.
Penicillin G benzathine (B-lactam) ADR’s
allergic reactions (0.7-10%),
anaphylaxis (0.004-0.04%),
interstitial nephritis (rare),
pseudomembranous colitis,
Jarisch-Herxheimer reaction.
what is the drug of choice for susceptible enterococci
Ampicillin (B-lactam)
Ceftriaxone- a cephalosporin (B-lactam)
ADR’s
1% risk of cross-reactivity to penicillins,
injection site reaction,
diarrhea.
***usually reserved for serious infections
MOA of Azithromycin
This is a macrolide
works at 50S
bacteriostatic, binds reversibly to 50S ribosomal subunit, inhibits translocation of newly synthesized peptidyl tRNA molecule from acceptor site on ribosome to peptidyl donor site.
what can reduce the absorption of azithromycin
administration of aluminum and magnesium hydroxide antacids
what are the ADR’s of azithromycin
GI (epigastric distress)
hepatotoxicity
arrhythmia
QT prolongation
in general what are the DDI’s of macrolides
CYP3A4 inhibition – prolongs effects of digoxin, valproate, warfarin, others.
i) Azithromycin structure differs making it less likely to produce DDIs but should use caution.
Metronidazole MOA
: prodrug,
requires reductive activation of nitro groups.
Single electron transfer in anaerobic bacteria forms highly reactive nitro radical anions, kills organisms by radically mediated mechanisms that target DNA.
Increasing 02 inhibits metronidazole as 02 competes for electrons.
what are the ADR’s of metronidazole
: headache, nausea, dry mouth, metallic taste.
Vomiting, diarrhea, abdominal distress occasionally
. Neurotoxic: dizziness, vertigo, very rarely encephalopathy.
Well-reported disulfiram effect → abdominal distress, vomiting, flushing, headache, if alcohol consumed during/within 3 days of drug.
what are the DDI’s of metronidazole
induced metabolism of phenobarbital, prednisone, and rifampin.
Prolongs prothrombin time in those receiving warfarin.
what is a UTI
a) Urinary Tract Infection (UTI): presence of microorganisms within the urinary tract; not due to contamination. Organisms have potential to invade tissues of urinary tract and adjacent structures.
what is an uncomplicated UTI
infection in individuals who lack structural or functional abnormalities of the urinary tract. Occurs in pre-menopausal females of childbearing age (15-45 years) who are otherwise healthy.
why are male UTI’s never uncomplicated?
not considered uncomplicated because these infections are rare and most often a result of a structural or neurological abnormality.
what is a complicated UTI
likely the result of a predisposing lesion (congenital abnormality or distortion), a stone, indwelling catheter, prostatic hypertrophy, obstruction, or neurologic deficit that interferes with the normal flow of urine and urinary tract defenses.
i) Occurs in both genders. Frequently involves upper and lower urinary tracts.
what constitutes a Recurrent UTI?
what accounts for majority of recurrent UTI’s
: in healthy, non-pregnant women; two or more UTIs within 6 months or three or more within one year.
Reinfection– different microorganism than what was originally isolated (accounts for the majority of recurrent UTIs).
what is a relapse of a recurrent UTI
ii) Relapse – same initial organism; usually indicates a persistent infectious source.
UTI organisms usually originate from where
bowel flora
however, virtually every organism can be associated with UTI
what are the organisms involved in uncomplicated infections most often?
E coli- 80-90% of CAI’s
staphylococcus saprophyticus
iii) Klebsiella pneumoniae
iv) Proteus spp.
v) Pseudomonas aeruginosa
vi) Enterococcus spp.