Sulfonamides,trimethoprim and quinolones 12/17 Flashcards
(26 cards)
sulfonamides
structural analogs of PABA (para-aminobenzoic acid)
MOA of sulf.
competitively inhibit conversion of PABA to folic acid mediated by the enzyme dihydropteroate synthase
bacteriostatic
antimicrobial spectrum of sulf.
G+,G-,chlamydia and nocardia
mechanisms of resistance for sulf.
microbial overproduction of PABA
structural changes that occur in bacterial dihydropteroate synthase
decreased permeability
pharmacokinetics of sulf.
high oral bioavailability
distributed in most tissues (CSF)
acetylation in liver. product has no AB activity but retains toxic potential of parent drug
excreted in urine by glomerular filtration
Topical
silver sulfadiazine:burns
sulfacetamide:conjunctivitis,corneal ulcer,other ocular infx
triple sulfa:vaginitis caused by hemophilus vaginalis
Oral sulf. (few indications for use of oral agents alone)
sulfasoxazole: uncomplicated UTI
sulfamethoxazole: combined with trimethoprim for uncomplicated UTI
sulfadoxine/pyramethamine:malaria.sulfadoxine is very long acting
sulfadiazine/pyramethamine:toxoplasmosis
dapsone: leprosy (with others)
sulfasalazine: not absorbed,active ingredient is 5-aminosalicylic acid.inflammatory bowel disorder
AE of sulf
topical: irritation,burning
oral: hypersens.,n/v/d,crystaluria,hemolytic anemia in pts wit G-6-P dehydrogenase deficiency,kernicterus in newborn (due to significant plasma protein binding and displacement of biliruben)
Also displacement of warfarin increasing its levels
trimethoprim
inhibits dihydrofolate reductase of bacteria>mammalian cells. Methotrexate is not selective
bacteriostatic
pharmacokinetics of trimethoprim
high oral bioavailability
well distributed in tissues (CSF)
most excreted unchanged in urine
Uses of trimethoprim alone
uncomplicated UTI
uses of trimethoprim/sulfamethoxazole
PO: pneumonia due to pneumocystis carinii
GI infx:shigella,enteritis
systemic infx:nocardia,salmonella
UTI and resp infx by H.influenzae or S.pneumonae
Listeria meningitis
IV:pneumocystis carinii pneumonia
AE of TMP-SMX
rare hematopoietic disturbances
use folinic acid to prevent
MOA of quinolones
inhibit topoisomerase II (DNA gyrase) and topoisomerase IV
prevents unwinding of supercoiled DNA required for transcription and duplication
inhibition of topoisomerase IV interferes with separation of replicated chromosomal DNA
minimal effect on mammalian enzyme
resistence against quinolones
modification of DNA gyrase or topoisomerase IV structure
alteration of membrane permeability into bacterial cell
pharmacokinteics of quino.
well absorbed orally (norfloxacin is lowest)
food+antacids decrease bioavailability
widely distributed
plasma protein binding is low
most is eliminated through urine by filtration and proximal tubular secretion (which is inhibited by probenecid)
Uses of quinol. topical
eye
ciprofloxacin for conjuctivitis,corneal ulcer
most fluroquinolones are used orally
resistant UTI (cipro and levo)
osteomyelitis and cellulitis(levo,moxi,gemi)
infectious diarrhea and typhoid fever
single dose Tx for gonorrhea(cipro and levo)
pseudomonas(cipro and levo)
Anthrax(cipro and levo)
levofloxacin,gemifloxacin,moxifloxacin
resp tract infx and community acquired pneumonia
reserved for pts with comorbid/risk factors
Cipro
available IV
Local AE of quinol.
irritation,stinging,burning
systemic AE of quinolones
n/v/d
may damage growing cartilage–> not recommended for pregnant women or kids.can cause tendonitis
some can prolong QT.avoid with other antiarrythmic
CRANK to remember AE of sulfonamides
Crystalluria
Rashes
Anemia
Nausea
Kernicterus
Pts who are at risk of getting pneumocystis pneumonia and have allergy to sulfa drugs–>
give ATOVAQUONE
collapses mitochondrial membrane potential
use with caution in pts with renal impairment
caution in pregnancy
abd pain,n/v,headache
