Pharmacology Flashcards
(76 cards)
Tx for HSV
acyclovir, vala-, and fam- = not curative, can decr. symptoms
MOA for acyclovir and vala-
inhibit viral DNA polymerase action (preferentially over host DNA polym.) by inserting into the growing chain and preventing further elongation.
how is acyclovir spec for virally infected cells?
dependant upon viral thymidine kinase for the first of three phosphorylations needed to be active drug.
has 100xs greater affinity for the viral polymerase than the hosts
MOA for famciclovir
metabolized to penciclovir,competitive inhib of viral DNA polymerase, does not cause chain termination (ACV does)
why does ACV have two dosing regimens?
the higher the does of ACV the less its bioavailability, so if you want to increase the dose, you have to give less but more frequently.
Mechanism of resistance to ACV, vala-, fam-
mutation of viral thymidine kinase (70%), or mut of viral DNA polymerase so that it won’t take up the modified bases.
AE of ACV and vala-
access the CNS- neurotoxicity, limited solubility so can precip. in kidneys and cause nephropathy
AE for famciclovir
really none, maybe headache. why isn’t this used then? more expensive and not as well studied as ACV
Tx for syphillis
PCN (the benzathine formulation = IM producing a extended release over 2 weeks)
AE for PCN
hypersens is biggest problem - if pt must be treated, then desensitize and give anyway.
renally excreted - caution in renal problems
jarisch-herxheimer rxn
70-90% of pts w/ 2 syph treated w/ PCN = chills, fever, HA, myalgias and arthralgias, cut. lesions become more brilliant. prob due to rel of spirochete antg. and do not discont. PCN tx.
tx for chlamydia
azithro or doxy (can sub erythro, levofloxacin, ofloxacin)
* assume co-infection w/ GC and give ceftriaxone as well until proven otherwise
contraindications for doxycycline in Ct tx, AE
pregnancy, replace w/ amoxicillan, photosens, hepatic damage in high doses
MOA of azithro, erythro (macrolides)
inhib the 50s ribosomal subunit, bacteriostatic
MOA of doxy (tetracycline)
binds the 30s ribo. subunit, bacteriostatic
MOA of -floxacins
flouroquinolones, inhibit DNA gyrase (topo II), bacteriocidal
levo= gram neg
oflo= gram pos (topo IV)
cipro= both pos and neg
AE of -floxacins
BBW for incr. risk of tendonitis and rupture and musc weakness
Preg cat C - animal studies show damage, not recomm.
Erythromycin AE
CYP inhibitor and P-gp
ceftriaxone, cefixime MOA
3rd gen cephalosporin, bacteriocidal beta lactam- causes cell lysis thru cell wall disruption.
tx for GC
ceftriaxone (IM) or cefixime PLUS Azithro or doxy
- the others are oral.
- azithro and doxy are incl. for coverage of Ct which is presumed present until proven otherwise, also helps reduce devlmpt of resistance in GC
tx for trichomoniasis
metronidazole or tinidazole
MOA for metronidazole, tinidazole
bacterio- ameb- and trichomonacidal, reduced to active form inside the cell and disrupts DNA helix
AE for metro and tinidazole
preg. cat B, not recomm during 1st trimester or breastfeeding, may predispose to malignancy
BV tx
metronidazole (or tinid), or clindamycin