Antimicrobials - antifungals/ anthelmintic Flashcards
Polyenes include
Amphotericin B
Nystatin
Echinocandins include
Caspofungin
Azoles include
Clotrimazole
Ketoconazole
Fluconazole
itraconazole
posaconazole
voriconazole
Allylamines include
terbinafine
MOA of amphotericin B
IV - disrupts the fungal cell wall synthesis binding to sterols, leading to the formation of pores in the cell membrane, causing K+ to leak out of cell resulting in cell death
What is Amphotericin B used to treat
severe invasive fungal infections - systemic
wide spectrum - widest of all antifungals
last resort - hard for people to tolerate
Amphotericin B onset of action?
rapid; not dependent on organisms growth rate
Amphotericin B kidney affects
nephrotoxicity - vasoconstrictive effect on the afferent renal arterioles, GFR usually returns to normal after cessation of medication
renal tubular acidosis
Amphotericin B adverse reactions
fever and rigors
premedicate with acetaminophen and/or diphenhydramine recommended
N/V
anemia
phlebitis
Flucytosine (5-FC) MOA
inhibits thymidylate synthesis and incorporates into fungal RNA disrupting nucleic acid and protein synthesis
Resistance can occur when fungi decrease level of enzymes targeted
Flucytosine is not used as
monotherapy; used in combo with amphotericin B or itraconazole
Flucytosine and Amphotericin B are used together for treatment in
systemic mycoses and meningitis caused by cryptococcus and candida spp.
Flucytosine and itraconazole are used together for treatment in
chromoblastomycosis infections
when using flucytosine you need to _____ adjust in _____ impairment
dose , renal
flucytosine adverse reactions
reversible neutropenia, thrombocytopenia (lab draws everyday)
dose related bone marrow suppression
reversible hepatic dysfunction
GI upset, N/V, diarrhea - m/c
The azoles are broken up into two different subgroups
imidazoles
triazoles
drugs included in the imidazole group
ketoconazole
miconazole
clotrimazole
more potent, usually topical, too toxic to be used systemically
drugs included in the triazoles group
fluconazole
itraconazole
voriconazole
posaconazole
less potent, usually IV, more systemic sx
the imidazoles MOA
inhibit C-14 alpha-demethylase (CYP450) which disrupts membrane structure
miconazole and clotrimazole are both ______ to be used _____
too toxic
systemically
Ketoconazole can be used _____
systemically
Ketoconazole should not be used with
Amphotericin B
Ketoconazole requires _________ for dissolution and absorption
gastric acid
Antacids and H2 histamine receptor blockers or PPI’s impair absorption of
ketoconazole
Ketoconazole adverse reactions
CYP450
gynecomastia, decreased libido, menstrual irregularities
Contraindications of ketoconazole
pregancy
the triazoles MOA
inhibits synthesis of cell membrane via the fungal CYP450, however does not interfere with the mammalian CYP450 enzymes involved in other steroid hormones - no endocrine side effects
Fluconazole indications
candida, cryptococcus neoformans, coccidiomycosis
Fluconazole does not depend on _______ for absorption
gastric acid
Fluconazole does penetrate the
CSF
Adverse reactions of fluconazole
N/V, rashes, alopecia, hepatitis
Contraindications Fluconazole
pregnancy - teratogenic
Itraconazole indications
histoplasmosis, blastomycosis and sporotrichosis
Itraconazole does require
gastric acid for absorption, no IV formulation
Itraconazole does not
penetrate CSF well
adverse reactions itraconazole
N/V, rash, HA, HTN, hypokalemia, edema, chronic therapy can cause alopecia, rarely hepatitis
Itraconazole drug-drug interactions
warfarin, statins, phenytoin
Contraindications itraconazole
teratogenic
Black box warning itraconazole
do not use for onychomycosis in pts with evidence of CHF or history of CHF
Caspofungin MOA
inhibits B(1,3)-D-glucan synthase, an enzyme involved in fungal cell wall synthesis
Caspofungin indication
invasive aspergillus infection (2nd line)
candidal infections
azole resistant Candida esophagitis
Caspofungin adverse drug reactions
histamine reaction with infusion
drug-drug interactions (cyclosporine, tacrolimus, rifampin)
CNS penetration is poor
Nystatin MOA
binds to ergosterol; similar mechanism to amphotericin B
too toxic for systemic use - never IV
Nystatin is not absorbed in
the GI tract
Nystatin is available in
powder, ointment, cream or suspension
Drug that is excellent for swish and spit or swish and swallow
topical use for skin and/or vaginal infections
Nystatin
Griseofulvin MOA
inhibits mitosis - accumulates in keratin containing tissues
Griseofulvin indications
dermatophytic nail infections
Griseofulvin treatment is required for how long
6-12 months
Griseofulvin should be avoided with
alcohol
increases rate of metabolism of other drugs including anticoagulants
CYP450 enzymes
Terbinafine MOA
inhibits cell wall synthesis by inhibiting fungal squalene epoxidase - decreases synthesis of ergosterol
accumulates in skin, nails and fat
Terbinafine contraindicated
nursing mothers - accumulates in breast milk
Terbinafine adverse reactions
hepatotoxicity - LFTs at baseline
antiprotozoal drugs include
trimethoprim - sulfamethoxazole
metronidazole
antihelmintic drugs include
albendazole
pyrantel pamoate
ivermectin
praziquantel
Metronidazole MOA
activated by anaerobes to metabolites that damage DNA leading to cell death
Metronidazole indications
amebiasis
giardiasis
trichomoniasis
(anaerobic bacterial infections)
Metronidazole adverse reactions
GI upset
metallic taste
seizures
neuropathy
?disulfiram effect with alcohol (sudden desire to vomit)