Antifungals, antimycobacterials, antivirals Flashcards
What’s a genus of bacteria that includes many species of pathogens?
mycobacterium
What are the targets of antimycobacterials?
enzymes that mycobacteria use to build their cell walls
How are mycobacteria different than typical bacteria?
easier to control but harder to treat because they replicate slower.
CAN exist in a dormant state which makes them resistant to nearly all abx
What’s the standard treatment in active mycobacterial disease?
- Rifampin
- Isoniazid
- Pyrazinamide
- Ethambutol
Note: takes weeks to get susceptibility results
How does isoniazid work?
- bactericidal
- inhibits mycolic acid synthesis!
- effective against active AND dormant TB
- acts as a weak MAO-I (careful with SSRI/SNRI)
- alters pyridoxine metabolism (give B6 to all patients)
What are the two most important drugs for TB?
- isoniazid
- rifampin
What is isoniazid active against?
M. tuberculosis and M. kansasii
How is isoniazid clinically utilized?
mycobacterial infections
When is isoniazid your DOC?
latent TB, active TB
What are ADRs of isoniazid?
hepatotoxicity, peripheral neuropathy (use pyridoxine), hemolysis in G6PD deficiency
What are examples of rifamycins?
- rifampin
- rifabutin
- rifapentine
- rifaximin
What’s the MOA of rifamycins?
- bactericidal
- Inhibits DNA-dependent RNA polymerase
- very good oral bioavailability
- resistance emerges when drug is used alone
What should you always screen for drug ineractions?
rifamycins – extremely potent CYP450 inducers!!
also, reduced effectiveness of oral contraceptives
What are rifamycins GOOD for?
mycobacteria
What are rifampins moderate for?
staph, acinetobacter, enterobacterciae
What are rifamycins utilized for?
mycobacterial infections – usually in combo w/ deep seeded “typical” bacterial infections (MRSA) or if prosthetic material
When is rifamycin your DOC?
TB = tuberculosis, MAC = mycobacterium avium complex
What are ADRs of rifamycins?
orange-red colored secretions (urine, tears)
Do rifamycins have DIs?
many due to enzyme induction
What’s the MOA of pyrazinamide?
- bacteriostaticuncertain but requires bioactivation via hydrolytic enzymes to form pyrazoic acid
- shortens duration 9m - 6m
NOT pyridoxine
AVOID IN PREGNANCY
When are pyrazinamides clinically active?
M. tuberculosis
When are pyrazinamide clinically utilized and is your DOC?
active TB
What are the ADRs of pyrazinamide?
polyarthralgia (40%), hyperuricemia, mylagia, maculopapular rash, porphyria, photosensitivity
What’s the MOA of ethambutol?
- bacteriostatic
- inhibits formation of arabinoglycan, component of mycobacterial cell wall
- only 1st 2 months of tuberculosis therapy
- **NOT recommended in children <5yo **
When is ethambutol clinically active and utilized?
- M. tuberculosis, M. avium-intracellulare, M. kansaii
- active TB and MAC infections
What are ADRs of ethambutol?
- dose-dependent visual disturbances
- headache
- confusion
- hyperuricemia
- peripheral neuritis
- difficulty deferentiating from red and green
What are the increase of systemic fungal ifnections a consequence of?
medical advancement
What are types of moulds?
aspergillus (a. fumigatus, mucor spp, rhizopus spp)
dermatophytes
What are types of yeasts?
candida (C.albicans)
cryptococcus (C.neoformans, C. gattii)
Malassezia (M. furfur)
What are dimorphic fungi?
histoplasma capsulatum
coccidioides immitis
sporothirix schenkii
blastomyces
Imidazoles: COMET-K
Clotrimazole
Oxiconazole
Miconazole
Econazole
Tioconazole
Ketoconazole
Triazoles: FIT VIP
Fluconazole
Itraconazole
Teraconazole
Voriconazole
Isavuconazole
Posaconazole
Allyamines: TAN
Terbinafine
Amorolfin
Naftifine
Echinocandins: MAC
Micafungin
Anidulafungin
Caspafungin
What are examples of polyenes?
amphotericin B, nystatin
What is the MOA of polyenes?
- fungicidal/fungistatic (dependent)
- binds to ergosterol in fungal cell membranes, forming leaky pores
What’s used to decrease polyene side effects?
lipid formulations and different dosing dependent
What are ADRs of polyenes?
nephrotoxicity, infusion reactions (chills, fever, muscle spasms, hypotension), electrolyte abnormalities (hypokalemia)
When do polyenes have good coverage?
candida and aspergillus, cryptococcus neoformans, dimorphic fungi, molds
When do polyenes have moderate coverage?
zygomycetes
When are polyenes clinically utilized?
unknown fungal infections, use for candidiasis and aspergillosis (less often with newer/safer agents)
When are polyenes your DOC?
cryptococcal meningitis and serious dimorphic fungi and mold infections
What are DIs with polyenes?
nephrotoxic drugs (additive)
What are examples of azoles?
fluconazole, itraconazole, voriconazole, ketoconazole
What’s the MOA of azoles?
- fungicidal and fungistatic (dependent)
- inhibits fungal P450 dependent enzymes blocking ergosterol synthesis
- mainstays of antifungal therapy
What’s the ADRs of azoles?
hepatotoxicity, Qtc prolongation, rash, upset stomach
What DIs do azoles have?
many – inhibits CYP450
Which is the only azole with significant utility in candiduria?
fluconazole