Antifungals 2

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amphotericin B is related to what antibiotics: macrolide
one of the 200 polyene macrolide antibiotics: amphotericin B
MOA for amphotericine B? cidal or static?: Binds ergosterol and creates pores.

Fungicidal
uses for amphotericin B: systemic mycosis

CNS mycosis

Topical for candidiasis
Amphotericin B's more toxic cousin: Nystatin

For topical use only
Administration of amphotericin: emulsified in fat and given IV over 2-4 hours.

Given intrathecally for CNS infection

Not absorbed in GI
Metabolism and excretion of Ampho B: No metabolism

Slowly excreted renally with T-1/2 of 15 days
SE of ampho B: fever, hypotension, tachypnea (give with cortisol or antipyretics)

80% dose-dependent nephrotoxicity

reversible anemia
Drug interaction for Ampho B: Aminoglycosides and Cyclosporin for nephrotoxicity

induces hypokalemia increasing digitalis toxicity

Increase muscular blockade with nicotinic anticholinergics
This drug increases muscular blockade with nictonic anticholinergics: Amphotericin B
MOA Flucytosine: Fungi deaminate it to 5-Flurouracil (mammalian cells don't) and it incorporates into RNA and inhibits thymidate synthetase
Resistance to Flucytosine: Develops Rapidly

Decreased uptake, decreased conversion
Uses for flucytosine: Chromoblastomycosis

With Ampho B for crypto and system candidiasis
ADME Flucytosine: Well absorbed GI
Penetrates CSF
No metabolism
Excreted renal 3-5 hours
Side effects of flucytosine: Dose dependent bone marrow supression
Only used alone for tx of Chromoblastomycosis: Flucytosine
Which azoles has adverse effects with Terfenadine: Ketoconazole and Itraconazole
Erythromycin too

Fluconazol is ok
Ketoconazole use: Broad spect antifungal

Blastomycosis, esophageal candidiasis
Bacteriastatic, so not for gravely ill or immunocompromised patients
ADME Ketoconazole: Adsorbed orally in low acid (antacids and H2 reduce adsorption)

Good distribution, but not to CSF

Excreted in feces
Side effect of ketoconazole: GI

Inhibitis P450
Inhibits steroid and testosterone synthesis (ammenorrhea, gynocomastia)
Drug interaction with Ketoconazole: Rifampin and Pheytoin increase clearance.

Antacids and H2 lower adsorption

Increases effects of anticoagulants

Increases Cyclopsorine and Pheytoin toxicity

Causes arrythmia with Terfenadine
Drug of choice for oral or esophogeal candidiasis: Fluconazole
Uses for Fluconazole: Oral or Esophageal candidiasis

Crytopcoccosis

Not for aspergillosis
ADME of fluconazole: More soluble than keto - oral or IV
Distributes to CSF
No metabolism (no P450 effects)
Renal
Side effects of Fluconazole: Increase Cyclosporine and Pheytoin toxicity

Steve-Johson syndrome, hepatic necrosis

Increase oral anticoagulation
Itraconazole vs ketoconazole: Same except itraconazole has increased effects on sporotrichosis and aspergillosis
ADME for itraconazole: same as ketoconazole

Take with meal

metabolize in liver but excreted in urine (not feces)
Side effect of itraconazole: GI

Arrythmia with Terfenadine

Long QT with high doses

Decreased steroid and testosterone synthesis (P450)
Drug interaction with itraconazole: Isonizaide, Rifampin and Pheytoin decrease its levels

Increases levels of Cyclopsorine, Warfarin, Sulfonyureas, Pheytoin Digoxin
Voriconazole: Fluconazole with aspergillosis coverage

Metabolized by P450 (fluconazole isn't)
Side Effect of Voriconazole: Visual disturbances, CNS effects, rare fulminent hepatitis
This antifungal causes visual disturbances What unique use does it have?: Voriconazole

Treats aspergillosis
Caspofungin and Micafungin: Cell wall inhibitors (glycan)

For oral esophageal candidiasis, aspergillosis and prophylaxis against systemic candidiasis in immune compromised
Nystatin: Cousin of ampho B for topical use only (candidiasis)
Tx for topical dermatophytes: Imidiazole/Triazoles

Like miconazole
Griseofulvin MOA: binds microtubules and inhibits mitosis

Accumulates in keratinocytes which eventually replace infected cells
Use of griseofulvin: For dermatophytes resistant to topical antifungals

Needs 1-12 months
ADME for Griseofulvin: Poorly soluble
Excreted in Urine
Does not accumulate in tissue
Side effects and drug interaction of Griseofulvin: Headaches, GI, reported porphyria

Barbituates decrease absorption

Decreases the effect of oral contraceptives and anticoagulants
Reported cases of hepatotoxicity and intermittend porphyria with this drug: Griseofulvin
Itraconazole is the expensive form of what?: Ketoconazole
Which azoles penetrate the BBB: Only fluconazole
Oral availability differences for azoles: Keto needs acid
Fluconazole well absorbed
Itraconazole needs to given with a meal

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