Module 9 14 Antifungals Flashcards
Answer
Question
What are the two major categories of antifungal agents?
Antifungal agents are categorized into drugs for systemic mycoses and drugs for superficial mycoses.
What distinguishes systemic mycoses from superficial mycoses in terms of frequency and severity?
Systemic mycoses are less frequent but more severe than superficial mycoses.
What is the primary focus of this summary regarding antifungal therapy?
This summary primarily focuses on the therapy of systemic mycoses.
What are the two categories of systemic mycoses?
Systemic mycoses are categorized into opportunistic and nonopportunistic infections.
Who is primarily affected by opportunistic mycoses?
Opportunistic mycoses, including candidiasis, aspergillosis, cryptococcosis, and mucormycosis, primarily affect debilitated or immunocompromised individuals.
Which individuals can be affected by nonopportunistic mycoses?
Nonopportunistic mycoses, such as sporotrichosis, blastomycosis, histoplasmosis, and coccidioidomycosis, can affect any host but are relatively uncommon.
Why is treating systemic mycoses challenging?
Treating systemic mycoses can be challenging because these infections often resist treatment and may require prolonged therapy with potentially toxic drugs.
Where can you find information on the drugs of choice for systemic mycoses?
Table 79.1 provides a list of the drugs of choice for systemic mycoses.
What are the four classes of systemic antifungal drugs?
The four classes of systemic antifungal drugs are polyene antibiotics, azoles, echinocandins, and pyrimidine analogs.
What are the causative organisms for aspergillosis?
Aspergillosis is caused by Aspergillus spp.
What is the drug of choice for aspergillosis?
The drug of choice for aspergillosis is voriconazole.
What are the alternative drugs for treating aspergillosis?
Alternative drugs for aspergillosis include amphotericin B, isavuconazonium, itraconazole, posaconazole, caspofungin, and micafungin.
What is the causative organism for blastomycosis?
Blastomycosis is caused by Blastomyces dermatitidis.
What are the drugs of choice for treating blastomycosis?
The drugs of choice for blastomycosis are amphotericin B or itraconazole.
Is there an alternative recommended treatment for blastomycosis?
No alternative treatment is recommended for blastomycosis.
What is the causative organism for candidiasis?
Candidiasis is caused by Candida spp.
What are the drugs of choice for treating candidiasis?
The drugs of choice for candidiasis are amphotericin B or fluconazole, either one, with or without flucytosine.
What are the alternative drugs for treating candidiasis?
Alternative drugs for candidiasis include itraconazole, voriconazole, and caspofungin.
What is the causative organism for coccidioidomycosis?
Coccidioidomycosis is caused by Coccidioides immitis.
What are the drugs of choice for treating coccidioidomycosis?
The drugs of choice for coccidioidomycosis are amphotericin B or fluconazole.
What are the alternative drugs for treating coccidioidomycosis?
Alternative drugs for coccidioidomycosis include itraconazole and ketoconazole.
What is the causative organism for cryptococcosis?
Cryptococcosis is caused by Cryptococcus neoformans.
What are the drugs of choice for treating cryptococcosis?
The drugs of choice for cryptococcosis are amphotericin B with or without flucytosine.
What is the drug used for chronic suppression of cryptococcosis?
For chronic suppression of cryptococcosis, fluconazole is the drug of choice.
What is the causative organism for histoplasmosis?
Histoplasmosis is caused by Histoplasma capsulatum.
What are the drugs of choice for treating histoplasmosis?
The drugs of choice for histoplasmosis are amphotericin B or itraconazole.
What are the alternative drugs for treating histoplasmosis?
Alternative drugs for histoplasmosis include fluconazole and ketoconazole.
What is the drug used for chronic suppression of histoplasmosis?
For chronic suppression of histoplasmosis, itraconazole is the drug of choice.
What is the causative organism for mucormycosis?
Mucormycosis is caused by Mucor.
What is the drug of choice for treating mucormycosis?
The drug of choice for mucormycosis is amphotericin B.
What is the alternative drug for treating mucormycosis?
The alternative drug for mucormycosis is isavuconazonium.
What is the causative organism for sporotrichosis?
Sporotrichosis is caused by Sporothrix schenckii.
What are the drugs of choice for treating sporotrichosis?
The drugs of choice for sporotrichosis are amphotericin B or itraconazole.
What is the alternative drug for treating sporotrichosis?
The alternative drug for sporotrichosis is fluconazole.
How are the systemic antifungal drugs classified?
Systemic antifungal drugs are classified into polyene antibiotics, azoles, echinocandins, and pyrimidine analogs.
What is the mechanism of action of polyene antibiotics in treating fungal infections?
Polyene antibiotics bind to ergosterol and disrupt the fungal cell membrane.
Name a representative drug from the polyene antibiotic class used to treat fungal infections.
Amphotericin B is a polyene antibiotic used to treat fungal infections.
What is the mechanism of action of azoles in treating fungal infections?
Azoles inhibit the synthesis of ergosterol and disrupt the fungal cell membrane.
Provide examples of azole drugs used to treat fungal infections.
Azole drugs used to treat fungal infections include fluconazole, isavuconazonium, itraconazole, ketoconazole, posaconazole, and voriconazole.
How do echinocandins work in the treatment of fungal infections?
Echinocandins inhibit the synthesis of β-1,3-d-glucan and disrupt the fungal cell wall.
Name some representative drugs from the echinocandin class used for fungal infection treatment.
Representative drugs from the echinocandin class include anidulafungin, caspofungin, and micafungin.
What is the mechanism of action of pyrimidine analogs in treating fungal infections?
Pyrimidine analogs disrupt the synthesis of RNA and DNA.
Give an example of a pyrimidine analog used for treating fungal infections.
Flucytosine is a pyrimidine analog used to treat fungal infections.
Which drug class does Amphotericin B belong to, and why is it called “polyene antibiotics”?
Amphotericin B belongs to the polyene antibiotics drug class, named for the presence of conjugated double bonds in their structures.
What is the spectrum of activity for Amphotericin B in terms of fungal infections?
Amphotericin B is active against a broad spectrum of pathogenic fungi.
What are some common side effects or toxicities associated with Amphotericin B?
Common side effects of Amphotericin B include infusion reactions and renal damage.
In which cases should Amphotericin B be used for treating fungal infections?
Amphotericin B should be employed only for infections that are progressive and potentially fatal and are unresponsive to other treatments.
How many formulations of Amphotericin B are available, and what makes the lipid-based formulations different?
There are four formulations of Amphotericin B, with the lipid-based formulations being less toxic but more expensive.
What is the typical route of administration for all formulations of Amphotericin B, and how is it administered?
All formulations of Amphotericin B are administered by intravenous (IV) infusion.
What is the usual treatment regimen for Amphotericin B in the context of systemic mycoses?
Treatment with Amphotericin B typically involves daily or every other day infusions for several months.
How does Amphotericin B affect fungal cells at the membrane level?
Amphotericin B binds to components of the fungal cell membrane, increasing membrane permeability, which leads to the leakage of intracellular cations and reduced cell viability.
Can Amphotericin B have fungistatic or fungicidal effects, and what factors determine this?
Amphotericin B can have fungistatic or fungicidal effects, depending on its concentration and the susceptibility of the fungus being treated.
What component of the fungal membrane does Amphotericin B bind to, and why is this important for susceptibility?
Amphotericin B binds to ergosterol, a sterol in the fungal cell membrane. Fungal cells must contain sterols like ergosterol to be susceptible to Amphotericin B.
Why are bacterial cells unaffected by Amphotericin B?
Bacterial membranes lack sterols, such as ergosterol, making them unaffected by Amphotericin B.
What causes the toxicity of Amphotericin B in mammalian cells, and why does some selectivity exist?
The toxicity of Amphotericin B in mammalian cells is primarily due to the presence of sterols, particularly cholesterol, in their membranes. There is some selectivity because Amphotericin B binds more strongly to ergosterol in fungal membranes than to cholesterol in mammalian membranes.
Which microorganisms are susceptible to Amphotericin B?
Amphotericin B is effective against a broad spectrum of fungi and certain protozoa like Leishmania braziliensis.
Are bacteria susceptible to Amphotericin B?
Bacteria are resistant to Amphotericin B.
How often does the emergence of resistant fungi occur with Amphotericin B use, and what is associated with fungal resistance?
The emergence of resistant fungi due to Amphotericin B use is extremely rare and usually only happens with long-term usage. Fungal resistance is associated with reduced or absent amounts of ergosterol in their membranes, which is the drug’s target.
What are the primary uses of Amphotericin B?
Amphotericin B is the drug of choice for most systemic mycoses (systemic fungal infections) and is also used for the treatment of leishmaniasis.
How did systemic fungal infections fare before the availability of Amphotericin B?
Systemic fungal infections were often fatal before the availability of Amphotericin B.
What is the typical duration of treatment with Amphotericin B for systemic mycoses?
The treatment duration with Amphotericin B is usually prolonged, lasting 6 to 8 weeks, but in some cases may extend to several months.
Why can’t Amphotericin B be administered orally for systemic infections?
Amphotericin B is poorly absorbed from the gastrointestinal (GI) tract, rendering oral therapy ineffective for systemic infections.
How is Amphotericin B typically administered for systemic infections?
Amphotericin B is administered intravenously for systemic infections.
What happens when Amphotericin B leaves the vascular system in the body?
After leaving the vascular system, Amphotericin B binds extensively to tissues containing sterols.
In which body fluids does Amphotericin B achieve approximately half the plasma levels?
Amphotericin B reaches about half the plasma levels in aqueous humor, peritoneal, pleural, and joint fluids.
What is the current understanding of amphotericin B’s elimination from the body?
Little is known about the elimination of amphotericin B, and it is unclear whether the drug undergoes metabolism or is eventually removed from the body.
How is amphotericin B primarily eliminated from the body?
Renal excretion of unchanged amphotericin B is minimal.
When might dose or frequency reduction be considered for amphotericin B treatment?
Patients with preexisting renal impairment may require dose or frequency reduction during amphotericin B treatment.
How long does it take for complete elimination of amphotericin B from the body?
Complete elimination of amphotericin B is a slow process, with the drug detectable in tissues for more than a year after treatment cessation.
What are some of the serious adverse effects associated with amphotericin B?
Amphotericin B can cause a variety of serious adverse effects.
In what setting should patients receiving amphotericin B be supervised?
Patients receiving amphotericin B should be closely supervised, preferably in a hospital.
Why is amphotericin B used cautiously?
Amphotericin B is highly toxic.
In what circumstances is amphotericin B typically prescribed?
Amphotericin B is primarily used in the setting of potentially life-threatening fungal infections due to its toxicity.
What adverse reactions are common during intravenous amphotericin B administration?
Fever, chills, rigors, nausea, and headache are common adverse reactions during intravenous amphotericin B administration.
What causes these adverse reactions?
These reactions are caused by the release of proinflammatory cytokines from immune cells.
When do the symptoms of these reactions typically start, and how long do they last?
Symptoms usually begin 1 to 3 hours after starting the infusion and last for about an hour.
How can mild reactions be managed?
Mild reactions can be managed with premedication like diphenhydramine and acetaminophen.
When might hydrocortisone be used, and why should its routine use be avoided?
Hydrocortisone may be used in cases where other measures fail to reduce fever and chills. Its routine use is discouraged because it can weaken the patient’s ability to fight infections.
Are lipid-based amphotericin formulations associated with fewer infusion reactions?
Yes, lipid-based amphotericin formulations cause fewer and less intense infusion reactions than the conventional formulation.
How can the incidence of phlebitis during amphotericin infusion be minimized?
The incidence of phlebitis can be reduced by changing venous sites often, administering amphotericin through a large central vein, and using heparin as pretreatment.
Why does renal impairment occur in practically all patients receiving amphotericin B?
Renal impairment occurs because amphotericin B is toxic to kidney cells.
What factors determine the extent of kidney damage caused by amphotericin B?
The extent of kidney damage is related to the total dose of amphotericin B administered during the full course of treatment.
What typically happens to renal function after discontinuing amphotericin use?
In most cases, renal function normalizes after discontinuing amphotericin use.
When is residual kidney impairment likely to occur, and how can it be minimized?
Residual kidney impairment is likely if the total amphotericin dose exceeds 4 grams. Kidney damage can be minimized by infusing 1 liter of saline on amphotericin administration days and avoiding other nephrotoxic drugs.
How often should tests of kidney function be performed during amphotericin treatment, and what parameters should be monitored?
Kidney function tests should be performed every 3 to 4 days. Parameters to monitor include plasma creatinine content and fluid intake and output.
At what plasma creatinine content should amphotericin dosage be reduced?
Amphotericin dosage should be reduced if plasma creatinine content rises above 3.5 mg/dL.
Is the degree of renal damage different between lipid-based amphotericin formulations and the conventional formulation?
Yes, the degree of renal damage is less with lipid-based amphotericin formulations compared to the conventional formulation.
What is the potential bone marrow-related adverse effect of amphotericin B?
Amphotericin B can cause bone marrow suppression.
What type of anemia can result from bone marrow suppression due to amphotericin B?
Bone marrow suppression from amphotericin B can result in normocytic, normochromic anemia.
How should the status of red blood cells be monitored during amphotericin B treatment?
Hematocrit determinations should be conducted to monitor the red blood cell status.
What happens when amphotericin is used with other nephrotoxic drugs like aminoglycosides, cyclosporine, or NSAIDs?
The risk of kidney damage increases.
What is the recommended course of action when considering combinations of amphotericin with nephrotoxic drugs?
It is advisable to avoid such combinations whenever possible to reduce the risk of kidney damage.
How do azoles compare to amphotericin B in treating systemic fungal infections?
Azoles serve as an alternative to amphotericin B with lower toxicity and oral administration.
What is a disadvantage of azoles in terms of drug interactions?
Azoles inhibit hepatic cytochrome P450 drug-metabolizing enzymes, potentially increasing the levels of other drugs.
Which azoles are indicated for systemic mycoses?
Itraconazole, ketoconazole, fluconazole, voriconazole, posaconazole, and isavuconazonium.
What are the therapeutic uses of Itraconazole (Sporanox)?
Blastomycosis, histoplasmosis, paracoccidioidomycosis.
How is Itraconazole available for administration?
100-mg capsules and a 10-mg/mL solution.
What is the usual adult dose for Itraconazole?
200 mg 1–2 times daily.
What is the main adverse effect associated with Itraconazole?
Cardiac suppression and liver injury.
For which conditions is Fluconazole (Diflucan) used?
Blastomycosis, candidiasis, histoplasmosis.
How is Fluconazole (Diflucan) available for administration?
Tablets (50-, 100-, 150-, 200-mg), suspension (10-mg and 40-mg/mL), and a solution for IV injection.
What are the adverse effects of Fluconazole (Diflucan)?
Nausea, headache, and Stevens-Johnson syndrome.
What is the main therapeutic use of Voriconazole (Vfend)?
Aspergillosis, candidiasis, histoplasmosis.
How is Voriconazole (Vfend) available for administration?
Tablets (50-, 200-mg), suspension (40-mg/mL), and a solution for IV injection.
What are the primary adverse effects associated with Voriconazole (Vfend)?
Hepatotoxicity, visual disturbances, and hypersensitivity reactions.
What is the role of Ketoconazole in treating systemic mycoses?
Ketoconazole is used for histoplasmosis, blastomycosis, and coccidioidomycosis.
What is Itraconazole (Sporanox)?
Itraconazole is an azole antifungal drug.
What role does Itraconazole play in treating systemic mycoses?
It serves as an alternative to amphotericin B for several systemic mycoses.
What are the advantages of using Itraconazole?
It is safer than amphotericin B and can be administered orally.
What are the principal adverse effects associated with Itraconazole?
Cardiosuppression and liver injury.
How can Itraconazole affect the levels of other drugs?
Like other azoles, itraconazole can inhibit drug-metabolizing enzymes, potentially raising the levels of other drugs.
What is Amphotericin B, and which class of antifungal drugs does it belong to?
Amphotericin B is a polyene macrolide, and it belongs to the polyene antibiotic class.
How does Amphotericin B work to combat fungal infections?
It binds to ergosterol in fungal cell membranes, disrupting them and causing leakage of intracellular cations, which can be fungistatic or fungicidal.
What is Amphotericin B commonly used for in the context of fungal infections?
It is used for most systemic mycoses, but it’s known for its high toxicity.
What is Itraconazole, and what role does it play in treating systemic mycoses?
Itraconazole is an azole antifungal drug that serves as an alternative to amphotericin B for systemic mycoses.
What are the advantages of using Itraconazole?
Itraconazole is safer than amphotericin B and can be administered orally.
What is the potential downside of using Itraconazole concerning other medications?
Like other azoles, itraconazole can inhibit drug-metabolizing enzymes, potentially affecting the levels of other drugs.
What is Caspofungin, and which class of antifungal drugs does it belong to?
Caspofungin is an echinocandin, belonging to the echinocandin class of antifungal drugs.
How does Caspofungin work against fungal infections?
Caspofungin inhibits the synthesis of β-1,3-d-glucan in fungal cell walls.
What are the typical uses of Caspofungin in the context of fungal infections?
It is used for conditions like aspergillosis, candidiasis, and histoplasmosis.
How does Itraconazole affect the synthesis of ergosterol in fungal cells?
Itraconazole inhibits ergosterol synthesis, leading to increased membrane permeability and the leakage of cellular components.
What is the primary mechanism by which Itraconazole suppresses ergosterol synthesis?
Itraconazole works by inhibiting fungal cytochrome P450-dependent enzymes, which are essential for ergosterol production.
Which fungal infections is Itraconazole a preferred treatment for?
Itraconazole is the drug of choice for blastomycosis, histoplasmosis, paracoccidioidomycosis, and sporotrichosis.
In what cases can Itraconazole be an alternative to amphotericin B for treatment?
Itraconazole can be an alternative to amphotericin B in cases of aspergillosis, candidiasis, and coccidioidomycosis.
Besides systemic mycoses, what other type of fungal infections can Itraconazole be used to manage?
Itraconazole can also be used for superficial mycoses.
How is Itraconazole typically administered?
Itraconazole is usually administered orally, either in the form of capsules or suspension.
What effect does taking Itraconazole with food have on its absorption, and does this apply to both capsules and suspension?
Taking Itraconazole with food enhances the absorption of capsules but decreases the absorption of the suspension.
What is the impact of taking Itraconazole with cola?
Interestingly, taking Itraconazole with cola can enhance its absorption.
In which type of tissues is Itraconazole widely distributed?
Itraconazole is distributed widely in lipophilic tissues.
Does Itraconazole reach significant concentrations in aqueous fluids like saliva and cerebrospinal fluid?
No, the concentrations of Itraconazole in aqueous fluids are negligible.
How is Itraconazole metabolized in the body?
Itraconazole undergoes extensive hepatic metabolism.
What happens to approximately 40% of each Itraconazole dose in the body?
About 40% of each Itraconazole dose is excreted in the urine as inactive metabolites.
How is Itraconazole typically tolerated at usual doses?
Itraconazole is generally well-tolerated at standard doses.
What are the most common adverse reactions associated with Itraconazole?
The most common adverse reactions include gastrointestinal symptoms like nausea, vomiting, and diarrhea.
Besides gastrointestinal symptoms, what are some other potential side effects of Itraconazole?
Other potential side effects may include rash, headache, abdominal pain, and edema.
Name two potentially serious effects that can be associated with Itraconazole.
Itraconazole may lead to cardiac suppression and liver injury, both of which can be serious.
What cardiac effect can Itraconazole have?
Itraconazole can cause a transient decrease in ventricular ejection fraction, affecting the heart’s pumping ability.
Is the cardiac effect of Itraconazole permanent?
No, the reduction in cardiac function is temporary, and it typically returns to normal within 12 hours after dosing.
Can Itraconazole be used in patients with heart failure to treat serious fungal infections?
Yes, it can be used in such patients, but it should be administered with careful monitoring.