Antifungal Drugs - Ch. 92 Flashcards
Fungi
-Large and diverse group of micro-organisms
-Broken down into yeasts and moulds
What is the term used for fungal infections?
Mycoses
Where can fungal infections develop?
Normal flora of the skin, mouth, intestines, vagina (just like bacteria)
There is a rise in which kind of fungal infections?
Opportunistic
-Broad-spectrum antibiotics causing less competition
How are Mycotic (fungal) infections classified?
Superficial
Systemic
Where do superficial mycotic (fungal) infections occur?
Integumentary
Mucous membranes
What are systemic mycotic infections?
Can be life-threatening
May require prolonged drug therapy that can be toxic
Occur in immunocompromised hosts
What is Candida albicans?
Common yeast
Why are immunocompromised patients more likely to get a candida infection?
Antibacterial therapy, antineoplastics or immunosuppressents increase their risk
What can result from a Candida albicans infection in an immunocompromised patient?
May result in overgrowth and systemic infections
What are some parts of the body Candida albicans infects?
Mouth mucous membranes
Vagina
What is is called when there is an infection of candida in the mouth?
Oral candidiasis or thrush
What is it called when there is vaginal candidiasis?
Yeast infection
What things can make you more susceptible to Candida infections?
Pregnancy
Diabetes Mellitus
Oral contraceptives
What are dermatomycoses?
Tinea/ringworm
-Affects skin, nails and hair
What are the main subgroups of antifungals?
Naturally occuring
Synthetic
Which antifungals belong to the naturally occurring group?
Polyenes
Echinocandins
Which antifungals belong to the synthetic group?
Azoles
Pyrimidines
Examples of Polyenes?
Amphotericin B
nystatin
Examples of Azoles?
Fluconazole
-miconazole, clotrimazole, ketoconazole,
itraconazole
What can be used to treat systemic fungal infections?
Amphotericin B
Fluconazole, ketoconazole, itraconazole
How is Amphotericin B administered?
SLOW IV injection
Lipid and non-lipid preparations
How is Fluconazole, ketoconazole, itraconazole administered?
Multiple administration routes
What is used to treat superficial fungal infections?
Nystatin
Azoles like fluconazole, ketoconazole, clotrimazole,
miconazole
What find of superficial infections are treated via Nystatin?
Oral infections
How is Nystatin administered?
Suspension should be swished in the mouth as long as possible before swallowing
How is azoles for superficial infections administered?
PO/topical
for vaginal candidiasis, skin infections (tinea)
What is the mechanism of action of Polyenes: amphotericin B and nystatin?
Binds to sterols in cell membrane
Makes hole sin fungi cell membranes
Fungal cell death (mostly)
What do higher concentrations of Polyenes do?
Bind to cholesterol of human cells to cause toxicities
What is the mechanism of action of Azoles: fluconazole, ketoconazole, miconazole, clotrimazole?
Inhibit sterol-altering enzyme
-Cyp P450 enzymes which cause less ergosterol in fungi membranes
Leads to altered cell membrane
Inhibits growth/kills cells
What is the antifungal agent of choice for the treatment of severe systemic mycoses?
Amphotericin B
-Azoles = alternative
Amphotericin has many what?
Many adverse effects
What are the main concerns (adverse effects) of amphotericin B?
Renal toxicity (K+ loss)
Impairs hepatic functions
Assess which functions before amphotericin B administration.
Liver and kidney functions
What are the other adverse effects of Amphotericin B?
fever
headache
malaise
hypotension
muscle and joint pain
chills
dysrhythmias
Nausea and vomiting
Anorexia
What is a patient pretreated with to reduce the severity of the amphotericin B infusion-related reactions?
Antipyretic (acetaminophen)
Antihistamines (diphenhydramine)
anti-emetics
-test dose is given to assess the reaction
Many azoles inhibit which enzymes?
Hepatic CYP enzymes
What may the co-administration of two drugs metabolized by the hepatic system result in?
Competition for hepatic CYP enzymes
-Higher levels of one of the drugs
