AntiFungals Flashcards
3 Forms of Fungi
- Yeast (Ex. Candidia)
- Dimorphic fungi (Ex. histoplasmosis)
- Molds (Ex. Aspergillus)
Antifungal medications
- Azoles
- Clotrimazole
- fluconazole
- ketoconazole
- miconazole
- terconazole
- efinaconazole - Polyenes
- Nystatin - Other
- Terbinafine
Azoles
Mechanism of action
Inhibition CYP450
Inhibit synthesis of ergosterol (required for cell membrane)
Disrupt fungal cell membrane
Polyene
Mechanism of action
Binds to ergosterol and disrupts the fungal cell membrane
Fungal cell membrane leaks cations (potassium)
SE of Azoles
Prolonged QT interval
Cardiac suppression (Fatal - Irtaconazole)
Hepatic necrosis (Fatal - Ketoconazole)
Stephen Johnsons Syndrome, hypersensitivities
Nausea, vomiting, HA, visual disturbances
Rashes, topical irritation and erythema
Azole contraindications
Cardiac disease (QT interval, Irtaconozole - cardiac supression)
Liver disease (Ketoconazole)
Pregnancy (Avoid systemic antifungals)
Do not breast feed on ketoconazole due to hepatotoxicity
Azole Drug interactions
Inhibits CYP3A4
- phenytoin, carbamazepine, warfarin, digoxin toxicity
Azole Monitoring
Assess for
- pregnancy
- liver disease
- cardiac disease
Pre-monitoring
- Liver enzymes
- ECG for QT interval (or QT prolonging drugs)
Education
- Monitor for S&S of liver failure, rash/SJS,
Azole coverage
Systemic and superficial mycoses infections
Ketoconazole - systemic mycoses in patients not tolerant of amphotericin B
Fluconazole - candidiasis, histoplasmosis (yeast and dimorphic)
Irtaconazole - aspergillus, histoplasmosis/blastomycosis (molds and dimorphic)
Polyene antibiotics
Nystatin PO
Amphotericin B (IV)
Amphotericin B mechanism of action
Binds ergosterol
disrupts fungal cell membrane, leaks
Amphotericin B SE
All patients experience
- Infusion reactions
- Fever, chills, nausea, HA
Pre-treatment with : diphenhydramine and tylenol
- Renal toxicity
- Total dosage < 4g
Pre-treatment with:
1L NS during infusion
- Bone marrow supression
*Stays in body years later
Amphotericin B pre-treatment and monitoring
CBC
WBC
CrCl and BUN
SE:
- Bone marrow suppression
- renal toxicity
Acetaminophen
1L NS
SE:
Infusion reaction rigors, fever, HA and nephrotoxicity
Alternative prescription if the patient does not tolerate amphotericin
Ketoconazole PO
Monitor for fatal hepatotoxicity
Amphotericin B drug interactions and contraindications
Caution in prescribing nephrotoxic drugs
- NSAIDS
- glucocorticoids/cyclosporins
- nephrotoxic antibiotics (Ex. vancomycin, aminoglycosides (tobramycin, gentamycin, amikacin, etc.)
- MRI/CT contrast agents
Which anti-fungal medication is given only in life threatening situations
Amphotericin B
Why do Azoles have more SE than terbinifine ?
Azoles bind ergosterol which is similar in structure to cholesterol
Inhibits CYP450
Eukaryotic cell is similar to the human cell (cholesterol and CYP450)
Examples Yeast Infections
Candidia
Dermatophyte (Tinea = ring worm)
Different locations of Tinea infections
Tinea corpus (body)
Tinea capitus (hair/scalp)
Tinea onychomycosis (nails)
Tinea pedis (foot)
Tinea Versicolour (body)
Tinea Cruris (Jock)
Terbinafine mechanism of action
Inhibits squaline epoxide
accumulation of squaline in the fungal cells results in cell death
*less SE
Terbinafine SE
Hepatotoxicity
HA, N/V, GI upset, Rash
Sensory disturbances - smell, taste, hearing
Which Tinea infections require systemic vs. topical treatments
Tinea capitus (scalp)
Tinea Onychomycoses (nails)
Treatment:
Oral terbinafine
Oral griseofulvin
Griseofulvin mechanism of action
deposits in kerokinocytes of hair and nails
inhibits microtubules and mitosis
hair and nails grows in resistant to fungus
Nystatin mechanism of action
Polyene anti-fungal
Binds to ergosterol and disrupts fungal cell membrane
*Not absorbed systemically
