Antifungals Flashcards
Is griseofulvin fungistatic or fungicidal?
Fungistatic
What are the contraindications to griseofulvin?
Hypersensitivity
Pregnancy (Cat D) / lactation
- Males can’t father children 6 months
Severe liver disease
Photosensitivity disorders e.g. SLE
How is griseofulvin dosed in adults and children?
What dosing instructions should be given?
Adults: 500mg-1g daily (pedis, nails)
Children: 20mg/kg/daily (max 1g daily)
Take after meal with milk
What drug interactions occur with griseofulvin?
Antacids/H2 antagonists (reduced absorption)
Alcohol (disulfuram like reaction)
Griseofulvin reduces concentration of OCP & Warfarin (CYP450 enzyme inducer)
What are the adverse effects of griseofulvin?
Common: GI effects, dysguesia, headache, photosensitivity, menstrual irregularities, liver disturbance, blurred vision, teratogenicity
Serious: TEN, SLE, leukopenia, serum sickness-like reaction
What is the MOA of griseofulvin?
Disrupts fungal cell microtubule function
What are the contraindications to terbinafine?
Hypersensitivity
Lactation
Severe liver disease
Psoriasis
Lupus erythematous
Renal insufficiency (CrCl <50) —> 125mg daily
How is terbinafine metabolised and what drugs interact with it?
CYP2D6
SSRI, MAOi, TCA, antipsychotics, doxepin
What are the side effects of terbinafine?
Common:
GI effects
Headache, dizziness, arthralgia, fatigue
Skin rash, pruritus
Dysgeusia
Deranged LFTs
Rare/serious: lupus erythematosus, photosensitivity, psoriasis, SJS/TEN, alopecia, pancreatitis, liver failure, cytopaenias
What is the pregnancy category,
And can Terbinafine be used in pregnancy and/or lactation?
Category B1
Pregnancy - Yes
Lactation - No
What is the weight-based dosing of terbinafine in children?
> 40kg 250mg daily
20-40kg 125mg daily
10-20kg 62.5mg daily
What is the MOA of fluconazole?
Blocks synthesis of ergosterol (component of the fungal cell wall)
What are the contraindications to fluconazole?
Hypersensitivity
Pregnancy/lactation
Severe hepatic or renal disease
Cardiac disease
- heart failure
- QT prolongation
- dysthymias
What are the adverse effects of fluconazole?
GI effects, headache
Hepatotoxicity
QT prolongation
SCAR
Anaphylaxis
How is fluconazole dosed in
a. Onychomycosis
b. Tinea
c. Pityriasis versicolor
d. Candidiasis
a. 150mg weekly (6-9 months fingernails and 12-18 months toenails)
b/c. 150mg weekly or 50mg daily for 2-6 weeks
D. 150mg stat, can repeat 3 days later
What is the MOA of itraconazole?
Blocks ergosterol synthesis
Fungistatic
What are the contraindications to itraconazole?
Hypersensitivity
Pregnancy
Severe liver disease
Cardiac
- congestive heart failure
- QT prolongation
- dysrhythmias
What are the drug interactions for itraconazole?
CYP3A4 substrates/inducers/inhibitors
Drugs that
- prolong QT
- anti-arrythmics
- reduce cardiac output/heart rate
What are the adverse effects of itraconazole?
Common: GI effects, headache, URTI sx, transaminitis, hyperlipid/triglyceridemia
Rare/serious:
Skin: EM/SJS/TEN, leukocytoclastic vasculitis, urticaria/angiooedema
CNS: insomnia, somnolence, peripheral neuropathy
Endo: gynaecomastia, impotence
CVS: hypertension, CCF, APO
GI: hepatitis, pancreatitis
Haem: cytopaenias
How is itraconazole dosed?
a. Fungal nail infection
b. Tinea corporis
c. Pityriasis versicolor
d. VV candidiasis
a.
Regular: 200mg daily 3 months
Pulse: 200mg twice daily for 1 week per month for 2-4 months
b. 200mg twice daily for 1 week
c. 200mg daily for 1 week
d. 200mg daily for 3 days
What baseline and ongoing monitoring is required for itraconazole?
Baseline: LFTs
Follow-up: LFTs every 4-6 weeks
