DERM 14: Onychomycosis Flashcards
1
Q
What is the etiology of onychomycosis? (3)
A
dermatophytes
- majority of fungal toenail infections – tinea unguium
- trichophyton rubrum
non-dermatophyte molds (NDM)
- acremonium sp.
- aspergillus sp.
- fusarium sp.
yeasts
- majority of fingernail infections
- candida albicans
2
Q
How is onychomycosis transmitted? (2)
A
- direct contact with infected persons, infected pets, soil or plant material
- indirect contact with fomites
3
Q
What are the risk factors for onychomycosis?
A
- increasing age (> age 40)
- male
- trauma to nails
- history of tinea pedis
- occlusive footwear
- concurrent medical conditions (diabetes, immunocompromised, psoriasis, peripheral vascular disease)
- participation in sports (tennis, swimming)
- walking barefoot
- family history or genetics
- infected family members
4
Q
What is distal lateral subungual onychomycosis (DLSO)?
A
- most common type
- fungus invades from distal part of nail
- first and/or fifth toenails most common
- pharmacists can prescribe
5
Q
What are the signs and symptoms of distal lateral subungual onychomycosis (DLSO)?
A
- nail thickening
- whitish/yellow, black/brown discolouration
- crumbling
- subungual debris
- dermatophytomas (streaks)
- onycholysis can occur
- pain or discomfort
6
Q
What is superficial white onychomycosis (SWO)?
A
- more common in children than adults
- fungus invades upper surface of nail plate
7
Q
What are the signs and symptoms of superficial white onychomycosis (SWO)?
A
- superficial, chalky white patches
- soft, crumbly
8
Q
What is proximal subungual onychomycosis (PSO)?
A
- can be more common in immunosuppressed or repeated nail trauma
- fungus invades from under proximal nail fold and spreads distally
9
Q
What are the signs and symptoms of proximal subungual onychomycosis (PSO)?
A
white discolouration or diffuse white patches
10
Q
How is onychomycosis diagnosed?
A
- clinical
- recommend microscopy (KOH preparation) +/- culture to confirm before treatment – many similar nail conditions, and long treatment duration
11
Q
What are the differential diagnoses?
A
- superficial white onychomycosis (SWO)
- proximal subungual onychomycosis (PSO)
- eczema
- bacterial paronychia
- contact dermatitis
- drug-induced nail disorders
- lichen planus
- onychogryphosis (senile)
- psoriasis
- squamous cell cancer
- subungual melanoma
- systemic disorders
- trauma to nails
- yellow nail syndrome
12
Q
When should patients be referred? (4)
A
- < 18 years old – uncommon for DLSO
- unclear diagnosis – nails have features of other nail disorders
- more severe presentation requiring systemic therapy – several nails affected, most of nail infected
- no improvement after topical treatment or new lesions appear during treatment
13
Q
Who should be treated for onychomycosis?
A
- ↑ risk of secondary bacterial infections – history of lower leg cellulitis, diabetes, immunosuppressed
- experiencing pain or discomfort because of infected nails
- desire treatment due to cosmetic reasons
14
Q
What are the goals of therapy? (5)
A
- improve appearance of nail
- eradication of organism
- prevent complications – cellulitis or foot ulcers, difficulty walking or wearing footwear, nail deformities, social/psychological effects
- prevent spread of organism
- reduce rate of recurrence
15
Q
What is mycological cure?
A
eradication of organism determined by potassium hydroxide (KOH) test and culture
16
Q
What is clinical cure?
A
- complete clinical cure = 0% nail plate involvement
- clinical improvement = < 5-10% nail plate involvement
- incomplete clinical response = > 10% nail plate involvement (reassessment is required)
17
Q
What is complete cure?
A
mycological + clinical cure
18
Q
What are the treatment options for tinea unguium (onychomycosis)? (5)
A
- topical therapy
- oral therapy
- mechanical nail avulsion
- chemical avulsion
- combination of the options
19
Q
What are the topical therapy options? (3)
A
- propylene glycol-urea-lactic acid (Emtrix)
- efinaconazole (Jublia)
- ciclopirox (Penlac)
20
Q
What are the advantages of topical therapy? (3)
A
- apply directly to site of action
- minimal systemic absorption – less side effects, drug-drug interactions
- likely more effective when treating early
21
Q
What are the disadvantages of topical therapy? (5)
A
- long treatment duration
- lower efficacy rates compared to oral
- may not penetrate nail plate adequately
- need adequate dexterity to apply
- high cost
22
Q
Propylene Glycol-Urea-Lactic Acid (Emtrix)
What is it used for?
A
mild DLSO
- OTC product
23
Q
Propylene Glycol-Urea-Lactic Acid (Emtrix)
How is it administered?
A
apply to affected nail and under free edge once daily
24
Q
Propylene Glycol-Urea-Lactic Acid (Emtrix)
What are the side effects?
A
- irritation of skin next to infected nail (transient)
- whitening of nail
25
Efinaconazole 10% Solution (Jublia)
What is it used for?
mild to moderate toenail DLSO (≤ 50%)
- prescription (MACS)
26
Efinaconazole 10% Solution (Jublia)
What drug class is it?
triazole antifungal
- active against dermatophytes, candida, moulds
27
Efinaconazole 10% Solution (Jublia)
How is it administered?
apply 1 drop (or 2 if great toenail) daily x 48 weeks to entire nail, nail folds, surrounding skin, nail bed, hyponychium, under nail edge
28
Efinaconazole 10% Solution (Jublia)
What are the side effects?
- vesicles at application site
- dermatitis
29
Ciclopirox 8% Solution (Penlac)
What is it used for?
mild to moderate fingernail/toenail DLSO
- prescription lacquer
30
Ciclopirox 8% Solution (Penlac)
What drug class is it?
pyridone antifungal
- broad spectrum (dermatophytes, candida, some moulds)
31
Ciclopirox 8% Solution (Penlac)
How is it administered?
- once daily (preferably HS) x 48 weeks to affected nail, nail bed, undersurface of nail plate, surrounding skin
- weekly clipping and monthly debridement (in office) recommended alongside therapy
32
Ciclopirox 8% Solution (Penlac)
What are the side effects?
- periungual erythema
- erythema of proximal nail fold
- contact dermatitis
33
What are the oral therapy options? (3)
- terbinafine – drug of choice
- itraconazole
- fluconazole
34
What are oral therapy options used for?
any disease
- mild to moderate disease
- severe disease – treatment of choice
35
What are the advantages of oral therapy compared to topical? (4)
- higher efficacy rates – ↑ penetration to nails
- shorter treatment course
- more cost effective
- can be used for more severe cases of OM
36
What are the disadvantages of oral therapy? (2)
- systemic absorption increases risk for side effects and drug-drug interactions
- may require lab monitoring
37
Terbinafine
What drug class is it?
allylamine antifungal
- dermatophytes, some NDM and candida
- fungicidal
38
Terbinafine
What is the dose?
250 mg PO daily
- fingernails: 6 weeks
- toenails: 12 weeks
39
Terbinafine
What are the drug-drug interactions?
inhibits CYP2D6 enzymes
40
Terbinafine
What are the side effects?
- headache, GI, ↑ LFTs
- rare: hepatotoxicity, SJS
41
Itraconazole
What drug class is it?
azole antifungal
- broad spectrum against dermatophytes, NDM and candida
- fungistatic
42
Itraconazole
What is the dose?
pulse:
- 200 mg PO BID x 1 week/month
- fingernails: 2 months
- toenails: 3 months
continuous: 200 mg PO daily
- fingernails: 6 weeks
- toenails: 12 weeks
give with food to increase absorption
43
Itraconazole
What are the drug-drug interactions?
potent CYP3A4 inhibitor
44
Itraconazole
What are the side effects?
- GI (nausea), rash, ↑ LFTs
- rare: hepatotoxicity, SJS
45
Fluconazole
What is the drug class?
azole antifungal
- dermatophytes, candida, some NDM
46
Fluconazole
What is the dose?
150 mg PO once weekly
- fingernails: 3 months
- toenails: 6-9 months
- longer treatment course – shorter residual concentration in nails
47
Fluconazole
What are the drug-drug interactions?
inhibits CYP2C9, CYP2C19, CYP3A4
48
Fluconazole
What are the side effects?
- headache, GI upset, rash, ↑ LFTs
- rare: hepatotoxicity, SJS
49
What are the monitoring points for efficacy?
- measure distance of outgrowth of disease-free nail (normal growth rate is 1.5-2 mm/month)
- cessation of growth of diseased nail (6 weeks for fingernails, 12 weeks for toenails)
- normal appearance of nail (at 12 months or longer)
- resolution of discomfort or pain
- absence of secondary bacterial or fungal infections
50
What are the monitoring points for safety?
- adverse drug reactions of topical or oral therapy
