tinea%20unguium
TINEA UNGUIUM
Onychomycosis is a fungal infection of the nail bed, nail plate or both. It is caused by dermatophytes, non-dermatophyte molds and yeast.
Tinea unguium or dermatophytic onychomycosis is a dermatophyte infection of the nail more commonly affecting the toenails than the fingernails.
It is usually asymptomatic and patients first consult for cosmetic reasons.
It is suspected if there are changes in the 3rd or 5th toenail, involvement of the 1st and 5th toenails on the same foot and unilateral nail changes.

Principles of Therapy

  • Treatment for onychomycosis is indicated when:
    • Patients experience pain or discomfort related to the infected nails
    • Patients have diabetes & other risk factors for cellulitis
    • Patients have a history of ipsilateral lower extremity cellulitis
    • For cosmetic reasons
  • Patients w/ confirmed onychomycosis but are refractory to treatment may benefit from switching to an alternative oral agent

Pharmacotherapy

Oral Antifungals

Fluconazole

  • Active against common dermatophytes, Candida sp & some non-dermatophytic molds
    • Offers an alternative to Itraconazole & Terbinafine
    • Not approved in most countries for onychomycosis treatment
  • Effects: Fungistatic, high-dose pulse therapy for fingernail treatment has been shown to have up to 90% clinical cure rate w/ near-total mycologic elimination
    • Outcome data on toenail treatment shows clinical improvement in 72-89% of patients treated

Itraconazole

  • Has broad antifungal coverage that includes dermatophytes, Candida sp & a number of non-dermatophyte molds
  • Effects: Fungistatic, mycologic cure rates range from 45-70% & clinical cure rates from 35-80%
    • Studies have shown that both continuous & pulse therapies are effective

Terbinafine

  • Active against dermatophytes which are the cause of the majority of onychomycosis infections
    • Not as active against Candida sp or non-dermatophyte molds
  • Effects: Fungicidal, mycotic cure rate for toenails is 71-82% & clinical cure rate 60-70%
    • Some comparative trials have shown Terbinafine to be more effective than other agents for onychomycosis treatment

Topical Antifungals

  • Limited to mild cases involving very distal nail plate & in those unable to tolerate systemic treatment
    • Low response rate because of poor nail plate penetration
  • Used as an adjunct to oral therapy for resistant infections
  • May combine w/ surgical nail avulsion

Amorolfine

  • Active against dermatophytes, dimorphic fungi, yeasts, other filamentous & dematiaceous fungi
  • Effects: May be effective in patients w/ mild infection w/o nail matrix (lunula) involvement
  • Has been used in combination w/ oral Terbinafine or Itraconazole
    • Combination therapy may be useful for patients w/ severe onychomycosis

Ciclopirox

  • Indicated in mild-to-moderate distal superficial onychomycosis
  • Treatment may take 6 months-1 year & cure rates range from 29-47%

Efinaconazole

  • A triazole antifungal, developed for the treatment of mild-to-moderate distal & lateral subungual onychomycosis (DLSO)
  • Inhibits fungal lanosterol 14α-demethylase, involved in the biosynthesis of ergosterol
  • Indicated for onychomycosis of the toenails due to Trichophyton rubrum or Trichophyton mentagrophytes

Luliconazole

  • An imidazole molecule w/ fungicidal & fungistatic activity
  • Used as treatment for moderate-to-severe DLSO

Tavaborole

  • A light-weight, water-soluble oxaborole topical nail lacquer (boron-containing-compound)
  • Indicated for onychomycosis of the toenails due to Trichophyton rubrum or Trichophyton mentagrophytes

Longer courses of antifungals may be needed in:

  • Patients whose nails grow slowly
  • Patients who have decreased blood supply to the nail as a result of conditions (eg peripheral vascular occlusion or DM)
  • Patients who have near-total or total nail plate involvement
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