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Wednesday, September 2, 2015

Treatment of Onychomycosis

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  • suggest initial treatment of dermatophyte onychomycosis with oral terbinafine (not available in HKGU) since data suggest it has greater efficacy than the alternatives and fewer serious side effects. 
  • Other options may be preferable in some patients, however, based on local costs of therapy or the desire to treat with pulse therapy in patients who wish to limit the total intake of pills. 
  • Oral itraconazole appears to be a more effective initial agent for treatment of nondermatophyte mold onychomycosis and yeast onychomycosis. It is used in the same dose regimens as that used for dermatophyte onychomycosis.

Drugs
Adult
Children
·  Comments
Itraconazole (A*)

-Fixed dosage1
·    For fingernails – 200 mg daily by mouth for six weeks
·    For toenails – 200 mg daily by mouth for 12 weeks

-Pulse therapy1
·    For fingernails – 200 mg twice daily by mouth for one week per month for two months
·    For toenails – 200 mg twice daily by mouth for one week per month for three months

-Daily for one week per month (two months therapy for fingernails; three months therapy for toenails)1:
Less than 20 kg: 5 mg/kg daily
20 to 40 kg: 100 mg daily
40 to 50 kg: 200 mg daily
More than 50 kg: 200 mg twice daily
                   OR
·  Child1-12 yrs: 5 mg/kg (max 200 mg) daily for 7 days; subsequent courses repeated after 21 days interval; fingernails 2 courses; toenails 3 courses.3
·  Child 12-18 yrs: either 200 mg OD for 3 months or 200 mg BD for 7 days, subsequent course repeated after 21 days intervals; fingernails 2 courses, toenails 3 courses.3
·  common SE headache and gastrointestinal upset
·  Adverse effects are lower if itraconazole is given as pulse therapy
·  Asymptomatic liver function abnormalities
·  Hepatitis tends to occur with continuous therapy usually after 4 weeks
·  Monitor for therapy more than 1 month
·  contraindicated in patients with congestive cardiac failure

Fluconazole (A)

·  For fingernails- 150 mg PO once weekly for 3-6 months4
·  For toenail- 150-300 mg PO once weekly for 6-12 months4
·   3 to 6 mg/kg one dose per week (12 to 16 weeks for fingernails; 18 to 26 weeks for toenails)1
·  currently not licensed for use in onychomycosis
·  Clinical cure rates were lower (28–36% for toenail infections and 76–90% for fingernail infections)
·  Common SE include headache, skin rash, gastrointestinal complaints and insomnia
Griseofulvin
(B)

·  Microsize- 1000 mg daily in single or divided doses2. Duration: 4-6 months or longer2

Oral: Children >2 years2:
·   Microsize: 10-20 mg/kg/day in single or 2 divided doses (maximum: 1000 mg daily). Duration: 4-6 months or longer2
·  Mycological cure rates for toenail infection are only 30–40%
·  SE include nausea and rashes in 8–15% of patients
·  contraindicated in pregnancy and caution against men fathering a child for 6 months after therapy
·  llimitations including lower efficacy, long treatment duration, risk of greater drug interactions and the availability of newer antifungal agents

·  Not available in HKGU
Terbinafine
·    For fingernails – 250 mg daily by mouth for six weeks 1
·    For toenails – 250 mg daily by mouth for 12 weeks1

-Six weeks for fingernails; 12 weeks for toenails1:
10 to 20 kg: 62.5 mg daily
20 to 40 kg: 125 mg daily
Above 40 kg: 250 mg daily
·  most common SE were gastrointestinal (49%), such as nausea, diarrhoea or taste disturbance, and dermatological events (23%) such as rash, pruritus, urticaria or eczema
·  LFT recommended in patients with history of heavy alcohol consumption, hepatitis or haematological abnormalities
Amorolfine 5 % Lacquer
·  Apply once-twice weekly until nail is regenerated and areas are cured.4
·  Apply to the infected nail 1-2 times weekly after filling and cleansing; allow to dry; treat finger nails for 6 months and toe nails for 9-12 months.3
·  effective in around 50% of cases of distal fingernail and toenail onychomycosis
·  SE are rare and are limited to local burning, pruritus and erythema
References:
  1. Onychomycosis. Adam O Goldstein, MD, MPH. Uptodate 2014. 
  2. Lexicomp
  3. BNF For Children 2013-2014
  4. Tinea Unguimn. MIMS GATEWAY Disease Chart.
  5. British Association of Dermatologists’ guidelines for the management of onychomycosis 2014

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