Microbiology: TOENAIL funk: Tinea Unguium
--Tinea Unguium = a subset of onychomycosis, which includes dermatophyte, nondermatophyte and yeast infections of the nails
--toenails are involved more frequently than fingernails
--usually not curable in the toenails according to http://apma-nc.com/PatientEducation/tinea_unguium.htm
--affects adults more often than children*
--*seems to be occurring more in kids I'd guess along with syndrome x, this article about underdiagnosis by pediatricians: http://www.news-medical.net/?id=32645
--toenail infx extremely resistant infection with a tendency to recur
--infection involves one or more (but usually not all) nails
--infected fingernails can usually be successfully treated, but toenails are more difficult
--clinical presentation depends on invasion: distal, proximal or superficial nail
--distal = most common
--affected nail is hyperkeratotic, chalky and dull
--nails are thick and brittle, yellow
--brownish-yellow debris forms beneath the nail and nail separates from its bed
--nail plate may become brittle, but the nail fold is seldom involved
--inflammation uncommon
--co-infx with tinea manuum or tinea pedis is common
PREVENTION
--Keep dry
--dry well after bath/shower
--wear loose clothing, shoes
--change sox often
--wear open toed shoes
--use talc
--don't eat sugar
--don't go to Brasil: Trichophyton raubitschekii: A new agent of dermatophytosis? http://dermatology.cdlib.org/91/case_reports/tinea/costa.html
RISK FACTORS:
--being a raft guide
--increasing age
--poor venous and lymphatic drainage
--ill-fitting shoes
--sports participation
--using steroid creams or steroid pills
--diabetes
--high blood sugar
--tinea pedis (athlete's foot)
--disease of the small blood vessels (peripheral vascular disease)
--older women (perhaps because estrogen deficiency increases the risk of infection)
--wearing artificial nails (acrylic or "wraps")
--infx often recur after Tx
TREATMENTS
--feet in the ocean every day for a year, barefoot on the beach
--topical corticosteroids oft used as adjuncts to antifungal pills, not used alone
--long term treatments needed
--BEWARE of drug interactions!!
--most fungal drugs are HARD ON THE LIVER
--removal of infected nail and topical antifungal as new nail grows in
--live with it
--for mild cases, fingernails mainly: gel (Naftifine) or a lotion (Ciclopirox) may work after 4 to 6 months but usu need orals too
--once treated fingernail infections often do not come back.
--Many oral antifungal agents interact with other medications
--top 2 oral TX: Itraconazole, terbinafine
--When itraconazole or terbinafine is used in the treatment of tinea unguium, the nail may not appear clinically cured at the end of therapy, must wait for new nail to grow out, 4-6 months or longer.
--topical antifungal agents--therapeutic success is limited because of the lengthy duration of treatment, poor patient compliance and high relapse rates at specific body sites
--Absorption properties of oral antifungal agents vary, may need fat or good HCl for absorbtion
ITRACONAZOLE
--itraconazole "pulse" therapy (i.e., a series of brief medication courses) is FDA approved for the treatment of tinea unguium of the fingernails
--total drug exposure is less with pulse therapy, cost is also lower than traditional treatment, patients may be more likely to comply with therapy due to drug-free intervals
--pulse therapy not FDA approved for toenails
-- 200 mg a day for 3 months or 400 mg a day for the first week of each month for 3 months.
--itraconazole is better tolerated than griseofulvin
----most common complaints with itraconazole are headache and gastrointestinal distress
----Reversible elevations in liver enzyme levels occur in 0.9 percent of patients treated with itraconazole
----more serious, rare: hepatotoxicity, hallucinations, hypokalemia, edema
--Itraconazole and ketoconazole rely on gastric acidity for optimal absorption
--drinking cola acidifies stomach & increases absorbtion up to 60%
----Itraconazole, fluconazole and ketoconazole significantly inhibit P450's, particularly subgroup 3A4
TERBAFINE
--Terbinafine pulse therapy: insufficient data?
-- 250 mg a day for 3 months is usually the treatment of choice.
--absorption of terbinafine and fluconazole is not influenced by gastric pH
----Terbinafine has fewer drug interactions because it minimally affects the cytochrome P450 enzyme system.
FLUCONAZOLE, GRISEOFULVIN
--fluconazole: insufficient data?
--Griseofulvin and Fluconazole are not very good choices for toenail infections.
--griseofulvin should be taken with a fatty meal
--Ultramicrosize griseofulvin was designed to decrease the need to be taken with food
--absorption of terbinafine and fluconazole is not influenced by gastric pH
----Itraconazole, fluconazole and ketoconazole significantly inhibit P450's, particularly subgroup 3A4
--griseofulvin causes side effects in 20 percent of patients
----headache or gastrointestinal complaints
----rare and more serious adverse reactions: toxic epidermal necrolysis and photodermatitis myositis
KETOCONAZOLE
--THIS IS WHAT I TOOK
--reserved for second-line treatment of recalcitrant superficial fungal infections
----HIGHEST risk for hepatotoxicity
----reported incidence ranging from one case per 10,00039 to one case per 70,00041 recipients
----pts must immediately report symptoms of hepatotoxicity such as anorexia, nausea and vomiting. H
----Risk factors w/ ketoconazole-induced hepatotoxicity: female gender, onychomycosis, alcoholism, ketoconazole therapy lasting more than two weeks and previous griseofulvin treatment.
----Ketoconazole therapy should be discontinued if symptomatic liver inflammation occurs or if the results of liver function tests are three times higher than normal.
----Liver enzyme levels usually return to normal after ketoconazole is discontinued.
--Ketoconazole is also associated with asymptomatic increases in transaminase levels in 5 to 10 percent of patients. More common side effects include gastrointestinal complaints and pruritus.
--side effects of fluconazole are rash, headache, gastrointestinal disorders and elevated liver function levels. Rare: erythema multiforme
--Skin rashes and gastrointestinal side effects common with terbinafine. Also been associated with Stevens-Johnson syndrome, blood dyscrasias, hepatotoxicity and ocular disturbances, as well as elevated liver enzymes, losing sense of taste for up to six weeks!!
--Itraconazole and ketoconazole rely on gastric acidity for optimal absorption
GOOD TINEA OVERVIEW:
http://www.aafp.org/afp/980700ap/noble.html