Antifungal Dosing for Tinea Infections

Dermatophyte (tinea) infections

§  Dermatophytes are filamentous fungi in the genera Trichophyton, Microsporum, and Epidermophyton.

§  Dermatophytes metabolize and subsist upon keratin in the skin, hair, and nails.

§  The major clinical subtypes of dermatophyte infections are:

	Location	Griseofulvin (microsize)	Fluconazole	Itraconazole
Tinea corporis	Body surfaces other than the feet, groin, face, scalp hair, or beard hair	500 mg OD-BD for 2-4 weeks1 or 4-6 weeks2	150-200 mg once weekly for 2-4 weeks3	200 mg OD for 1 week1 or 2 weeks2
Tinea cruris (jock itch)	Groin	500 mg OD-BD for 2-4 weeks1 or 4-6 weeks2	150-200 mg once weekly for 2-4 weeks3	200 mg OD for 1 week1 or 2 weeks2
Tinea pedis	Foot	500 mg BD for 4-8 weeks1 or 6-12 weeks2	150 mg once weekly for 2-6 weeks3	200 mg BD for 1 week1 or 200 mg OD for 2-4 weeks2
Tinea capitis	Scalp hair	(First line) 500 mg OD-BD for 4-6 weeks1 or 6-12 weeks2 or longer until fungal cultures are negative2	6 mg/kg/day (max. 400 mg/day) for 3-6 week 1 Or 8 mg/kg once weekly (max. 150 mg/week) for 8-12 weeks 4	200 mg OD for: 2 ·      Trichophyton: 2-4 weeks ·      Microsporum: 8-12 weeks Or 5 mg/kg/day (max. 400 mg/day) for 4-6 weeks 1
Tinea unguium (derma-tophyte onycho-mycosis) – Pulsed Therapy	Nail	-	150 mg2-300mg1,4 once weekly * Fingernail: 3-6 months 1,2,4 * Toenail: 6-12 months 1,2,4	(First line) 200 mg BD for 1 week per month 1,2 * Fingernail: 2 months * Toenail: 3 months
Tinea unguium (derma-tophyte onycho-mycosis) – Continuous Therapy	Nail	500 mg BD for 4-6 month or longer 2 * Fingernail: 6 months * Toenail: 12 months	-	(First line) 200 mg/day for:1 * Fingernail: 6 weeks * Toenail: 12 weeks

§  Based on NAG 2014: Treatment for tinea barbae (hair) is the same as tinea capitis.

§  Nystatin, an effective treatment for Candida infections, is NOT effective for dermatophytes.

§  Extra notes on griseofulvin:

o  Administer with a fatty meal to increase absorption

o  Laboratory evaluation prior to griseofulvin treatment is not necessary. However, if therapy is continued beyond eight weeks or repeated courses of griseofulvin are given, liver function tests and a complete blood count should be obtained to evaluate for hepatic or hematologic toxicity.

o  Teratogenic effects have been observed in animal reproduction studies. Griseofulvin crosses the placenta. Because adverse events have also been observed in humans (two cases of conjoined twins), use during pregnancy is contraindicated. Effective contraception should be used during therapy and for 1 month after therapy is discontinued in women of reproductive potential. Men should avoid fathering a child for at least 6 months after therapy.

Tinea versicolor

·      Tinea versicolor (ie, pityriasis versicolor) is a common superficial fungal infection. Patients with this disorder often present with hypopigmented, hyperpigmented, or erythematous macules on the trunk and proximal upper extremities.

·      Unlike other disorders utilizing the term tinea (eg, tinea pedis, tinea capitis), tinea versicolor is not a dermatophyte infection.

·      The causative organisms are saprophytic, lipid-dependent yeasts in the genus Malassezia (formerly known as Pityrosporum).

	Location	Griseofulvin (microsize)	Fluconazole	Itraconazole
Tinea versicolor	skin	NOT effective	If topical therapy failed: 300 mg once weekly for 2 week2 Or 400mg STAT 2	If topical therapy failed: 200 mg OD for 5-7 days2 Or 200 mg OD for 7 days (recurrent cases)2 Or 400mg STAT 2,4

References:

1. UptoDate on Tinea topics [Accessed on 28 Nov 2018]
2. National Antibiotic Guideline 2014
3. UptoDate: Fluconazole: Drug information [Accessed on 28 Nov 2018]
4. Sanford Guide to Antimicrobial Therapy [Apps: Last Updated on 24 Nov 2018]

Acyclovir Dose for Varicella Pneumonia in Immunocompromised Patients

Reference	Dosage Suggested / Utilised
Human Herpesviruses: Biology, Therapy, and Immunoprophylaxis. Chapter 65 : Antiviral therapy of varicella-zoster virus infections (by John W. Gnann Jr.)	10–15 mg/kg (or 500 mg /m2) intravenously every 8 h for ≥7 d
Viral Pneumonia Treatment & Management [Medscape]	10 mg/kg IV q8h for 7 d
Uptodate : Treatment of varicella (chickenpox) infection	10 mg/kg IV every 8 hours (using ideal body weight [IBW] if obese)
Uptodate : Acyclovir (systemic): Drug information	IV: 10 to 15 mg/kg/dose every 8 hours for 7 to 10 days; may switch to oral antiviral after defervescence if no evidence of visceral involvement; continue until all lesions are crusted (HHS [OI adult 2018]; Pergam 2013)
Varicella Pneumonia in Adults (by Abba A.A. 2005)	10 mg/kg q8h for 7,10 days
Caso Clínico: Pneumonia a Varicella zoster (by Gomes et al. 2010)	5-15 mg/kg q8h for 7-10 days
Sanford Guide to Antimicrobial Therapy (Apps: Last Updated on 24 Nov 2018)	Serious HSV/VZV infections: 5-12.5 mg/kg IV q8h
BNF 76 (2018-19)	Varicella zoster (chickenpox), treatment in immunocompromised | Herpes zoster (shingles), treatment in immunocompromised IV 10 mg/kg every 8 hours, usually for 5 days
Varicella-zoster virus pneumonia in adults: report of 14 cases and review of the literature Christos Y. Frangidesa, Ioannis Pneumatikos [European Journal of Internal Medicine 2004]	All patients were treated immediately after the diagnosis of VZVP with intravenous acyclovir in a dose of 10 mg/kg every 8 h (600–900 mg intravenously, three times a day). The mean duration of acyclovir therapy initiation after the appearance of varicella rash was 3 days (range of 1–5 days). The mean duration of acyclovir therapy was 16±6 days.

All accessed online on 28/11/18