Isotretinoin

• Topical: in acne papulopustulosa.
• Systemic: most severe forms of acne papulopustulosa, acne conglobata, acne tetrade. In rosacea, the use of low-dose therapy should be considered.

Initially 0.5 mg/kg bw/day p.o. for 4 weeks, then with good results the same dose for 2-3 months. If the effect is insufficient, increase the dose up to 1 mg/kg bw/day. Dosages of more than 40 mg/day should be divided into two single doses. If the initial dose is low, the success of the therapy takes longer. With extensive clinical improvement gradually (0.1 mg/kg bw every 4 weeks) reduction to a maintenance dose (0.05-0.1 mg/kg bw/day). For the maintenance dose of 0.05 mg/kg bw/day good healing rates are documented. Here, the NW profile is clearly reduced.

The recommended duration of therapy is 15-20 weeks. Experience has shown that in some patients only longer treatment periods, up to 32 weeks, guarantee complete healing. The total dose should be above 120 mg/kg bw.

As a "low-dose" application, good experience with rosacea has been reported (initial: 10 mg/day p.o.; maintenance dose 10 mg every 2nd day).

Topical: Erythema, lightening of skin and hair, skin irritation, skin dehydration, skin flaking, skin atrophy, photosensitization, pruritus, rhagades. Rare hyperhidrosis.

Systemic: see the general side effects of retinoids; see under retinoids.

The most frequent side effects are dryness of the lips and nasal mucous membranes.

• In combination with keratolytics there is an increased skin irritation; interactions in case of systemic application. S.a.u. retinoids.
• The (active) metabolite of isotretinoin is tretinoin, which is unstable against light and oxygen (benzoyl peroxide therapy!).

Pregnancy, lactation, use on eyes and mucous membranes, acute dermatitis or eczema, intensive sun exposure; systemic, see retinoids below.

Children: Isotretinoin is not indicated for the treatment of prepubertal acne and is not recommended for patients under 12 years of age.

Systemic: acne normine, isoderm, isopel.

Topical: Isotrex; isotrexine (combination with erythromycin).

• Treatment of women of childbearing age is the responsibility of the prescribing doctor and should only be carried out if there is sufficient compliance. The patient must be informed in detail about the teratogenic risks of the substance before starting treatment and must confirm this in writing! A negative pregnancy test must be available before therapy and adequate contraceptive protection must be in place during therapy, whereby the effect of oral contraceptives may be impaired!
• The capsule material of isotretinoin contains peanut components! This medication is contraindicated in the case of a peanut allergy. Alternatively, acitretin (0.3 mg/kg bw/day) can be used for acne vulgaris (peanut-free).
• The connection between acne therapy with isotretinoin and the risk of developing depression is controversially discussed. This question was investigated in a meta-analysis (Huang et al. 2017). There was no evidence of an increased risk of developing depression, but rather the opposite.

1. Huang YC et al (2017) Isotretinoin treatment for acne and risk of depression: A systematic review andmeta-analysis. J Am Acad Dermatol 76:1068-1076.