Isotretinoin
Vitamin A Derivative for Severe Acne: Effects, Use and Important Notes
Isotretinoin is a retinoid, a derivative of vitamin A, used in dermatology for severe acne. The compound is considered one of the most effective available treatment approaches for nodular-cystic or therapy-resistant acne. It acts simultaneously on several mechanisms involved in acne formation. Complete or near-complete remission of acne is possible in a relevant proportion of patients after a treatment course.
Important note on teratogenicity: Isotretinoin has a high teratogenic potential. This means it can cause serious malformations in the unborn child if taken during pregnancy. Pregnant women must not take isotretinoin. Women of childbearing age must use reliable contraception during treatment and for a defined period thereafter. This is governed by a strict pregnancy prevention programme, which forms part of every treatment course and is documented by the treating physician.
Mechanism of Action
Isotretinoin exerts its effects through several mechanisms that together contribute to the reduction of acne lesions:
Inhibition of Sebaceous Gland Activity
The most important mechanism of isotretinoin is a pronounced reduction in sebum production. Sebaceous glands play a central role in acne formation: excess sebum blocks hair follicles and creates an environment in which acne bacteria (Cutibacterium acnes) can thrive. Isotretinoin markedly reduces the size and activity of sebaceous glands, leading to a sustained decrease in sebum production. This effect persists in many patients even after completion of therapy.
Normalisation of Keratinisation
A further mechanism relates to the keratinisation of follicular walls. In acne, abnormal keratinisation contributes to pore blockage and comedo formation. Isotretinoin normalises this process and thereby prevents the formation of new blackheads and comedones. Follicular hyperkeratosis, a fundamental step in acne formation, is thereby inhibited.
Anti-inflammatory Effect and Bacterial Reduction
The reduced sebum production worsens the growth environment for Cutibacterium acnes. In addition, isotretinoin has direct anti-inflammatory activity and reduces inflammatory skin changes. The number of bacteria on the skin decreases markedly in the course of therapy.
Indications
Isotretinoin is approved for the treatment of severe acne, particularly in:
- Nodular-cystic acne with scarring
- Therapy-resistant acne that has not responded adequately to other treatments
- Severe acne with substantial psychosocial burden
- Acne conglobata, a particularly severe form
Therapy is accompanied by dermatologists and requires regular check-ups, including blood tests to monitor blood lipids and liver values, and pregnancy tests for women of childbearing age.
Pregnancy Prevention Programme (Mandatory for Women of Childbearing Age)
Due to the established teratogenicity of isotretinoin, its use in women of childbearing age is subject to a strict risk management programme. The following points are essential:
- Women of childbearing age must provide a negative pregnancy test before starting therapy.
- Reliable contraception must be used throughout the entire treatment period and for at least one month after discontinuation. Two independent methods are recommended.
- Regular pregnancy tests during therapy are mandatory and documented by the physician.
- The compound must not be dispensed to pregnant women.
- Blood donation during and for at least one month after therapy is not permitted.
In men, isotretinoin is considered non-teratogenic via the seminal route based on current knowledge. Nevertheless, all patients should follow their physician's instructions precisely and refrain from self-initiated changes to dosage or treatment duration.
Formulations and Dosage
Isotretinoin is taken orally in the form of soft capsules. Dosage is individually determined by the treating physician, is based on body weight and is adjusted during the course of therapy. A cumulative total dose is an important parameter for therapeutic success and relapse rates after completion of treatment.
Administration is generally daily over several months, typically six to twelve months. Fatty meals can improve absorption of the compound since isotretinoin is fat-soluble. Intake with a fatty meal is therefore advisable.
Adverse Effects
Isotretinoin has a well-known side-effect profile that should be thoroughly discussed with the treating dermatologist:
- Skin dryness, dry lips and mucous membranes are very common and occur in virtually all patients
- Dry eyes and increased photosensitivity of the skin may occur
- Muscle discomfort and joint pain are possible, especially in physically active persons
- Elevated blood lipids (triglycerides, cholesterol) and liver enzymes require regular laboratory monitoring
- Mood changes have been reported; medical help should be sought promptly at any signs of depression or other psychological changes
- Night blindness can occur in rare cases and should be reported to the physician
- Hair loss is possible, usually reversible after completion of therapy
Drug Interactions
Isotretinoin should not be taken simultaneously with vitamin A preparations, as it is itself a vitamin A derivative and overdose can lead to additional adverse effects. Tetracycline antibiotics should not be used concurrently, as the combination increases the risk of elevated intracranial pressure (pseudotumour cerebri). Other retinoids must also not be taken simultaneously.
Skin Care During Therapy
Adapted skin care is important during isotretinoin therapy. Due to skin dryness, dermatologists generally recommend emollient and moisturising products for skin and lips. Aggressive cleansing or exfoliating products should be avoided. High-factor sun protection is especially important during therapy, as the skin may be more sensitive to UV radiation. Waxing and other ablative treatments should be avoided during therapy and for some time thereafter, as the skin is more vulnerable.
Frequently Asked Questions
How long does an isotretinoin treatment course last?
Treatment duration is typically six to twelve months and depends on the cumulative total dose targeted by the treating physician. This cumulative dose is an important factor for the durability of the therapeutic outcome. Overly short treatment courses are associated with a higher relapse rate. In some cases, a second treatment course may be required after an adequate interval.
What happens if acne worsens at the start of therapy?
In some patients, a temporary worsening of acne may occur at the beginning of isotretinoin therapy. This phenomenon is known and should be reported to the treating physician. In such cases, a dose adjustment or the short-term addition of an anti-inflammatory agent may be considered. The worsening is generally temporary and resolves in the further course of therapy.
May I exercise during isotretinoin therapy?
Exercise is generally possible during therapy; however, muscle and joint discomfort should be monitored, as isotretinoin can predispose to such complaints. Medical advice should be sought with intensive training or the occurrence of severe muscle pain. Adequate sun protection during outdoor exercise is also especially important.