Chapter 16: Common Dermatologic Therapies
Routine Skin-Care Measures: Acne Medications
Benzoyl Peroxide
Benzoyl peroxide (BP) has several mechanisms of action helpful in acne, including antimicrobial, anti-inflammatory and comedolytic effects. It is available over the counter in preparations up to 5%, or as a prescription up to 10%. It is also available in combination with other acne medications (discussed below). Benzoyl peroxide can be irritating to the skin and so should be started slowly and increased as tolerated. Importantly, benzoyl peroxide bleaches clothing and towels, and patients should be warned of this prior to use!
Salicylic Acid
Salicylic acid is a keratolytic to exfoliate the top layer of skin. It is helpful in comedonal acne. For acne it can be purchased over the counter in concentrations of 0.5-2%. Salicylic acid can be irritating to the skin, and we recommend initially using several times a week before increasing to daily use.
Retinoids
Topical retinoids are a prescription form of Vitamin A and include tretinoin, tazarotene, trifarotene and adapalene. The price of these varies and some might be cost-prohibitive for certain patients.
- Adapalene gel or cream 0.1%, 0.3% (less irritating)
- Tretinoin gel or cream
- 0.01%, 0.025%, 0.05%
- 0.04%, 0.1% micronized (less irritating)
- Tazarotene gel or cream 0.05%, 0.1% (more irritating)
- Trifarotene cream 0.005% (for back acne)
Retinoids affect several genes within the cell that regulate the function of keratinocytes and the thickness of the epidermis. They are useful for the treatment of comedonal acne, wrinkles, thick psoriasis plaques, and actinic keratoses. They can be helpful in mild melasma or with photoaging spots. Finally, they are useful in wound healing and, when applied to early stretch marks, can aid in their healing. Retinoids should be applied at night to decrease their photosensitizing effect. Irritation is the main side effect and can be decreased by using several times per week initially and increasing to daily use as tolerated. Due to potential rick of absorption and subsequent teratogenicity, adapalene and tretinoin are pregnancy category C. Tazarotene is pregnancy category X and its use is prohibited during pregnancy.
Azelaic Acid
Azelaic acid is a natural product produced by Malassezia furfur, a normal commensal yeast on the skin. It is commercially available in 10 or 15% gel for the treatment of rosacea and has antibacterial, comedolytic and anti-inflammatory properties. These same properties make it useful for the treatment of acne as well. It is also used in disorders of hyperpigmentation including melasma and post-inflammatory hyperpigmentation.
Combination Topicals
Combining benzoyl peroxide with a topical antibiotic helps to decrease antimicrobial resistance. There are also combinations of topical retinoids with benzoyl peroxide or antibiotics. These help treat both the comedonal and inflammatory components of acne.
Commercially available combination products:
- Adapalene 0.1% + Benzoyl Peroxide 2.5%
- Adapalene 0.3% + Benzoyl Peroxide 2.5%
- Clindamycin 1% + Benzoyl Peroxide 5%
- Clindamycin 1.2% + Tretinoin gel 0.025%
- Erythromycin 3% + Benzoyl Peroxide 5%
