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A 22-year-old woman presents with moderate comedonal and inflammatory acne on her face. She has not previously used a topical retinoid. She is sexually active and uses oral contraception. She asks about starting a "retinol" she has seen advertised.
Questions
a) Classify the topical retinoids and state which is the preferred first-line agent for acne, with the rationale. (2 marks)
- Four prescription generations: tretinoin (1st), tazarotene (2nd), adapalene (3rd), trifarotene (4th). OTC precursors: retinol, retinaldehyde.[1]
- Adapalene 0.1% gel is first-line for acne because it is photostable, the least irritating, RAR-beta/gamma selective, and compatible with benzoyl peroxide (available as OTC and in fixed-dose Epiduo).[2][3]
b) Describe the mechanism of action of topical retinoids. (2 marks)
- Bind nuclear RAR-alpha/beta/gamma receptors (forming heterodimers with RXR) that modulate gene transcription at retinoic acid response elements (RAREs).[1]
- Four clinical effects: (1) comedolysis — normalise follicular keratinocyte desquamation; (2) anti-inflammatory — suppress neutrophil chemotaxis and TLR-2; (3) collagen synthesis stimulation — upregulate procollagen I/III; (4) melanin transfer inhibition.[1][2]
c) Outline your counselling for application technique and expected side effects. (3 marks)
- Application: pea-sized amount to DRY skin 20 min after washing; to the ENTIRE face (not spot treatment); at NIGHT; start EVERY OTHER NIGHT for 2 weeks then nightly.[2]
- Adjuvants: non-comedogenic moisturiser (sandwich method); sunscreen SPF 30+ every morning; avoid concurrent irritants (AHAs, BHAs, astringents, waxing) initially.[2]
- Expected side effects: retinoid dermatitis (erythema, dryness, peeling, burning) worst at weeks 2-6; initial acne flare ("purging") at 2-4 weeks — counsel to PERSIST; visible improvement at 8-12 weeks; maximum benefit at 3-6 months.[2]
d) What advice would you give regarding pregnancy and drug interactions? (3 marks)
- Pregnancy: all topical retinoids avoided in pregnancy. Tazarotene is Category X (absolute contraindication; requires negative pregnancy test + reliable contraception). Tretinoin, adapalene, trifarotene are Category C (avoid). Safe alternatives in pregnancy: azelaic acid 15-20%, benzoyl peroxide, topical clindamycin.[1][3]
- Drug interaction with benzoyl peroxide: BPO OXIDISES tretinoin to inactive products — apply at different times (BPO AM, tretinoin PM) or use BPO-stable adapalene (fixed-dose Epiduo).[2]
- Since she is on oral contraception, advise that topical retinoids are suitable but she should continue reliable contraception; counsel against pregnancy while using any retinoid.[3]
References3ShowHide
- [1]Khalil S, Bardawil T, Stephan C, et al. Retinoids: a journey from the molecular structures and mechanisms of action to clinical uses in dermatology and adverse effects. Journal of Dermatological Treatment, 2017.PMID 28318351
- [2]Kolli SS, Pecone D, Pona A, et al. Topical Retinoids in Acne Vulgaris: A Systematic Review. American Journal of Clinical Dermatology, 2019.PMID 30674002
- [3]Reynolds RV, Yeung H, Cheng CE, et al. Guidelines of care for the management of acne vulgaris. Journal of the American Academy of Dermatology, 2024.PMID 38300170