Which is correct regarding the use of isotretinoin in the treatment of acne?

Isotretinoin is a potent systemic retinoid commonly used in the treatment of severe acne, particularly nodular acne that has not responded to other therapies. One of the most critical considerations in its use is its teratogenic effects, which can lead to severe birth defects if taken during pregnancy. Therefore, it is contraindicated in pregnancy, and women of childbearing age are required to use effective contraception during treatment with isotretinoin.

The other choices presented do not accurately reflect the characteristics or recommended use of isotretinoin. For instance, isotretinoin is not typically used topically; it is an oral medication. It does not act on corticosteroid receptors; instead, it works on retinoid receptors to modulate cell growth and differentiation in the skin, reducing sebum production and inflammation. Furthermore, isotretinoin is not meant for milder forms of acne; it is generally reserved for more severe or treatment-resistant cases. Thus, recognizing the teratogenic risk emphasizes the importance of the contraindication in pregnancy, making this answer the correct choice.