The origin of the name tretinoin is uncertain,   although several sources agree (one with probability,  one with asserted certainty  ) that it probably comes from trans- + retinoic [acid] + -in , which is plausible given that tretinoin is the all-trans isomer of retinoic acid . The name isotretinoin is the same root tretinoin plus the prefix iso- . Regarding pronunciation, the following variants apply equally to both tretinoin and isotretinoin . Given that retinoic is pronounced / ˌ r ɛ t ɪ ˈ n oʊ ɪ k / ,     it is natural that / ˌ t r ɛ t ɪ ˈ n oʊ ɪ n / is a commonly heard pronunciation. Dictionary transcriptions also include / ˌ t r ɪ ˈ t ɪ n oʊ ɪ n / ( tri- TIN -oh-in )   and / ˈ t r ɛ t ɪ n ɔɪ n / .  
Corticosteroids are generally teratogenic in laboratory animals when administered systemical-ly at relatively low dosage levels. The more potent corticosteroids have been shown to be ter-atogenic after dermal application in laboratory animals. There are no adequate and well-controlled studies in pregnant women on teratogenic effects from topically applied corticosteroids. Therefore, topical corticosteroids should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus. Drugs of this class should not be used extensively on pregnant patients, in large amounts, or for prolonged periods of time.