Which medication is known to cause microtia?

The medication associated with the development of microtia is isotretinoin. Isotretinoin, a retinoid commonly used for severe acne, has been linked to various congenital malformations when used during pregnancy. Microtia, which is a condition characterized by the underdevelopment of the external ear, can occur as a result of isotretinoin exposure, especially during the critical periods of ear development in the first trimester.

Isotretinoin exerts its effects by interfering with normal cellular growth and differentiation, and its teratogenic effects are well-established. The risk of developing microtia, among other anomalies, highlights the importance of effective contraception and monitoring during isotretinoin treatment in individuals of childbearing potential.

Thalidomide is also notorious for causing limb malformations and other congenital defects, but it is more specifically associated with limb reduction defects rather than microtia. Trimethidone is not well-documented as a teratogen and is not recognized for causing microtia. Warfarin is known to lead to a spectrum of birth defects termed "fetal warfarin syndrome," which may include nasal and skeletal abnormalities, but it does not specifically cause microtia.