Additionally, for a drug product that is a solution for application to the skin (i.e., a topical solution), in vivo BE may be self-evident and a requirement of in vivo data for a product may be waived.The scientific principle is that if there is no difference in any aspect of the test product’s formulation compared to the RLD’s formulation that may significantly affect systemic or local availability, then BE between the test product and RLD is considered self-evident. This scientific principle applies to topical solutions as well as semisolid dosage forms.