The invention relates generally to transdermal and transmembrane delivery of biologically active substances through the skin, sub-dermal tissues, blood vessels and cellular membranes without causing damage to the cellular surface, tissue or membrane. The invention provides compositions and methods for enhanced transdermal and transmembrane delivery of biologically active substances using pulsed incoherent light. The invention further provides a device for the application of the pulsed incoherent light to cellular surfaces and membranes using those compositions and methods.