FIASMAs inhibit the ASM via an indirect, functional mechanism. They insert into the inner leaf of the lysosomal membrane and subsequently cause membrane-associated enzymes, such as ASM, to detach. Upon detachment from the membrane, these enzymes are cleaved and degraded within lysosomes. Inhibition of ASM by certain drugs has been known about for a long time, but systematic studies which characterize the pharmacological group of FIASMAs are relatively recent. ASM is not completely inhibited by FIASMAs and a low residual activity remains, allowing sufficient metabolism for cellular survival to occur. Application of FIASMAs therefore do not result in a clinical condition like Niemann-Pick disease, where ASM-activity is completely lacking because of genetic mutations.
