PF-4981517 is a potent and selective inhibitor of CYP3A4 (P450) with IC50 of 0.03 uM, exhibits >500-fold selectivity over CYP3A5 and CYP3A7. PF-4981517 is a very useful tool for understanding the relative roles of CYP3A4 versus CYP3A5 and the impact of CYP3A5 genetic polymorphism on a compound's pharmacokinetics.

SRPIN340 was investigated as selective serine arginine protein kinase (SRPK) 1 inhibitor, it also could inhibit SRPK2 at higher concentrations, but did not significantly inhibit other SRPKs such as CLK1 and CLK4, or other classes of SR kinases. It was shown, that SRPIN340 targeted host proteins, and might be effective against multiple hepatitis C virus (HCV) genotypes. Furthermore, the toxicity data available for SRPIN340 were promising and no adverse effects were observed when SRPIN340 was administered orally to rats. On the other hand, the fact that this inhibitor acted through cellular components still raises concerns regarding its safety in the case of human use. Future studies with SRPIN340, its derivatives, and other chemicals that target SRPKs could be directed toward developing a new class of antiviral treatment regimens and drugs.