Human serum albumin (HSA) is one of the abundant transporter proteins present in the blood. HSA has multiple binding sites due to its ability to adapt to accommodate drug molecules. There is a general lack of studies as to which types of drugs or specific tautomers binds in particular HSA sites. However, there are many examples where one enantiomer is reported to bind tightly and the other weakly or with a different binding strength. Drugs usually form reversible complexes with HSA by electrostatic and hydrophobic forces, and strong binding may significantly affect the pharmacokinetic properties.