Pharmacokinetics. Once triggered, changes in DNA methylation can be self-perpetuating
within the cell. Thus, transiently altering DNA methylation can trigger permanent effects. In
this vein, even a single transient application of a methylation-altering drug may trigger lifelong
effects. In classical pharmacology, irreversible inhibitors such as covalent modifiers of enzyme
active sites are not even in the same ballpark—their effects last at most for the lifetime of the
target protein or molecule. DNA methylation manipulation potentially takes irreversibility to a
new level pharmacologically.