Drug Metabolism in Drug Design and Development Basic Concepts and Practice

The cumulative cost of bringing a drug to market is staggering. Without
some assurance that these costs will be recovered through eventual sales, it is
economically untenable to take on the high risks of failure attendant with drug
development. This fiscal assurance is provided, in part, through various patents
assigned during discovery and development. Patents covering composition of
matter are among the most valuable for a novel drug, as this allows the patent
holder exclusive rights for a reasonable period of time. Eventually, much of the

N

N

Cl

O

OH

N

N

OOC 2 H 5

Cl

NHCCH 3

OCH 2 CH 3

O

Cl

HO

N

OH

NHCCH 3

OH

O

N

H

N

Cl

Cl

HO

N

OH

OH

O

N

N

Cl

O

OH

O

Loratadine Destoratadine

Hydroxyzine Cetirizine

Terfenadine Fexofenadine

Phenacetin Acetaminophen

FIGURE 1.1 Examples of biotransformation reactions leading to a preferred
marketed drug (Fura et al., 2004).

REGULATORY IMPACT AND IP POSITION 11