Chemistry Reference
In-Depth Information
CH
3
N
O
O
CH
3
O
O
NH
2
H
2
N
O
CH
3
OH
H
3
C
O
Meprobamate
Pethidine
O
NH
CH
3
OH
N
O
O
N
Phenacetin
O
H
3
C
Phenylbutazone
CH
3
O
H
2
N
N
O
CH
3
Procaine
Figure 11.7
The structures of drug metabolites.
Phase 1 reactions are sometimes described as 'non-synthetic'
reactions and involve chemical modification of functional groups
in the drug molecule (hydrolysis, oxidation, etc.). Polar groups
are introduced, or existing polar functional groups are
unmasked. The Phase 1 derivative is usually more water soluble
(hydrophilic) than the parent drug. A Phase 2 (or 'synthetic')
derivative usually involves covalent bond formation to yield a
water-soluble conjugate (e.g. glucuronide, sulfate). Phase 2 reac-
A5.2
