Chemistry Reference
In-Depth Information
Figure 13:
Structures of selective COX-2 Inhibitors Celecoxib and Rofecoxib.
Procaine (Fig.
14
) was one of the first anesthetics synthesized by man and was
widely used in clinical until the introduction of more effective alternatives like
lidocaine (Fig.
14
). Procaine has a vasodilator effect and is often co administered
with a vasoconstrictor, like adrenaline, to reduce the bleeding and the clearance of
procaine of the local where it was injected. Procaine has an ester on its structure
and it's hydrolyzed in the plasma by the enzyme pseudocholinesterase, making it a
lasting drug. To avoid this hydrolysis, the ester was changed by an isosteric amide
and there are two
orto
-methyl groups in the aromatic ring, creating a steric shield
to the amide, leading to Lidocaine, a longer acting local anesthetic [40, 49, 50].
O
N
O
Procaine
H
2
N
N
N
O
Lidocaine
Figure 14:
Structures of local anesthetics Procaine and Lidocaine.
Nifedipine (Fig.
15
) is a calcium-channel antagonist administered orally in the
treatment of hipertension, despite its low bioavailability due to reduced
hidrosolubilityand the quick metabolic reduction of the aromatic nitro group.
Nifedipine is often formulated with polyvinylpyrrolidone (PVP) and
polyethyleneglycols (PEG) for a better dissolution and absorption by the gut wall.
