Chemistry Reference
In-Depth Information
Felodipine (Fig.
15
) uses bioisosteric substitution of the nitrobenzene group by a
dichlorobenzene to have better hidrosolubility and improved half-life, from 2 to
17 hours when compared with nidefipine, by avoiding the metabolic reduction
observed by the nitro group [49].
Cl
Cl
NO
2
O
O
O
O
O
O
O
O
H
H
Nifedipine
Felodipine
Figure 15:
Structures of Calcium Channel Antagonists Nifedipine and Felodipine.
Figure 16:
Structures of beta-lactamic antibiotics Penicillin G and Penicillin V.
Penicillin G (Fig.
16
) was the first antibiotic drug widely used by mankind, but
due to the high susceptibility of the beta-lactamic ring of its structure by acid
hydrolysis, it must be injected by intramuscular or intravenous ways to avoid
degradation by the gastric acid.The beta-lactamic ring is essential for the
mechanism of action of all penicillins, but the ring tension makes the carbonyl of
the beta-lactam more eletrophilic than other amides due to the lack of a dipolar
resonance between the carbonyl and the nitrogen that normally exists in amide
systems, this makes the beta-lactamic ring more susceptible to the attack of a
nucleophile, causing the acid sensitivity of the Penicillin G. In order to reduce this
