This document classifies penicillins into several categories based on their chemical structure. It lists various natural and semisynthetic penicillins, grouping them according to whether they are acid resistant, penicillinase resistant, extended spectrum, or other categories. Some of the main groups mentioned are natural penicillins like penicillin G; acid resistant penicillins like penicillin V; penicillinase resistant ones like oxacillin; and extended spectrum groups such as aminopenicillins, carboxypenicillins, ureidopenicillins, and amidinopenicillins.

1. CLASSIFICATION OF PENICILLINS
N
S
OR
2
O
H
R
3
N
H
R
1
O
O
Drugs R1 R2 R3
Natural penicillins
Penicillin G (Benzyl penicillin) H H
Penicillin F
H
H
C
H3
H H
Penicillin K C
H3 H H
Penicillin N
O
H
NH2
O H H
Penicillin O S
C
H2 H H
Penicillin X
O
H
H H
Semisynthetic penicillins
Acid resistant penicillins
Penicillin V
O
H H
Phenethicillin
O
CH3 H H
Propicillin
O
CH3 H H
Penicillinase resistant penicillins
Oxacillin
O
N
C
H3
H H
Cloxacillin
O
N
C
H3
Cl H H

2. Dicloxacillin
O
N
C
H3
Cl
Cl H H
Flucloxacillin
O
N
C
H3
Cl
F
H H
Methicillin
O
N
C
H3
O
C
H3
O CH3
H H
Nafcillin O CH3 H H
Extended spectrum penicillins
Aminopenicillins
Ampicillin NH2 H H
Amoxycillin NH2
O
H
H H
Epicillin NH2 H H
Bacampicillin NH2
O O CH3
CH3 O H
Pivampicillin NH2
O CH3
O
CH3
CH3
H
Carboxypenicillins
Carbenicillin O OH H H

3. Carfecillin
O O
H H
Carindacillin
O O
H H
Ticarcillin O OH
S
H H
Temocillin O OH
S
H OCH3
Ureidopenicillins
Azlocillin
NH
O
N
NH
O
H H
Mezlocillin
NH
O
N
N
O
S
O
O
CH3 H H
Piperacillin
NH
O
N
N
CH3
O
O
H H
Amidinopenicillins

4. Mecillinam
N
S
OH
O
H
H
N
O
N
H
Pivmecillinam
N
S
O
O
H
H
N
O
N
H
O
O
CH3
CH3
CH3