This document summarizes beta lactam antibiotics, which contain a beta lactam ring in their structure. The two major groups are penicillins and cephalosporins. Penicillin was the first antibiotic discovered in 1928 and was the first to be used clinically to treat infections. Beta lactam antibiotics work by inhibiting the transpeptidase enzyme involved in bacterial cell wall synthesis, resulting in cell lysis. While effective, they can cause adverse effects like hypersensitivity reactions and toxicity. Semisynthetic derivatives were created to improve properties like oral efficacy, spectrum of activity, and resistance to degradation.

1. BETA LACTAM
ANTIBIOTICS
Presented by
Grandhi Sandeep Ganesh
Dept. Of Pharmacology
Shri Vishnu College of Pharmacy (Autonomous)
Affiliated to Andhra Univ., Visakhapatnam; Approved by AICTE and PCI, New Delhi, and recognised by APSCHE
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2. BETA LACTAM ANTIBIOTICS
These are the antibiotics contains
BETA LACTAM ring in their
structure
The two major groups containing
beta lactam ring are
Penicillins
Cephalosporins
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3. PENICILLINS
Penicillin was discovered by scientist Alexander Fleming
 penicillin is obtained from Penicillium notatum or P. chrysogenum
It was discovered in 1928
Penicillin was the first antibiotic to be used clinically in 1941
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4. Interfere with synthesis of bacterial cell wall
Usually the bacterial cell wall is composed of peptidoglycan
N- acetylmuramic acid
N- acetylglucosamine
Peptidoglycan residues are linked together and UDP is split off
Final step is cleavage of terminal D-alanine of the peptide by transpeptidase,
process known as transpeptidation
This cross linking provides greater strength of bacterial cell wall
Beta lactams inhibit the transpeptidase so that cross linking does not take
place
This results in cell wall deficient forms are produced and lysis of bacteria
takes place
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MECHANISM OF ACTION

5. MECHANISM OF ACTION
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CLASSIFICATION

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PENICILLIN-G
Penicillin-G is a narrow spectrum
antibiotic
Its activity is limited primarily to gram-
positive bacteria, few gram negative
ones and anaerobes.
It is the drug of first choice for many
infections

8. Local irritancy and direct toxicity: Pain at i.m. injection site, nausea
on oral ingestion
Toxicity to the brain may be manifested as mental confusion,
muscular twitching, convulsions and coma, when very large doses are
injected through i.v route
 Accidental i.v. injection of procaine penicillin produces CNS
stimulation, hallucinations and convulsions
Hypersensitivity: rash, itching, urticaria and fever. Wheezing,
angioneurotic edema, serum sickness and exfoliative dermatitis
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ADVERSE EFFECTS

9. In rare cases,
Swelling of the tongue, throat and lips
Respiratory symptoms such as difficulty breathing, coughing, chest
tightness, wheezing
Light-headedness
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ADVERSE EFFECTS

10. Semisynthetic penicillins are produced by chemically combining
specific side chains in place of benzyl side chain of PnG
The aim of producing semisynthetic penicillins has been to overcome
the shortcomings of PnG
 Poor oral efficacy.
Susceptibility to penicillinase.
 Narrow spectrum of activity.
Hypersensitivity reactions
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SEMISYNTHETIC PENICILLINS

11. ACID-RESISTANT: Phenoxymethyl penicillin (Penicillin V)
It differs from PnG only in that it is acid stable. Oral absorption is better; peak
blood level is reached in 1 hour and plasma t½ is 30–60 min.
PENICILLINASE-RESISTANT PENICILLINS: Methicillin,
Cloxacillin, Dicloxacillin
These congeners have side chains that protect the β-lactam ring from attack by
staphylococcal penicillinase
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SEMISYNTHETIC PENICILLINS

12. AMINOPENICILLINS: Ampicillin
It is active against all organisms sensitive to PnG. In addition, many
gram-negative bacilli, e.g. H. influenzae, E. coli, Proteus, Salmonella
Shigella and Helicobacter pylori are inhibited.
USES
Urinary tract infections
Respiratory tract infections
Meningitis
Gonorrhoea
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EXTENDED SPECTRUM PENICILLINS

13. Carboxypenicillins: Carbenicillin
The special feature of this penicillin congener is its activity
against Pseudomonas aeruginosa and indole positive Proteus which are
not inhibited by PnG or aminopenicillins.
Ureidopenicillins: Piperacillin
This antipseudomonal penicillin is about 8 times more active than
carbenicillin. It has good activity against Klebsiella, It is frequently
employed for treating serious gram negative infections in
neutropenic/immunocompromised patients
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EXTENDED SPECTRUM PENICILLINS

14. Beta-lactamase inhibitors can block the activity of beta-lactamase
enzymes and prevents the degradation of beta-lactam antibiotics
β-lactamases are a family of enzymes produced by many gram-
positive and gram-negative bacteria that inactivate β-lactam antibiotics
by opening the β-lactam ring
Clavulanic acid
Obtained from Streptomyces clavuligerus, it has a β-lactam ring
but no antibacterial activity of its own. It inhibits a wide variety of β-
lactamases produced by both gram-positive and gram-negative bacteria
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BETA-LACTAMASE INHIBITORS

15. Bacterial meningitis : benzylpenicillin
Bone and joint infections : flucloxacillin
Skin and soft tissue infections : benzylpenicillin, flucloxacillin
Otitis media : amoxicillin
 Bronchitis : amoxicillin
Pneumonia : amoxicillin
Urinary tract infections :amoxicillin
Gonorrhea : amoxicillin
Syphilis : procaine benzylpenicillin
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USES

16. Cephalosporins are a group of
semisynthetic antibiotics derived
from ‘cephalosporin-C’ obtained
from a fungus Cephalosporium
The nucleus consists of a β-lactam
ring fused to a dihydrothiazine
ring,(7-aminocephalosporanic acid)
All cephalosporins are bactericidal
and have the same mechanism of
action as penicillin
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CEPHALOSPORINS

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CLASSIFICATION

18. Pain after i.m. injection occurs with many cephalosporins
Diarrhoea
Hypersensitivity reactions Rashes are the most frequent manifestation,
but anaphylaxis, angioedema, asthma and urticaria have also occurred
in rare cases
Nephrotoxicity
Neutropenia and thrombocytopenia are rare adverse effects
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ADVERSE EFFECTS

19. As alternatives to penicillins for upper respiratory and cutaneous
infections
urinary and soft tissue infections caused by gram-negative organisms
Septicaemias caused by gram-negative organisms: cefuroxime,
cefotaxime
 pneumonia
Meningitis: ceftriaxone, cefotaxime
 biliary tract infection
 urinary tract infection
 sinusitis: cefadroxil
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USES

20. MONOBACTAMS
The main monobactam is aztreonam , which is resistant to most β-
lactamases effective only against Gram-negative aerobic bacilli
CARBAPENEMS
Imipenem, an example of a carbapenem, acts in the same way as the
other β-lactams being active against many aerobic and anaerobic
Gram-positive and Gram-negative organisms
It is resistant to most β-lactamases, inhibits penicillinase producing
staphylococci
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OTHER BETA LACTAM ANTIBIOTICS

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