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Beta lactam antibiotics
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
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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
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
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