CHEMOTHERAPEUTIC
AGENTS
(ANTIBIOTICS)
PREPARED BY MR. ABHIJIT DAS
CEPHALOSPORINS
Cephalosporins are a class of
broad-spectrum antibiotics used to treat bacterial infections. They belong to
the beta-lactam group of antibiotics.
Cephalosporins contain a beta-lactam ring. This ring is crucial for the
antibacterial activity of these drugs.
CLASSIFICATION
1. First Generation Cephalosporins:
- Examples:
Cephalexin, Cefazolin
2. Second Generation Cephalosporins:
- Examples:
Cefuroxime, Cefoxitin
3. Third Generation Cephalosporins:
- Examples:
Ceftriaxone, Ceftazidime
4. Fourth Generation Cephalosporins:
- Example:
Cefepime
5. Fifth Generation Cephalosporins:
- Example:
Ceftaroline
MOA
The mechanism of action of cephalosporins
involves the beta-lactam ring inhibiting the activity of transpeptidase, an enzyme crucial for cross-linking the glycan and peptide chains in
bacterial cell walls (peptidoglycan). This
inhibition weakens the cell wall, leading to bacterial cell lysis and death.
ADVERSE EFFECTS
1.
Allergic Reactions:
Potential for allergic responses, especially in individuals with a history of
penicillin allergy.
2.
Gastrointestinal
Disturbances: May cause nausea, vomiting, or
diarrhea.
3.
Renal Impairment
4.
Hematologic Effects:
Blood disorders like leukopenia or thrombocytopenia can occur, but this is
uncommon.
5.
Antibiotic-Associated
Diarrhea: Can disrupt normal gut flora, leading to
diarrhea.
THERAPEUTICAL USES
1.
Respiratory Infections
2.
Urinary Tract Infections
3.
Skin and Soft Tissue
Infections
4.
Meningitis
AMINOGLYCOSIDES
Aminoglycosides are potent antibiotics
that disrupt bacterial protein synthesis. They
are often used for severe infections. Examples include Gentamicin, Tobramycin,
and Streptomycin.
MOA
The mechanism of action of aminoglycosides
involves binding to the 30S ribosomal subunit in
bacteria. This binding causes misreading of the mRNA (messenger
RNA) sequence during protein synthesis. As a result,
incorrect amino acids are added to the growing polypeptide chain,
leading to the production of nonfunctional or toxic
proteins.
ADVERSE EFFECTS
1.
Nephrotoxicity
2.
Ototoxicity
3.
Neuromuscular Blockade
4.
Allergic Reactions
THERAPEUTICAL USES
1.
Severe Bacterial
Infections
2.
Respiratory Tract
Infections
3.
Urinary Tract Infections
4.
Skin and Soft Tissue Infections
5.
Infective Endocarditis
TETRACYCLINES
Tetracyclines are a class of antibiotics
used to treat various bacterial infections. They
inhibit bacterial protein synthesis. Examples include:Doxycycline, Minocycline,
Tetracycline.
MOA
The mechanism of action of tetracyclines
involves binding to the 30S ribosomal subunit in
bacteria. This binding inhibits the attachment of
transfer RNA (tRNA) to the A site on the ribosome, disrupting the process of protein synthesis and
ultimately leading to the inhibition of bacterial growth.
ADVERSE EFFECTS
1.
Gastrointestinal Distress
2.
Photosensitivity
3.
Tooth Discoloration
(especially in children)
4.
Hepatotoxicity
5.
Renal Toxicity
THERAPEUTICAL USES
1.
Respiratory Tract
Infections
2.
Acne Vulgaris
3.
Urinary Tract Infections
4.
Lyme Disease
5.
Chlamydia Infections
(STD)
MACROLIDES
Macrolides are a group of antibiotics with
a large lactone ring in their chemical
structure. They are effective against both Gram-positive and some Gram-negative
bacteria.
Examples:Erythromycin, Azithromycin, Clarithromycin.
MOA
The mechanism of action of macrolides
involves binding to the 50S ribosomal
subunit in bacteria. This binding interferes with the translocation
process of growing peptide chains from the A
(aminoacyl) site to the P (peptidyl) site on the ribosome during
bacterial protein synthesis.
As a result, the elongation of the peptide
chain is disrupted, leading to inhibition of
bacterial protein synthesis and ultimately impeding bacterial growth.
ADVERSE EFFECTS
1.
Gastrointestinal
Disturbances
2.
Hepatotoxicity
3.
Cardiac Arrhythmias
(rare)
4.
Allergic Reactions
THERAPEUTICAL USES
1.
Respiratory Tract
Infections
2.
Skin and Soft Tissue
Infections
3.
Sexually Transmitted
Infections (e.g., Chlamydia)
4.
Legionnaires' Disease (a
severe form of pneumonia)
5.
Whooping Cough
(Pertussis)
SULPHONAMIDES
Sulphonamides, also known as sulfa drugs, are a class of antibiotics that
inhibit the growth of bacteria by interfering with their ability to synthesize
folic acid, an essential component for the production of DNA.
MOA
The mechanism of action of sulphonamides
involves inhibition of dihydropteroate synthase, an enzyme crucial for
the synthesis of folic acid in bacteria. Folic acid is essential for the
production of DNA. By interfering with this pathway, sulphonamides hinder
bacterial growth and replication, leading to their bacteriostatic effects.
ADVERSE EFFECTS
1.
Hypersensitivity
Reactions
2.
Skin Rash
3.
Gastrointestinal
Disturbances
4.
Hematologic Effects
(e.g., Hemolytic Anemia)
5.
Renal Effects (e.g.,
Crystalluria, Renal Damage)
THERAPEUTICAL USES
1.
Urinary Tract Infections
2.
Respiratory Tract
Infections
3.
Toxoplasmosis (caused by
the protozoan parasite Toxoplasma gondii)
4.
Nocardiosis
5.
Chlamydia Infections
FLUOROQUINOLONES
Examples: Ciprofloxacin, Levofloxacin,
Moxifloxacin
MOA
The mechanism of action (MOA) of fluoroquinolones involves the inhibition of
bacterial DNA gyrase and topoisomerase IV, two enzymes that are crucial for the
process of DNA replication, transcription, and repair in bacteria.
ADVERSE EFFECTS
1.
Tendon Rupture
2.
Central Nervous System
Effects (e.g., Dizziness, Headache)
3.
Photosensitivity
4.
Gastrointestinal
Disturbances (e.g., Nausea, Diarrhea)
THERAPEUTICAL USES
1.
Urinary Tract Infections
2.
Respiratory Tract Infections
3.
Skin and Soft Tissue
Infections
4.
Gastrointestinal
Infections
5.
Bone and Joint Infections