AUDIENCE THEORY -CULTIVATION THEORY - GERBNER.pptx
Antibiotics
1. Antibiotics
Antibiotics are the chemical substances obtained from various micro
organisms
First discovered antibiotic is Penicillin by Alaxander Flemming in 1940
Antibiotics are used to cure diseases caused by bacteria such as pneumonia,
tuberculosis, meningities
Conditions for a substance to act as antibiotics are as follows:
Should be effective at low concentration
Should not have toxic side effects
Must be effective against pathogens
Should be stored for a long time without appreciable loss of its activity
Should be highly stable so that it can be isolated easily and absorbed readily
Should be available at low cost
Should be completely eliminated from the body after its administration has
been stopped
2. Classification of antibiotics
Classification based on chemical structure:
Cyclic structure– cyclopentane , cyclohexane and
clycloheptane derivatives
Tetracycline antibiotics - tetracycline
Aromatic antibiotics - Chloramphenicol
Amino Glycoside antibiotics - streptomycin
Macrolides antibiotics – Erythromycin.
3. Chloramphenicol
Discovered by Ehrlich in 1947
Obtained by culture of “Streptomyces Venezuelae”
Properties
Stable neutral compounds
Bitter in taste
Sharp melting point
Soluble in organic solvents and sparingly soluble in water
Optically active
Molecular formula C H O N Cl
11 12 5 2 2
On hydrolysis it gives dichloro acetic acid & optically active base
On reduction with Sn/ HCl followed by diazotization & coupling
with β-naphthol – orange red dye
On acetylation in pyridine–shows the presence of two OH groups
4. Therapeutic uses
Effective against gram +ive and gram –ive bacteria
It’s the first broad spectrum antibiotic
Inhibits the growth of stephalococcus, streptococcus bacillus
Used in treatment of typhoid, pneumonia, ricketisia, urinary
tract infection, whooping cough, meningitis, plague, syphilis,
gonorrhea & dysentry
Employed in acute infections due to Haemophilus influenza
Can be used in the treatment of skin and eye infection
It is absorbed in a intestinal tract and diffused into tissues.
As it is insoluble in water it has to be administered in the form
of fine particles.
5. Structure, activity, relationship of
Chloramphenicol
Modification of para nitro phenyl group:
If the nitro group of phenyl ring of chloramphenicol is replaced by other
substituents like CN , their physiological activity is reduced
Shifting the nitro group from para position , reduces the anti-bacterial
activity
If phenyl ring of choloramphenicol is replaced by alicyclic or
hetrocyclic ring, then the resulting antibiotic is found to be less effective
Modification of Dichloroacetamide chain
If chloro group is replaced by bromo group , the antibacterial activity is
only 80% .
6. .
Modification of 1,3 propane diol
The propane diol group is essential for its antibacterial
activity
If the length of the propane is altered, the drug is deactivated
If the bulkier substituents are introduced activity is
decreased
STEREOCHEMISTRY:
cholramphenol has two asymmetrical carbon atom.
It can form 4 optically active isomers-D & L threo isomers
and D & L erythro isomers.
Erythro isomers- toxic & not used in medicine
L-threo isomer-biologically inactive.
D-threo isomer – biologically active.
7. Toxicity
Nitro group may contribute to bone marrow depression
and Fatal blood dyscrasia
Dosage
Adult dosage- 500mg every 6 hrs
MODE OF ACTION
It inhibits the growth of bacteria.
DOSAGE FORMS
available as: capsules, ear drops, eye ointment
8. Penicillin
Widely used antibiotic
Extracted from mould of “Penicillin notatum”
Belongs to a group of antibiotic called β-lactam Antibiotic
Basic structure contains thiozoline ring fused with β-lactam
ring
Two rings constitute the fundamental nucleus of group of
antibiotics referred as “PENICILLIN”
Chrysogunum- highest yield of penicillin
9. Therapeutic uses
Penicillin is effective against gram +ive and gram –ive coccai and some
gram +ive bacilli
It is bacteriostatic in action, but at certain concentration it acts as
bactericidal agents.
Inhibits synthesis of bacterial cell wall
Non-toxic even in large doses.
Effective against pneumocccal infections, streptococcal infections,
staphylococcal infections, meningococcal infections.
Used in the treatment of diphtheria, gangrene, tetanus, etc
Used topically, orally or parentally
In oral therapy, the dosage must be given in larger doses as it is inactivated
by gastric acids
Sodium or potassium salt are used for injection
Calcium salt can be used as an ointment or as powder
10. .
Adverse effects
adverse effects like vomiting, nausea, anyphyxis and allergic
reactions
Natural penicillin are inactivated faster by HCL acids, variety
of semi synthetic and synthetic penicillin are produced that are
made effective
All these have allergic reactions similar to those produced by
natural penicillin.
11. Types of penicillin &Properties
Types of penicillin
Natural penicillin
Semi synthetic penicillin
Properties
Optically active
Soluble in water
Hydrolyzed by hot inorganic acids
Acid resistant
Effective in treatment of respiratory tract infection, streptococcal infections
and pneumonococcal infections
Methicillin is resistant to penicillinase and used in treatment of infection
resistant to benzyl penicillin
Ampicillin is effective against influenza, gonorrhea, salmonella typhose, e-
coli, etc.
12. Mode of action
Bacteriostatic and bacteriocidal
Anti-bacterial against organism mainly their growth phase
Interferes with synthesis of ribonucleic acid
13. Tetracyclins
Tetracyclins compress a group namely:
Tetracyclins
Chlorotetracyclins
Oxytertacyclins
Most important anti-microbial property
Obtained from the species of actinomyces named as streptomyces
Precipitated from a culture medium maintained at a pH 8-10 in presence of divalent cations
Can be separated by ion exchange chromatography
14. Therapeutic uses
Effective against gram+ive and gram –ive micro-organisms
Bacteriostatic
Inhibit essential enzymes in bacterial cell
Prevent synthesis of ribosomes
Used in treatment of infections such as pneumonia,
actinomycosis, urinary infection, spotted fever, typhus fever,
gonorrhea, syphilis,plague, ricketisia, etc.
Oromycin is effective against many bacteria similar to
cholorominphenicol but is not as effective as
chloramphenicol against typhoid fever
15. .
Less toxic drug, tolerated by patients
Tetramycin is more stable than oramycin
Used in treatment of conjunctivitis, cholera, amoebic
dysentery, etc.
Its effective against pneumonococci, streptococci, H-
influenza, e-coli, M-tuberculosis
Absorbed in duodenum and small intestine
Long duration of anti-bacterial action
They form insoluble complexes with calcium and magnesium
Substances like milk which contain calcium and antacids
reduce their absorption
Not advisable for children and pregnant women
16. Chemical properties
Yellow, odourless, crystalline powder with bitter taste
Sparingly soluble in water
Oxidized by oxygen in air, they darken when exposed to air
Amphoteric in nature , basicity is due to N-amino group and
acidity is due to phenolic group
Form chelates with metal ions
Due to the presence of phenol, it gives colour with neutral
ferric chloride and forms azo dye
Gives florescence in presence of UV light
17. Streptomycin
Belongs to the important amino glycosidic group of antibiotic
It is given the name from streptomyces
Organism producing the antibiotic is known as “Streptomyces
Griseus”
Other examples of amino glycosidic antibiotics are
gentamycins, neomycins
18. Therapeutic uses
Used in treatment of tuberculosis, infections of e-coli, H-
influenza, plague, respiratory tract infection, meningities
Bactericidal properties
Disturbs the normal protein synthesis and bacteria
Destroyes the cell membrane
19. Properties
Colourless solid
Dissolves in water but soluble in organic
solvents
Optically active and Leavoratotary
Basic in nature
21. Rifamycin
It is isolated from “Streptomyces mediterranei”
Belongs to a new class of antibiotics called “Ansamycins”
There are five types of rifamycis A,B,C,D,E
Cant be administered orally
Given intravenously
22. Therapeutic uses
Inhibits the growth of gram +ive bacteria such as e-coli, keri
bacila
Effective against staphylococcus
Acts by blocking the biosynthesis of nucleic acid of bacteria
Used in the treatment of tuberculosis
23. Properties
Reddish brown crystalline powder
Slightly soluble in water, completely in methanol
It exist as a “zwitter ion”
24. Cephalosporins
Isolated from the fungi “Cephalosporium acremonium” in 1948
They are β-lactum antibiotic with same fundamental structure as penicillin
It contains dihydro-meta thiazine ring
Most acid stable than penicillin
Classification of cephalosporin
Cephalosporin N
Cephalosporin P
Cephalosporin C
Cephalosporin C is true cephalosporin
25. Therapeutic uses
Used in the treatment of urinary tract infections, streptococcal
infections, pneumonia, tonsillitis, skin infections, etc.
Inhibits cross linking of peptide units in bacterial cell wall
26. CIPROFLOXACIN
They have been divided into four generations
This division is chronological order, the overall antibacterial
spectrum as well as potency.
It is the most potent first generation fluoroquinolones active
against broad range of bacteria-aerobic gram -tve bacilli & gram
+tve bacteria at higher concentrations.
important feature- tissue penetrability.
27. THERAPEUTIC USES
Effective against urinary tract infections,typhoid,bone,soft tissue
gynaecological and wound infections,respiratory infections,
tuberculosis, meningitis and conjunctivitis
First choice drug- typhoid cells since chloramphenicol,
amphicillil and cotrimaxazole are unreliable due to development
of resistance.
Used as a component of combination of multi drug treatment of
tuberculosis and respiratory infections.
28. MODE OF ACTION
It is rapidly absorbed orally but food delays absorption
high tissue penetrability
concentration in lung muscle and bone
Excreted by urine
ADVERSE EFFECTS
Produces nausea, vomiting and bad taste
Cause head aches, anxiety & insomnia,some times rashes on
the skin.
not admistered to children- damage to weight bearing joints.
29. CARBAPENEMS
Extremely potent and broad spectrum antibiotic.
It is a β-lactone antibiotic
resistant to β-lactinases.
limiting feature of imipenim is rapid hydrolysis by enzyme
peptidase located in the border of renal tubular cells.
effective in treatment of hospital acquired infections- cancer &
AIDS
Activity include gram +tve cocci and enterobacteriaceae
It cause seizuse at higher doses.