2. Introduction
Include: - Antibacterial
- Antiviral
- Antifungal
Antibiotic: - Chemical substance produced
by a micro organism which has capacity in
dilute solution to inhibit the growth of or kill
other organisms.
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3. Cont.
Chemotherapeutic agent- A drug which is
manufactured entirely by chemical symthesis.
e.g: Sulphonamide, trimethoprim
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4. Mechanism of action
Inibition of cellwall synthesis- Penicillin,
cephalosporin, vancomycin
Inhibition of cytoplasmic membrane -
antifungal antibiotics
" protein synthsesis & impairement of
function of ribosomes - Aminolgylocydes,
Macrolides
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5. CONT.
Interference in transcription and translation of
genetic information - Quinolones,
metronidazole
Antimetabolite action - Sulfonamide,
trimethoprim
Binding to viral enzymes essential for DNA
synthesis - Acyclovir
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6. Classifications
On the basis of family
Penicillins
Cephalosporins
Sulphonnamides
Aminoglycosides
Macrolides
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7. Cont.
On the basis of effect
Bacteriostatic: Erythromycin
clotrimoxazole
Sulfonamide
Bactericidal: Penicillins
Cephalosporins
quinolones
Aminoglycosides
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8. Selection of Antimicrobials
• Clinical evaluation and diagnosis of
antimicrobiological etiology.
• Study of culture & Sensitivity
• pregnancy and neonatal period
• Severity of disease
• Risk of toxicity of drug .
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9. Cont.
H/O Allergic reaction
Cost of therapy
Use of narrow spectrum antibiotic
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10. Antibiotic prophylaxis
Given in followings situation:
For preventing endocarditis following minor
surgeries.
In patients with compound musculoskeletal
injuries, penetrating wounds, skull injury,
rhinorrhea, otorrhea
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11. Cont.
• Prophylaxis regime for dental & oral procedure
– Amoxycillin: Adult 2.0g, children 50mg/kg orally 1 hr
before procedure.
– In Patient can't use oral –ampicillin - Adult- 2.0g i/m or
i/v & children 50mg/kg i/m or i/v 30min. before
procedure
– Allegric to penicillin- cephalexin adult 2.gm, child
50mg/kg oral, 1hr before procedure or
– Azithromycin adult 500mg, child. 50mg/kg oral 1hr
before procedure
– Allergic to penicillin and unable to take orally
clindamycin adult-600mg, child-50mg/kg 1hr before
procedure.
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12. Principles of antibiotic
administration:
Dosage: Should be adequate
In renal failure dosage should be decreased
e.g Aminoglycosides, vancomycin
In severe infection- large initial dose is used.
Duration: Should be given for Min. 4 to 5 days.
Severe infection -Duration can be prolonged
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13. Cont.
Route & Frequency of administration:
Antibiotic given by oral route should be acid
stable and absorbed from GIT e.g Penicllin
V, Amoxycillin
Use of narrow spectrum antibiotic:
To minimize risk of super infection with
resistant organism
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14. Beta - lactam Antibiotics
Include penicillins & Cephalosporins
Have B-Lactam ring
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15. Penicillins:
Classification
Natural: Penicllin G and Phenoxymethyl Penicillin
V.
Semisynthetic:- Short acting:- Ampicillin
-Amoxycillin
- Long acting: -Procaine penicillin, benzathene
penicillin.
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16. Cont.
Administration:
Oral Route-Safest & Commonly used.
i/m- Should be given only if surgery is equipped to
deal emergencies
i/v- Should be given only in hospitalized patients.
Penicillin are not given orally. Since adequate
level is not achieved.
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17. Cont.
Phenoxymethyl penicillin and ampicillin should be
given 1HR before or 3hrs after meals.
Amoxicillin can be given after food
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18. Cont.
• Measurements
– Expressed in I.U
– 250mg= 4,00,000 I.U
• TOXIC effects
– Allergy: Manifested as skin rash, Dermatitis, Serum
Sickness
– Controlled by withdrawal of penicillin use of
antihistamine
– Anaphylaxis- Life threatening - Characterized by -
Coughing, tonic spasms, Cyanosis, Weak Pulse,
Rapid drop in BP
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19. Cont.
Other Effects:
Pregnancy-1st choice-Amoxycillin
Lactation: Phenoxymethyl penicilin is preferred
Oral Contraceptives: Penicillins may render
OCP in - effective
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20. Cephalosporins
• Mode of action
– Bactericidal
– Inhibit cell wall synthesis
• Spectrum of activity
– Staphylococci
– Streptococci
• Indication:
– Alternative drug when penicillin is contraindication
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21. Cont.
Classification
1st Generation For Gram+ve Microorganisms &
gram –ve except enterococci e.g:- Cephalexin
Second generation:greater activity against gram
+ve organisms e.g Cefotaxime
Third Generation: Less activity against gram+ve
than first generation & more activity against
enterobacteria
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22. Erythromycin
Macrolide antibiotic
Available as azithromycin , Roxithromycin
Oral only
Broad Spectrum Antibiotic
Against Gram +ve resistant to penicillin & Gram
-ve Organisms.
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24. Cont.
Pharmacology
Oral preparation salt available as stearate or
estolate salt
Stearate salt is acid labile but less absorbed
Estolate: Well absorbed
i/M Preparation: erythromycin
i/V : Erythromycin Lactobionate is used
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25. Cont.
• Absorption:
– Absorbed from upper part of small intestine
– Food may delay absorption- So Given the before
food.
• Excretion:
– Excreted by liver and kidney
• Toxic Effect
– Allergic reaction-skin rashes
– Anaphylaxis
– Gastrointestinal effect- Nausea, vomiting,
diarrohea
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26. Cont.
• Interaction:
– Antihistamins
– Theophyllin
– Carbamazepine
– Warfarin
– Benzodiazepine
– Ocp
• Use in pregnancy & lactation
– Not teratogenic
– Appears in breast milk
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27. Sulfonamides and Trimethoprim
Bacteriostatic
Inactivated in presence of pus
Act by inhibitions of bacterial synthesis of folic
acid from para - amino benzoic acid
Absorption, distribution, excretion
Absorbed after oral administration
Distributed through all body fluids
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28. Cont.
Cross placental barrier & appears in breast milk
Excreted through kidney
Presence of sulfonamides in urine is greater than
in blood- leads to formation of crystals of
sulfonamide in urine called crystalurea & leads to
renal damage
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56. Metronidazole
In anaerobic infection
In anug
Spectrum:
Gram+ve & gram-ve including bacteriods
Indications:
Anug
C/c destructive periodontal desease
Juvenile periodontitis
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57. Cont.
Administration, absorption, distribution:
Absorbed through - GIT
Distributed in body fluids
Cross placental barrier
Appear in breast milk
Excretion:
In urine- coloured red or brown
In saliva
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