pencillins - PowerPoint PPT Presentation

View by Category
About This Presentation
Title:

pencillins

Description:

pencillins – PowerPoint PPT presentation

Number of Views:163
Slides: 18
Provided by: shivaram49
Tags:

less

Write a Comment
User Comments (0)
Transcript and Presenter's Notes

Title: pencillins


1
PENCILLINS
  • BY.
  • T.SHIVAKUMR
  • Shiva.pharmacist_at_gmail.com

2
PENICILLINS
  • Beta- lactam antibiotics
  • Derivatives of 6- aminopenicillanic acid
  • Alteration of the side group resulted in cpds
    with
  • Broader spectrum of activity
  • Resistance to penicillinase
  • Stability in acid PH
  • Most widely effective antibiotics
  • Least toxic drugs known

3
(No Transcript)
4
MECHANISM OF ACTION
  • They act by inhibition of bacterial cell wall
    synthesis
  • Thus exposing the osmotically less stable
    membrane
  • This cause lysis of bacterial cell wall
  • These agents are bactericidal
  • Active against multiplying and not resting
    bacteria
  • Inactive against mycobacteria, protozoa, fungi
    and viruses

5

Classifications of penicillins
1.Penicillin G ( Benzyl penicillin )(i.m ,slow
i.v or infusion) Highest activity against
Gram-positive organisms but susceptible to
Beta-lactamase. Effective against
Gram-positive aerobic cocci - Staph. aureus- not
producing penicillinase,

S.pneumoniae ( group A ) ,S.pyogenes
Gram-negative aerobic cocci -N.meningitidis

N. gonorrhea-no longer of choice Gram-
positive bacilli Bacillus anthracis
Spirochetes T. pallidum drug of choice
Anaerobes Clostridium spp but inactive
against B.fragilis Actinomycetes
israelii ( actinomycosis )
6
  • Repository penicillins
  • Developed to prolong duration of penicillin G in
    the blood
  • Penicillin G procaine
  • Duration 12- 24 hr
  • It is given i.m and not i.v( risk of
    procaine toxicity)
  • Seldom used now ( increased frequency of
    penicillinase producing N. gonorrhea

7
  • Repository penicillins ( cont.)
  • 2. Penicillin G benzathin ( i.m )
  • Duration 3- 4 weeks
  • Painful at the injection site ( limits its
    use )
  • Uses
  • 1. Syphilis
  • 2. Rheumatic fever prophylaxis( inhibits
  • group A beta- hemolytic streptococci)
  • 3. Streptococcal pharyngitis

8
Class. Of penicillins ( cont. )
  • Disadvantages of penicillin G
  • A. Destroyed by gastric HCL
  • B. Inactivated by penicillinase
  • C. Narrow spectrum of activity

9
Class. Of penicillins ( cont. )
  • 2. Acid resistant penicillins
  • Phenoxy- methyl penicillin ( penicillin v),
    p.o.
  • ( spectrum of activity is similar to
    penicillin G )
  • Uses
  • Group A Streptococcal pharyngitis
  • Prophylaxis against group A streptococci in
    patients with history of rheumatic heart disease.
  • Disadvantages
  • Readily hydroyzed by beta-lactamase

10
Class. Of penicillins ( cont. )
  • 3. Penicillinase-resistant penicillins
  • Methicillin Oxacillin
  • Cloxacillin Dicloxacillin
  • Floxacillin Nafcillin
  • Lower activity against G compared to Penicllin G
  • but
  • Are the choice for infections caused by
    penicillinase producing S. aureus.
  • However, MRSA ORSA has emerged.
  • Not effective against G- aerobes( E.coli,
    klebsiella,N.gonorrhea or pseudomonas spp.)
  • Less active than penicillin on anaerobes.
  • High protein and food binders

11
Class. Of penicillins ( cont )
  • 4. Broad- spectrum penicillins
  • a) Ampicillin, Ampicillin- sulbactam,
    Bacampicillin, Amoxicillin, Amoxicillin-
    clavulanic acid ( augmentin ).
  • Less active than penicillin G against G cocci.
    Active against G- organisms.

12
Broad-spectrum penicillins ( cont )
  • Uses
  • H. Influenza infections ( otitis media,
    sinusitis, chronic bronchitis, pneumonia,
    bacterial meningitis ).
  • M.catarrhalis
  • E. Coli infections ( Urinary biliary infections
    ).
  • Samonella infections ( typhoid fever )
  • Shigella infections ( ampicillin )
  • Gonococcal infections ( alternative for
    penicillin in the treatment of gonorrhea )
  • Prophlaxis of infective endocarditis
  • Disadvantages
  • Amoxicillin ampicillin alone are readily
    destroyed by Staph. Penicillinase.

13
Broad spectrum penicillins ( cont )
  • B ) Extended- spectrum Ticarcillin-clavulanic
    acid, piperacillin,piperacillin-tazobactam (
    Tazocin )
  • Uses
  • Pseud. aeruginosa. For pseud.septicemia, they
    should be given together with an aminoglycoside
  • ( eg. Gentamicin ).
  • Disadvantages
  • Ticarcillin and piperacillin alone are readily
    destroyed by S. penicillinase. High dose may lead
    to hypernatraemia due to sodium content.

14
Absorption,distribution metabolism
  • Oral absorption of most penicillins is poor
  • Exception penicillin v
  • Amoxicillin
  • Food interfer with absorption
  • To increase GI absorption give ester form

  • Bacampicillin

  • Carbenicillin indany
  • Distribution
  • Widely distributed
  • Relatively insoluble in lipid
  • Hence, have poor penetration into cells and
    BBB
  • Inflammation ( eg. Meningitis ) permits
    entrance into CSF

15
Absorp., metabolism ( cont. )
  • Protein binding differs
  • Ampicillin and penicillin G 20 bound
  • Nafcillin, oxacillin, 90
    bound
  • cloxacillin , dicloxacillin
  • Metabolism and excretion
  • Not metabolized in human
  • Excreted mostly unchanged in urine( except.
    Nafcillin,oxacillin, cloxacillin,
    dicloxacillin )
  • Probenecid blocks their secretion
  • Half-life 30-60 min ( increased in renal
    failure)

16
Adverse effects of penicillins
  • 1.Hypersensitivity reactions ( occur in 1-10 of
    pts

  • fatality occur in 0.002)
  • ( immediate, accelerated late allergic rxns)
    Cross-reactions
  • Urticarial rash
  • Fever
  • Bronchspasm
  • Serum sickness
  • Exfoliative dermatitis
  • Stevens- Johnson syndrome
  • Anaphylaxis
  • 2. Super infections
  • 3. Diarrhoea
  • 4. May cause convulsions after high doses by i.v
    or in renal failure

17
THANQ
  • shiva.pharmacist_at_gmail.com
About PowerShow.com