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anti bacterial drugs > Anti bacterial drugs cell wall synthesis inhibitors 2 > Flashcards

Anti bacterial drugs cell wall synthesis inhibitors 2 Flashcards

1
Q

discuss the characteristics of Cephalosporins

A

They are similar to penicillin but are more stable to many bacterial beta lactamase and thus have a broader activity spectrum.

They are semi synthetic antibiotics

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2
Q

Which bacteria is resistant to all cephalosporins

A

Enterococci

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3
Q

Cephalosporin general rules

A

First generation is most effective against against gram positive

Fourth generation is similar to first generation and effective against gram negative

through chemical modification of the basic cephalosporins structure ,there is an increase in effectiveness of suceeding generations against gram neg aerobic organisms

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4
Q

How do bacteria develop resistance ?

A
  1. No cell wall
  2. Decreased permeability
  3. Bacteria do not grow
  4. Alterations in binding proteins
  5. β-Lactamase production
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5
Q

The pharmacokinetics of cephalosporins

A

Variable T1/2
• Ceftriaxone → 40% hepatic elimination
• Excretion → via kidney (can use probenecid to
increase t1/2 except ceftriaxone) (Drugs that block tubular secretion eg probenecid may increase serum levels ,thats why patients with impaired renal functions must be given i small doses
• Third generation → Penetrates well into CSF

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6
Q

Cephalosporins side effects

A
  1. Hypersensitivity reaction (anaphylatic shock ,fever ,skin rash ,nephritis ,granulocytopenia and hemolytiv anemia
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7
Q

Cephalosporins side effects

A
  1. Hypersensitivity reaction (anaphylatic shock ,fever ,skin rash ,nephritis ,granulocytopenia and hemolytiv anemia )
    * .Chemical structure differes enough from penicillin so that some people can tolerate them
    * Occurance of hypersensitivty occurs in 2% of population
  2. Some can also cause alcohol intolerance (cefamandole)
  3. Effectiveness of combined with contraception
  4. Nephrotoxicity ( co- administered with aminoglycosides or vancomycin)
  5. Phlebitis can occur via IV
  6. Neurotoxicity can occur at high doses
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8
Q

How does cephalosporin interact with other substances ?

A
  1. Alcohol ( with some cephalosporins)
  2. Warfarin
  3. NSAIDs
  4. Combined with oral contraceptives pills
  5. probenecid
  6. Cephalosporins and aminoglycosides in same container may chemically inactivate each other .
  7. Ceftriaxone ( not to be administered at the same time as calcium solutions for more than 48 hrs
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9
Q

Cautions/Contraindications

A
  1. Anaphylatic shock (PENICILLIN)
  2. ALLERGY
  3. Ceftriaxone contraindicated in hyperbilirubinemia neonates ( premature infants)
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10
Q

What are the characteristics of carbapenems?

A

They have a broad spectrum ( gram pos and neg anaerobic bacteria

Not active against methicillin resistant staphylococus

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11
Q

List the drug examples of Carbapenems

A 
Imipenem + cilastatin (enzyme inhibitor that blocks
renal metabolism)
• Meropenem
• Ertapenem (narrower spectrum)
• Doripenem (withdrawn in Europe)
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12
Q

What is the mechanism of action of carbapenems?

A

Bactericidal , same as penicillin

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13
Q

Uses of carbapenems

A
  1. Imipenem: Severe nosocomial infections ( septicemia, endocarditis and lower reparatory infection, GUT ,intra-abdominal,bone , skin, joints, and soft tissue infection )
  2. Meropenem: Alternative treatment for bacterial meningitis,it can penetrate the CSP
  3. Ertapenem : Single dose daily via IV
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14
Q

What are the side effects of carbapenems

A

1.Similar to other beta lactams (hypersensitivity reaction ,GIT effects ,haematological abnormalities ,CNS effects (seizures at high dosages of imipenem)
Increased liver enzymes
Increased serum creatinine and blood urea

  1. Red discoloration of urine in children(imipenem)
  2. IV : pain ,erythema and thrombophlebitis
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15
Q

Cautions and contradictions

A

1.Allergy
2 CNS disorders or seizures
3.Renal impairment

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16
Q

Give an example of monobactams

A

Aztreonam

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17
Q

Give the mechanism of action of monobactams

A

Bactericidal ,same as penicillin

18
Q

What is the spectrum of monobactams?

A

Their spectrum is limited to aerobic gram negative bacteria eg E.coli and p. Aeruginosa

19
Q

How are monobactams administered

A

IV or IM

20
Q

What are the side effects of monobactams?

A
  1. Injection site reaction
  2. Rash
  3. Rarely toxic epidermal necrolysis
  4. Gastrointerstinal side effects
  5. Drug induced eosinophilia
21
Q

Give an example of glycoprotein antibiotics

A

Vancomycin and Teicoplanin and fosfomycin

22
Q

What is the spectrum of vancomycin

A
  1. It is active against gram positive only
  2. It is a antibiotic reserved for treatment of life threatening infections
  3. It is an alternative treatment for endocarditis (in penicillin allergic patients)
23
Q

Use of vancomycin

A

Use is restricted to cloxacillin resistant staphylococci and penicillin resistant enterococci

24
Q

How is vancomycin administered

A
  1. In gastrointestinal tract infections (orally) and

2. No cross resistance with other anti biotics

25
Q

Action of mechanism of vancomycin

A
  1. bactericidial
  2. Inhibits cell wall synthesis
  3. Transglycosylation between side chains thus peptidoglycan cross-linkage does not form resulting in a weakened cell wall , eventually the bacterium lyses
26
Q

Discuss the Pharmacokinetics vancomycin

A
  1. Poorly absorbed when administered orally
  2. IM administration is painful
  3. The drug is only administered by IV infusion slowly
  4. It administered orally for pseudomembranous colitis
  5. Half life is 4 to 11 hours
  6. Excreted 80-90% unaltered via glomerular filtration in the urine
27
Q

What are the side effects of vancomycin

A
  1. fever and skin rashes
  2. When administered rapidly ,it causes histamine release ,causing blushing of the neck and face known as red man syndrom
  3. Ototoxic and nephrotoxic ,rare
  4. Nephrotoxic in geriatric
  5. Therapeutic drugs monitoring essential in elderly , children and impaired renal function
28
Q

Drug interaction of vancomycin

A

Ototoxic and nephrotoxic drugs eg aminoglycosides

29
Q

Cautions/Contraindications of vancomycin

A
  1. Renal Impairment
  2. Elderly patients
  3. Neonates/young infants
  4. Hearing abnormalities
  5. Pregnancy
30
Q

What are the mechanism of action of teicoplanin

A
  • Similar to vancomycin
    1. bactericidial
    2. Inhibits cell wall synthesis
    3. Transglycosylation between side chains thus peptidoglycan cross linkage does not form resulting in a weakened cell walll ,eventually the bacterium lyses
31
Q

Discuss the pharmacokinetics of teicoplanin

A

1.IM (painful)
Usually administered via IV
2.Half life is 45 to 70 hr ,thus give one dose a day

32
Q

what are the side effects of teicoplanin?

A

Same as vancomycin, lower
incidence of “red man” syndrome, allergy
(cross sensitivity with vancomycin)

33
Q

what is the spectrum of Fosfomycin

A

It is active against gram pos and gram neg ( broad spectrum

34
Q

What are the actions of mechanisms for the fosfomycin

A
  1. bactericidal

2. Inhibits early stages in bacterial cell wall synthesis

35
Q

What causes fosfomycin in resistance in bacteria

A

Inadequate transport of drug into cell

36
Q

Discuss pharmacokinetics of Fosfomycin

A

1.when administered orally ,absorption is delayed by food (takes two hours before meal)
2. Excreted in breast milk
Excreted in urin (30 to 60%)

37
Q

Uses of Fosfomycin

A

Uses:
1. Single-dose therapy for acute uncomplicated
lower urinary tract infections (sensitive E. Coli)
2. Prophylaxis in diagnostic and surgical
transurethral procedures

38
Q

what are the side effects of fosfomycin

A

GIT disturbances, skin rashes

39
Q

Drug interaction of fosfomycin

A

Metoclopramide → ↓ serum & urinary

concentrations of fosfomycin (avoid)

40
Q

Cautions/Contraindications of fosfomycin

A

C/I in renal failure

2. Caution → pregnancy & lactation

anti bacterial drugs (7 decks)

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