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cph 1902 > antibiotics > Flashcards

antibiotics Flashcards

1
Q

what is pharmacokinetics?

A

what body does to drug (L, A,D, M,E)

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2
Q

What is pharmacodynamics?

A

what drug does to body

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3
Q

what is MIC ( minimum inhibitory concentration) & MBC (minimum drug- concentration)?

A

minimum inhibitory concentration :
- minimum drug concentration INHIBITING MICROBIAL GROWTH in virtro

minimum bacteriocidal conc
- Minimum drug concentration that KILLS MICROBES IN VITRO

MBC is 2-4 fold of mIC

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4
Q

concentration to MIC (Cmax : MIC)

A

every dose’s concentration spikes and goes down.

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5
Q

area under curve to MIC

A

drug effectiveness is affected by AMOUNT OF TIME SPENT IN MICR RANGE …. NOT DOSE

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6
Q

bioavailibility

A

drug that reaches circulation (%)

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7
Q

clearence

A

vol of fluid removed per unit of time

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8
Q

volume of distribution

A

high protein binding drugs have LOWER VD . The more lipophilic, the HIGHER THE VD

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9
Q

steady state

A

imp for MIC to AUC ratio & fraction of time

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10
Q

therapeutic index

A

range between minimum effective conc to mimumum toxic conc

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11
Q

factors effecting host

A

age (extremeties)
renal/liver function
co-morbidities
polypharmacy
allergy
conditions (Myasthesia gravis, G6PD)

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12
Q

drugs to avoid in myasthesia gravis

A

drugs impair Neuromuscular junction transmission

result: increase of weakness

Aminoglycosides
fluroquininolones
tetracyclines
clindamycin
sulfonamides
macrolides
ampicillin

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13
Q

antimicrobial drugs have adverse reactions, name them

A
  • allergic reactions
  • toxic effects - at high
    dose
  • bioflor suppression - allowing growth ex: clostridium difficile
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14
Q

staining techniques

A

provide contrast by using dyes

smear –> air dye –> heat fix

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15
Q

types of dye used in staining techniques

A
  • basic - cationic chromaphore
  • acidic - anionic chromophore - negative staining
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16
Q

3 types of staining techniques

A
  1. simple
  2. differencial
  3. special
17
Q

acid fast stain - test for microbacterial cell walls

A

cells retaining basic stain in acid-alcohol

18
Q

What are the characteristic factors of an antibiotic

A

selective toxicity -
- target bacteria while causing NO OR MINIMAL HARM to patient

Therapeutic index -
- ratio between TOXIC and therapeutic

antimicrobial action -
Bacteriostatic: prevents further bacterial growth
- bacteriocidal - kills bacteria

activity spectrum
- broad - target gram +ve & -ve
- narrow - gram -ve or gram +ve ONLY

ADME -
- BBB - blood brain barrier antibiotics (cephalosporins, doxycycline)

  • unstable in acid
  • half life duration
19
Q

explain selective toxicity in antibiotics

A

they target bacteria

BUT
cause NO or minimal harm to patient

20
Q

types of antibiotic

A

broad - gram +ve/-ve
narrow - only gram +ve OR -ve
bacteriocidal - kills
bacreriostatic - suppress growth
gram postitive
- thick peptidoglycan
- porous (lets in easy)
- CRYSTAL VIOLET gram stain absorbed into peptidoglycan

gram negative
- THIN peptidoglycan
- have 2nd outer membrane
- outer layer not allow crystal violet to reach peptiodglycan - Pink counterstain

21
Q

Gram +ve vs Gram -ve

A

-ve –> outer membrane makes it harder for antibiotics to cross

+ve –> greater access to antibiotics –> more easy penetration + interaction with peptidoglycan

22
Q

Bactericidal antibiotics

A

kill the bacteria

23
Q

what do antibiotics target to kill bacteria?

A
  • cell wall synthesis (structure & arrangment of peptidoglycan)
  • protein synthesis
  • nucleic acid synthesis
  • metabolic reactions
  • membrane function
24
Q

what is peptidoglycan

A

backbone of carbohydrate units with sets of amino acid residues attached

25
Q

IMP Class 1 - Beta lactam antibiotics.

how do they interfere with bacteria ? Can you name some examples?

A

interfere with or prevent formation of peptidoglycan cross- links by enzyme inhibition
(antibiotics bind to penecillin-binding proteins)

ex:
- penecillin
- cephalosporin
- monobactamas
- carabpenms

  • cillin, -sporin, - bactams, -penems
26
Q

mechanism of action of beta lactam antibiotics

A

Beta lactam ring joins to the PHB (penecillin binding protein)’s amino terminus.

structural change opens up beta lactam ring

bind irreversibly to PBP

inhibits transpeptidase activity

= no cross linking of peptidoglycan chains in cell wall –> weak wall

cell lysis by lack of osmotic control = bursting

27
Q

how do beta lactam targeted bacteria gain antibiotic resistance

A

they disrupt interaction between beta lactam antibiotics and penecillin bindung protein = resistance

penecillinase/β-lactamase is an enzyme secreted that DESTROYS NATURAL PENECILLINS –> released as DEFENSE MECHANISM AGAINST PENECILLIN

28
Q

Are there any other antibiotic classes that inhibit cell wall synthesis ?

A

glycopeptides like vancomycin and teicopanin BUT BY DIFFERENT MECHANISM = SAME OUTCOME

29
Q

What are extended-spectrum penecillins? Can you name an example?

A

have broader spectrum of activity against many bacteria. EX: AMOXICILLIN

30
Q

Carboxypenecillins (carbenicillin, titracillin) & Ureidopenecillins (piperacillin, azlocillin, mezlocillin)

A

WIDER range and are effective against PSEUDOMONAS AERUGINOSA

31
Q

how do we reduce probability of antibiotic resistance in treatment regimens? Can you provide examples

A

combining penicillin + beta lactamase INHIBITOR (prevent destruction of penecillin)

Ex: Piperacillin-tazobactam & amoxicillin-clavulanic acid

32
Q

Clinical pharmacokinetics of Penciillins - what are the characteristics that influence the way they work in body? (are they hydrophobic/hydrophilic and what organ processes the drug?)

A
  • hydrophilic - do not cross blood brain barrier unless meninges inflammed –> effective in meningitis
  • excreted by kidneys uncharged - dose reduced in renal failure
33
Q

examples of penecililins

A

flucolaxcillin (acid stable, oral or non oral)
BETA LACTAMASE RESISTANCE
narrow spectrum for MSSA infections (staphylococcus aureus)

34
Q
A

cph 1902 (3 decks)

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