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Pharmacy Year 2 TBL 1 > Antimicrobials - Antibiotics, antivirals, antifungals > Flashcards

Antimicrobials - Antibiotics, antivirals, antifungals Flashcards

1
Q

What are antibiotics?

A

Naturally produced antimicrobial agents

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2
Q

What percentage of antibiotics are clinically useful?

A

Less than 1%

but these can be synthetically altered to increase efficacy

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3
Q

What kind of drugs do Beta-lactam antibiotics comprise?

A

Penicillins
Cephalosporins
Cephamycins

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4
Q

Penicillins and Cephalosporins comprise what percentage of antibiotic production?

A

Over 50%

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5
Q

What fungus produces penicillin

A

Penicillin chrysogenum

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6
Q

What is the beta-lactam method of action?

A

Potent inhibitors of cell wall synthesis
The transpeptidation (cross-linking) action is essential to cell wall synthesis
Transpeptidases can also bind to the beta-lactam ring (penicillin-binding proteins/PBPs)
The cell wall is still formed but with no cross links
It therefore becomes weak
Osmosis differences result in cell lysis

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7
Q

Describe Cephalosporins structure

A

6 membered dihydrothiazine ring (penicillin has 5)

Semi-synthetic

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8
Q

Cephalosporin method of action?

A

Same as penicillin

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9
Q

Advantage of cephalosporins over penicillins?

A

More resistant to beta-lactamase enzymes

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10
Q

Example of a Cephalosporin antibiotic?

A

Ceftriaxone used to treat Neisseria infections

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11
Q

Describe the structure of aminoglycosides

A

Contain amino sugars bound via glycosidic bonding to each other

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12
Q

Give 4 examples of aminoglycosides

A

Streptomycin, kanamycin, neomycin, gentamicin

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13
Q

How do aminoglycosides work?

A

Inhibit protein synthesis at the 30S subunit of the ribosome

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14
Q

Aminoglycosides are active against what type of bacteria?

A

Gram negatives

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15
Q

What is the frequency of use of aminoglycosides like now?

A

declined and superseded by semi-synthetic penicillins e.g. ampicillin, oxacillin, methacillin

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16
Q

First broad spectrum antibiotic class?

A

Tetracyclines

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17
Q

Basic structure of tetracyclines?

A

naphthecene ring system

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18
Q

How do tetracyclines work?

A

Interferes with 30S ribosome subunit function

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19
Q

Wide use of tetracyclines in what area of medicine?

A

Veterinary

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20
Q

What are growth factors?

A

Growth factors are specific substances required by microbes because they cannot synthesise them

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21
Q

What are growth factor analogues?

A

Blocker of the utilisation of growth factors
synthetic compounds
structurally similar to growth factor but cannot duplicate their function within the cell

22
Q

Give an example of a sulfa drug

A

Sulfanilamide

23
Q

What is sulfanilamide

A

a growth factor analogue that is an analogue of p-aminobenzoic acid (PABA); a component of folic acid

24
Q

What process does sulfanilamide block?

A

The production of folic acid

25
Q

Where do bacteria get their folic acid from? What about eukaryotes?

A

Bacteria produce their own

Eukaryotes get it from their diet

26
Q

Name a growth factor analogue that is effective only against mycobacterium

A

Isoniazid

interferes with synthesis of mycolic acid

27
Q

How have nucleic acid base analogues been formed?

A

With the addition of bromine or flourine to an existing growth factor analogue

28
Q

What are quinolones? What do they do?

A

antibacterial compounds that interfere with DNA gyrase

29
Q

Give an example of a quinolone

A

ciprofloxacin

30
Q

What do antiviral drugs target?

A

Host structures, so generally are quite toxic

31
Q

Name the group of most successful and commonly used antivirals

A

nucleoside analogues

32
Q

Give an example of a nucleoside analogue antiviral drug

A

AZT

33
Q

How do nucleoside analogue antiviral drugs work?

A

Block reverse transcriptase and hence production of viral DNA

34
Q

Another name for nucleoside analogues?

A

Nucleoside reverse transcriptase inhibitors

35
Q

How do nonnucleoside transcriptaste inhibitors (NNRTIs) work?

A

Bind directly to reverse transcriptase and inhibit reverse transcription

36
Q

Name 3 classes of antiviral drug (excluding nucleoside analogues)

A
  • Protease inhibitors
  • Fusion inhibitors
  • Interferons
37
Q

Name 2 categories of drug that limit influenza infection successfully

A

Adamantanes

Neuraminidase inhibitors

38
Q

How do protease inhibitor antivirals work?

A

inhibit the processing of large viral proteins into individual components

39
Q

How do fusion inhibitors work?

A

prevent viruses from successfully fusing with the host cell

40
Q

What are interferons and how do they work?

A

They are small proteins that prevent viral multiplication by stimulating antiviral proteins in uninfected cells

41
Q

Why do fungi pose special problems for chemotherapy?

A

Because they are eukaryotic

as a result, many antifungals are topical

42
Q

Name 7 things antifungal drugs can possibly target

A
  • Membrane function
  • cell wall synthesis
  • ergosterol synthesis
  • nucleic acid synthesis
  • microtuble formation
  • folate synthesis
  • chitin synthesis
43
Q

How do antifungal drugs target membrane function?

A

Polyenes can bind to ergosterol and disrupt membrane integrity

44
Q

How do antifungal drugs target cell wall synthesis?

A

Polyoxins inhibit chitin synthesis
Echinocandins inhibit glucan synthesis
Echinocandins do this by inhibiting 1,3-beta-delta glucan synthase

45
Q

What antifungal drugs target ergosterol synthesis?

A

Azoles and allylamines inhibit it

46
Q

How do antifungal drugs target nucleic acid synthesis?

A

5-flourocytosine is a nucelotide analogue that inhibits nucleic acid synthesis

47
Q

How do antifungal drugs target microtuble formation?

A

Griseofulvin disrupts microtuble aggregation during mitosis

48
Q

Name a treatment for a Candida (fungal) infection

A

Echinocandins

49
Q

Name the most successful example of computer-aided drug design for antimicrobials

A

Saquinavir

Binds to active site of HIV protease

50
Q

What led to the discovery of platensimycin?

A

New methods of screening natural compounds

computer aided drug design etc.

Pharmacy Year 2 TBL 1 (13 decks)

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