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OPath Block 2 > 8. Principles of Chemotherapy > Flashcards

8. Principles of Chemotherapy Flashcards

1
Q

What is chemotherapy for infectious diseases?

A

Use of synthetic, semi-synthetic and naturally occuring chemicals that selectively inhibit specific organisms causing infectious diseases

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2
Q

Chemotherapy of infecitous diseases generally depends on _________?

A

Selective toxicity

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3
Q

What are the 4 mechanisms of chemotherapy action?

A
  1. Antimetabolites
  2. Inhibitors of cell wall synthesis
  3. Inhibitors of protein synthesis
  4. Inhibitors of nucleic acid synthesis
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4
Q

How do antimetabolites work?

A

Compete with substrate for binding to specific enzymes involved in given metabolic pathway

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5
Q

What is the significance of inhibitors of cell wall synthesis ?

A

Human cells do not have cell walls like bacteria and fungi.

Allows for very specific targeting for chemotherapy

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6
Q

What is the mechanism of inhibitors of protein synthesis?

A

Inhibited protein synthesis slows cellular growth.

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7
Q

Inhibitors of nucleic acid synthesis are often used in treating what kinds of condition?

A

Cancer

Viral infection

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8
Q

What are key laboratory methods in diagnosing infections?

A
  1. Gram stain
  2. Disk diffusion
  3. Empiric Therapy
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9
Q

What is disk diffusion laboratory diagnosis?

A

Grow microorganism on plate with several disks of different antibiotics.

Shows which antibiotics are effective against the microorganism

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10
Q

What is empiric therapy?

A

Initiation of treatment prior to determination of a firm diagnosis.

Used in emergency situation

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11
Q

What are 3 key features of Gram + bacteria?

A

Thick layer of murein (peptidoglycan)

Hydrophilic molecules can readil diffuse

Retain Stain

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12
Q

What are 3 key features of Gram - bacteria?

A

Thin layer of murein (peptidoglcan)

Passage of hydrophilic molecules hindered

Lose stain

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13
Q

What is susceptibility?

A

Minimum concentration (MIC) of antibiotic to inhibit growth of organism in vitro

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14
Q

The concentration of antibiotic in the blood should exceed the MIC by how much to ensure successful treatment?

A

Exceed by a factor of 2 - 4 fold

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15
Q

What is a narrow spectrum chemtherapeutic?

A

A chemotherapeutic agent acting only on a single or limited group of microorganisms

i.e. isoniazid

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16
Q

What is an extended spectrum chemotherpeutic?

A

Agents that are effective against gram + and a singificant number of gram - bacteria

i.e. Ampicillin

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17
Q

What is a broad spectrum chemotherapeutic?

A

Agent that affects wide variety of microorganisms

i.e. tetracylcline and chloramphenicol

18
Q

What is a therapeutic index?

A

An index used to assess the safety of a drug.

TI = TD50/ED50

19
Q

How does a wide therapeutic index drug’s dynamic differ from a narrow therapeutic index drug’s dynamic?

A

A wide TI drug has a wide range of doses it can give while still being safe. There is a large gap between the effective dose and toxic dose.

A narrow TI drug has a narrow range of doses it can give while still being safe. There is a narrow gap between the effective dose and toxic dose.

Wide TI drug is safer than narrow TI drug

20
Q

What precaution must be taken when administering a narrow TI drug?

A

Check peak and blood levels 30 misn before and after drug administration

21
Q

Define bacteriostatic drug

A

Bacteriostatic drugs arrest growth and replication of bacteria at serum levels achievable in patient.

Leave viable organisms to begin second cycle

22
Q

What do bacteriostatic drugs tend to target in bacteria?

A

Target metabolic pathways that are necessary for bacterial growth but not survival.

Inhibitors of protein synthesis and antimetabolites

23
Q

Define bactericidal drugs

A

Drugs that kill bacteria.

24
Q

What conditions indicate the use of bactericidal drugs rather than bacteriostatic drugs?

A

Septicemia or serious infection in patients with impaired host defense

25
Q

What to bactericidal drugs tend to target in bacteria?

A

Target metabolic pathways essential for bacterial survival

Cell wall synthesis inhibitors

Inhibitors of nucleic acid synthesis

26
Q

What is the only inhibitor of protein synthesis that is bactericidal?

A

Aminoglycosides

27
Q

Penicillin uses what mechanism of chemotherapy action?

A

Inhibitor of cell wall synthesis

28
Q

Cephalosporin uses what mechanism of chemotherapy action?

A

Cell wall synthesis

29
Q

What are the 4 bacteriostatic inhibitors of protein synthesis antibiotics?

A

Chloramphenicol

Clindamycin

Macrolides-erythromycin

Tetracycline

30
Q

What are 2 bacteriostatic antimetabolite antibiotics?

A

Sulfonamide

Trimethoprim

31
Q

When do we use a combinatoin of antimicrobial drugs?

A

Against organisms resistant to single drug therapy

Severe infection of uncertain etiology or polymicrobial infection

32
Q

What 3 bacteria are resistant to single drug therapy?

A

Pseudomonas

Group D streptococci

Tuberculosis

33
Q

What are 4 adverse effecs of antibiotic therapy?

A

Drug-drug interactions

Allergic reactions

Superinfections

GI disturbances

34
Q

Two or more drugs administered in therapeutic dosages at hte same time or in close sequence has what 3 possible outcomes (drug to drug interactions)?

A
  1. May act independetly
  2. May interact to increase or decrease the magnitude or duration of action of one or more drugs
  3. May interact to cause an unexpeceted reaction
35
Q

What kinds of antibiotic allergic reactions can occur?

A

Substantial morbidity and mortality

T cell mediated delayed hypersensitivity

IgE mediated immediate hypersensitivity

Cross allergy between beta-lactam antibacterial agents

36
Q

What are someclassic GI disturbances from antibiotics?

A

Nausea, retching, vomiting

Diarrhea

Abdominal cramping

Pseudomembranous colitis

37
Q

What are the mechanisms of drug resistance?

A

Treatment with an antibacterial agent affects resistance patterns:

  1. Genetic mutation causes resistance
  2. Gene transfer facilitates the spread of resistance
38
Q

How do you decrease drug resistance?

A
  1. Only use when there is a well established need for antibiotics
  2. Select based on susceptibility tests
  3. Adequate doses for adequate duration
39
Q

What is antibacterial prophylaxis?

A

Administration of a single effective drug to PREVENT infection by a specific organism or to eradicate it soon after it has been established

40
Q

What are the two purposes of antibacterial prophylaxis?

A

To protect healthy persons from infection by a specific microorganism to which they have been exposed

To prevent secondary bacterial infection in patients who are ill with other diseases

41
Q

When must we do SBE (subacute bacterial endocarditis) prophylaxis?

A

All dental procedures that involve manipulation of gingival tissue or PA region of teeth or perforation of oral mucosa in patients that have reaosnable risk of endocaditis

OPath Block 2 (10 decks)

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