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Pharmacology > Antibiotics (Exam 2) > Flashcards

Antibiotics (Exam 2) Flashcards

1
Q

Define Bacteriostatic

A

antibiotic INHIBITS bacterial growth

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2
Q

Define Bactericidal

A

antibiotic has the ability to KILL bacteria

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3
Q

What is a narrow spectrum antibiotic?

A

-Antibiotics that are only effective against a SMALL number of bacteria.

Example: Penicillin = effective against gram (+) & a few gram (-) bacteria

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4
Q

What is a broad spectrum antibiotic?

A

Effective against MANY bacteria.

Example: Tetracycline = antibiotic w/ widest spectrum of kill = gram (+) & gram (-) bacteria, rickettsia & some viruses

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5
Q

What is the normal micro-floras that populate a healthy individuals oral cavity?

A

-Predominant microbe of the oral cavity is gram (+) strep or staph (90-95%)

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6
Q

Which organisms make up oral infections?

A

1) ALL oral/facial infections occur from resident microorganisms which are already in mouth
2) “outside” organisms causing oral infections must be introduced to oral cavity = e.g. trauma
3) Without even taking a culture, we know oral infection is most likely a gram (+) strep or staph

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7
Q

What is the drug of choice for the treatment of orofacial infections?

A
  • Penicillin is drug of choice

* PENICILLIN V is the best choice for orofacial infections

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8
Q

How is Penicillins eliminated in the body? (main routes).

A
  • Penicillin molecule excreted unchanged & very rapidly!
  • 10% via glomerular filtration (passive transfer)
  • 90% via tubular secretion (active transport)
  • 70% of an oral dose of penicillin is excreted within the first 4 hours
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9
Q

Explain the rationale for pretreating patients w/ PROBENECID prior to administration of penicillin.

A

1) Probenecid (benemid) = a medication used to treat gout
2) STOPS reabsorption of uric acid back into the bloodstream
3) Also excreted by ACTIVE TRANSPORT
4) Competes w/ penicillin molecule for the active transport mechanism
5) Has greater affinity for the carrier than penicillin does
6) If probenecid is given before penicillin is given, penicillin is NOT excreted as rapidly
7) ELEVATES blood level of penicillin 3-4 times; PROLONGS effect of penicillin

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10
Q

What is Penicilinase?

A

A beta lactamase (enzyme) that breaks down the beta lactam ring of the penicillin molecule

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11
Q

With respect to absorption from the GI tract, bacterial spectra, & susceptibility to beta-lactamase, which penicillin is the best match for the following ?

1) Bactericidal
2) Narrow spectrum
3) Acid-labile = broken down by gastric acid, 70-80% destroyed by gastric acid
4) Penicillinase-labile = broken down by penicillinase-producing microorganisms

A

Penicillin G

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12
Q

Describe the characteristics of Penicillin G, with respect to absorption from the GI tract, bacterial spectra, & susceptibility to beta-lactamase.

A

1) Penicillin G = bond penicillin molecule to PROCAINE molecule
2) Repository form, dissolved in oil, given IM
3) NARROW spectrum
4) Given IM, no GI absorption
5) Penicillinase-labile = broken down by penicillinase-producing microorganisms

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13
Q

Describe the characteristics of Benzathine Penicillin G, w/ respect to absorption from the GI tract, bacterial spectra, & susceptibility to beta-lactamase.

A

1) Penicillin G bonded w/ benzathine molecule, repository form, dissolved in oil
2) NARROW spectrum
3) Given IM after dose of aqueous penicillin, longest lasting, no GI absorption
4) Persists in plasma for 3 weeks
5) Penicillinase-labile = broken down by penicillinase-producing microorganisms

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14
Q

Describe the characteristics of Penicillin V, w/ respect to absorption from the GI tract, bacterial spectra, & susceptibility to beta-lactamase.

A

1) Sodium penicillin V= improved version of penicillin G b/c it’s ACID stabile
2) Taken ORALLY, not broken down by gastric acid
3) Better bioavailability when given in POTASSIUM salt form
4) NARROW spectrum
5) Penicillinase-labile = broken down by penicillinase-producing microorganisms

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15
Q
  • What are examples of the Penicillinase resistant drugs?

- What are they used for?

A

1) Cloxacillin (canadian drug)
2) Dicloxacillin (canadian drug)
3) Piperacillin and tazobactam sodium
4) Ticarcillin and clavulanate potassium
- Only used for infections w/ penicillinase producing bacteria

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16
Q

With respect to absorption from the GI tract, bacterial spectra, & susceptibility to beta-lactamase, which penicillin is the best match?

1) BacteriCIDAL, BROAD spectrum
2) ACID stable
3) Penicillinase-labile = broken down by penicillinase-producing microorganisms

A

-Ampicillin

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17
Q

Principen with Probenecid

is a ___________spectrum

A

Broad

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18
Q

Which antibiotic is:

1) Broad spectrum
2) Penicillinase-labile = broken down by penicillinase-producing microorganisms

A

Amoxicillin (Amoxil)

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19
Q

Which antibiotic is:
1) Clavulanic acid added to amoxicillin

2) Broad spectrum
3) Synthetic = inhibits the penicillinase enzyme (beta lactamase)

A

Augmentin

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20
Q

What are the MOST common adverse effects of penicillin?

A

1) Oral candidiasis, black hairy tongue
2) Maculopapular rash due to toxicity to amoxicillin
3) Diarrhea due to augmentin
4) Allergy to penicillin

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21
Q

Name two types of repository penicillin.

A

1) Procaine Penicillin G = repository form

2) Benzathine Penicillin G = repository form

22
Q

What is the mechanism of action of penicillin?

A

1) Bactericidal
2) Blocks bacterial cell wall synthesis by interfering with structural glycopeptides
3) Bacterial cell death results from lysis

23
Q

Detail penicillins w/ regard to bacterial spectra, toxicity, mechanism of action, & absorption from GI tract.

A

1) Bacterial spectra: narrow or broad depending on type
2) Toxicity: Oral candidiasis, black hairy tongue, maculopapular rash due to toxicity to amoxicillin, diarrhea due to augmentin, allergy to penicillin
3) Mechanism of action: Bactericidal. Blocks bacterial cell wall synthesis by interfering w/ structural glycopeptides. Bacterial cell death results from lysis.
4) Absorption: Acid liable. Oral: natural penicillins (penicillin G) is incomplete & variable due to destruction by gastric juices (given parenterally). Semi-synthetic (penicillin V) is more acid stable, therefore more uniform absorption.

24
Q

Detail cephalosporins w/ regard to bacterial spectra, toxicity, mechanism of action, & absorption from GI tract.

A

1) Generations designate extent of antimicrobial action 1st generation = narrower than second. The HIGHER the generation, the MORE broad spectrum of kill.
2) Toxicity reactions: anaphylaxis, fever, rash (erythema multiforme), eosinophilia, GI upset, glossitis, stomatitis, candididis, nephrotoxicity
3) Patients intolerant to penicillins may be intolerant to cephalosporins
4) Mechanism of action: INHIBIT bacterial cell wall synthesis similar to penicillin. Results in defective cell walls & cells become osmotically unstable causing lysis. RAPIDLY dividing bacteria are MOST susceptible. Bactericidal.
5) Absorption: Acid stable. MOST absorbed well through GI tract, may be delayed by food in stomach.

25
Q

What is the first generations of cephalosporins used in dentistry?

A

1) Cephalexin (KEFLEX)* know this one
2) Cefadroxil (duricef) *know this one
3) Cephradine (velosef) *know this one

26
Q

What is the second generations of cephalosporins used in dentistry?

A

1) Cefaclor (raniclor)

27
Q

Name the most frequently observed adverse effect of the macrolide antibiotics: (erythromycin, azithromycin, clarithromycin).

A

Gastrointestinal Side Effects:

1) Stomach pain
2) Nausea/vomiting
3) Cramping
4) Diarrhea

Other:

5) Cholestatic jaundice (hepatitis)
6) Allergic Reactions
7) Fever
8) Eosinophilia
9) Skin eruptions

28
Q

What is mechanism of action of erythromycin?

A

1) Bacteriostatic.
Bactericidal at HIGH doses or when used against highly susceptible organisms

2) ONLY effective against ACTIVELY DIVIDING organisms
3) INHIBITS protein synthesis by binding to 50S ribosomal subunits of sensitive microorganisms.
4) BINDS to ribosome at a site near peptidyltransferase to inhibit peptide bond formation.
5) SUPPRESSES bacterial growth due to the lack of protein production.

29
Q

What are the absorption patterns of erythromycin?

A

Absorption:
1) Absorbed from upper part of intestine.

2) Food reduces absorption.
3) Effectiveness is dependent upon particular derivative, dosage form, acid stability of the derivative & gastric emptying time
4) Unknown as to whether drug is absorbed to any substantial extent when applied topically to mucous membranes

30
Q

What are the distribution patterns of erythromycin?

A

1) Diffuses readily into tissues
2) Crosses placenta
3) Distributed to most body tissues

31
Q

What are the excretion patterns of erythromycin?

A

1) Absorbed from the stomach to the liver
2) Metabolized by the liver & excreted into the bile
3) As it goes thru bile duct, causes smooth muscle to constrict, causing bile to back up into liver resulting in cholestatic hepatitis a potentially fatal condition
4) Urine
5) Feces (primarily) = Large size of the molecule causes it to be excreted here

32
Q

What are two alternative macrolide antibiotics used for antibiotic premedication in dentistry?

A

1) Clarithromycin (Biaxin)

2) Azithromycin (Zithromax)

33
Q

Describe the mechanism of action of clindamycin.

A

1) Similar to erythromycin. Antibacterial

2) Interferes w/ bacterial protein synthesis & inhibits peptide bond formation

34
Q

What are indications for the use of clindamycin?

A

1) Infections caused by anaerobic organisms
2) Orofacial infections & periodontal infections caused by anaerobic bacteria
3) Anaerobic osteomyelitis (good for oral bone infections b/c drug penetrate bone)
4) Drug of choice for orofacial infections in penicillin allergic patients
5) Used for endo infections, as in mature endodontic infections, Bacteroides are prevalent & particularly susceptible to clindamycin.

35
Q

What are 2 classes of antibiotics that are MOST often associated w/ Clostridum difficule infections resulting in pseudomembraneous colitis?

A

1) Clindamycin
2) Cephalosporins

*may not appear until weeks/months after antibiotic exposure (80% = nosocomial)

  • Pseudomembranous colitis*
  • Super infection
  • Clindamycin causes diarrhea be/c resident bacteria of GI tract have been killed
36
Q

What is the influence of divalent cations on TETRACYCLINE absorption from the GI tract?

A

1) 4 (tetra) ring structure w/ a lot of OH & O groups = reason why these drugs chelate cations
2) Chelate divalent cations (Ca, Mg, Fe, Al) = reason why can’t have dairy, iron or antacids w/ this drug

37
Q

What is the route of administration for tetracyclines that might indicate a contraindication in some patients?

A
  • Contraindicated in children w/ developing teeth/bone, pregnant patients
  • Incorporated in to teeth/bone thru chelation causing pitting & yellowing
38
Q

What is the hard tissue related adverse effects of tetracyclines during pregnancy & small children?

A

1) Crosses placenta, category D
2) Because of chelating effects, drug is incorporated into teeth and bone
3) Drug becomes permanent part of enamel as it calcifies, irreversible b/c enamel doesn’t remodel like bone
4) Teeth become yellow/gray color & fluoresce under black light
5) Binding to bone may result in depression of skeletal growth in growing children, may be partially reversible w/ bone remodeling

39
Q

What are three tetracycline preparations?

A

1) doxycycline *know this one
2) minocycline *know this one
3) tetracycline *know this one

40
Q

How does doxycycline hyalite differs from doxycycline?

A

-Doxycycline hyclate (Periostat) is a subantimicrobial dose that only inhibits collagenase but doesn’t kill bacteria

41
Q

What is an example of antibiotic antagonism using tetracyclines?

A

1) Tetracyclines are contraindicated w/ penicillin/amoxicillin
2) Tetracycline (static); penicillin (cidal)
3) If a patient is on a tetracycline an requires AHA antibiotic premedication, you have to use another static drug like Clindamycin

42
Q

What are the contraindications for the use of tetracyclines?

A

1) Pregnancy
2) Children
3) Patients taking penicillin/amoxicillin

43
Q

What are the major Medical and Dental indications for quinolines?

A

Medical:

1) Respiratory infections
2) Bronchitis, community-acquired pneumonia
3) Urinary tract infections

Dental:

1) Rarely used in dentistry
2) Used to treat periodontal disease when other agents are not effective

44
Q

What is the mechanism of action of quinolines?

A

1) Targets DNA topoisomerases
2) Blocks action of 2 bacterial topoisomerases — enzymes that relieve coils that form in DNA when helix is opened in preparation for replication, transcription, or repair.

45
Q
  1. Compare and contrast the quinolones with respect to bacterial spectra
A

1) Bactericidal

2) Broad spectrum

46
Q

Compare and contrast the quinolines with respect to their mechanism of action

A

1) Targets DNA topoisomerases
2) Blocks action of 2 bacterial topoisomerases — enzymes that relieve coils that form in DNA when helix is opened in preparation for replication, transcription, or repair.

47
Q

Compare and contrast the quinolines with respect to their toxicity and adverse effects (GI, CNS, & allergy).

A

Gastrointestinal:

  1. Nausea/vomiting
  2. Diarrhea
  3. Xerostomia

Central Nervous System:

  1. Headache
  2. Dizziness
  3. Vertigo/syncope

Allergy:

  1. Pruritus
  2. Urticaria
48
Q

What is the mechanism of action of metronidazole and its use in dentistry?

-What is it taken up by?
What is it non-enzymatically reduced by?
- As many as how many enzymes are affected?
-

A

1) Taken up by diffusion, is selectively absorbed by anaerobic bacteria & sensitive protozoa.
- Non-enzymatically reduced by reacting w/ reduced ferredoxin, (generated by pyruvate oxido-reductase)
- Many reduced intros intermediates form sulfonamides & thioether linkages w/ cysteine-bearing enzymes, deactivating enzymes.
- As many as 150 separate enzymes are affected.

2) Metronidazole metabolites are taken up into bacterial DNA, & form unstable molecules. This function only occurs when metronidazole is partially reduced, & b/c this happens only in anaerobic cells, it has relatively little effect upon human cells or aerobic bacteria.
3) Used to supplement other antibiotics when periodontal condition is not responding

49
Q

What are the common adverse oral side effects associated with antibiotics?

A

1) Candidiasis (black hairy tongue)
2) Stomatitis
3) Glossitis

50
Q

What are the drug interaction of oral contraceptives w/ antibiotics & recommend related strategies for patient education & compliance?

A

1) Hormones activated by gut flora: if DECREASED flora, DECREASED active hormone, possible ovulation
2) Site of drug interaction: small intestine
3) Use alternative birth control until next cycle

51
Q

What are the effects of antibiotics on warfarin (Coumadin)?

A

1) Patients on warfarin have hypoprothombinemia
2) Drug competes with vitamin K for synthesis of prothombin
3) Vitamin K synthesized by gut bacteria
4) Antimicrobials kill these bacteria, causing decreased levels of vitamin K
5) Warfarin then has no competitor, and causes excessive anticoagulation (very thin blood)
6) Quinolones

Pharmacology (13 decks)

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