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Pharm Test 3 > Protein Synthesis Inhibitors III- Macrolides, Ketolides, Streptogramins, Lincosamides > Flashcards

Protein Synthesis Inhibitors III- Macrolides, Ketolides, Streptogramins, Lincosamides Flashcards

1
Q

Macrolides

A

ERYTHROMYCIN (older, not as good)
CLARITHROMYCIN
AZITHROMYCIN

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2
Q

Macrolides Mech of Action

A

Reversibly binds 50S ribosomal subunit

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3
Q

Macrolides- Bactericidal or Bacteriostatic?

A

Bacteriostatic, but may be bactericidal when present at high concentrations against very susceptible organisms
Erythro & clarithro= time-dependent
Azithro= concentration-dependent

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4
Q

Mechanisms of Resistance against Macrolide Abx

A

ACTIVE EFFLUX (primary resistance in U.S.)
ALTERED TARGET SITES (primary resistance in Europe)
CROSS-RESISTANCE OCCURS BETWEEN ALL MACROLIDES

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5
Q

Macrolides Spectrum of Activity Gram (+) Aerobes

A

Erythro & clarithro have best activity (Clarithro>Erythro>Azithro)

STAPH AUREUS (MSSA)
STREP PNEUMO
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6
Q

Macrolides Spectrum of Activity Gram (-) Aerobes

A

Azithro>Clarithro>Erythro

H. influenze (not erythro)
M. catarrhalis
Neisseria spp.
does not have activity aginst any enterobacteriaceae

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7
Q

Macrolides Spectrum of Activity Anaerobes and Other bacteria

A

Anaerobes: activity against upper airway anaerobes

Other: many

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8
Q

Macrolides Spectrum of Activity Atypical Bacteria

A

all macrolides have EXCELLENT activity against atypical bacteria including:
LEGIONELLA PNEUMOPHILA- DOC
CHLAMDOPHILA (PSITTACOSIS) AND CHLAMYDIA SPP.
MYCOPLASMA SPP.
UREAPLASMA UREALYTICUM

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9
Q

Macrolides- Erythromycin Absorption

A

variable (F= 15-45%)
food may decrease absorption
base- destroyed by gastric acid; enteric coated
esters and ester salts- more acid stable

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10
Q

Macrolides- Clarithromycin Absorption

A

well-absorbed and acid stable (F=55%), regardless of presence of food

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11
Q

Macrolides- Azithromycin Absorption

A

Acid stable, F= 37% regardless of presence of food

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12
Q

Macrolides Distribution

A

extensive

MINIMAL CSF PENETRATION

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13
Q

Macrolides Elimination

A

ERYTHRO- EXCRETED IN BILE AND METABOLIZED (CYP450)
CLARITHRO- METABOLIZED/ELIMINATED BY KIDNEY
AZITHRO- ELIMINATED BY BILIARY EXCRETION

NONE OF THE MACROLIDES ARE REMOVED DURING HEMODIALYSIS!!

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14
Q

Macrolides Clinical Uses

A 
CA-PNEUMONIA- MONOTHERAPY FOR OUTPATIENTS; WITH CEFTRIAXONE FOR INPATIENTS
WITH CEFTRIAXONE FOR CA-BACTERIAL PNEUMONIA FOR "ANTI-INFLAMMATORY EFFECT)
ALTERNATIVE FOR PEN-ALLERGIC PATIENTS:
- Group A Strep URIs
- prophylaxis of bacterial endocarditis
- syph and GC
- rheumatic fever prophylaxis
- Strep sp. and S. pneumo resistant
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15
Q

Macrolides Drug Interactions

A 
ERYTHROMYCIN & CLARITHROMYCIN ONLY!! Are inhibitors of p450 system and can increase concentrations of:
THEOPHYLLINE
CARBAMAZEPINE
CYCLOSPORINE
PHENYTOIN
WARFARIN
DIGOXIN
VALPROIC ACID
others

NOT AZITHROMYCIN!!!

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16
Q

Ketolides

A

TELITHROMYCIN

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17
Q

Ketolides/Telithromycin Mech of Action

A

bind to two domains (II & V) on 50S ribosomal subunit; binds 10x more strongly to domain II than macrolides

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18
Q

Ketolides/Telithromycin- Bactericidal or Bacteriostatic?

A

Bacteriostatic

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19
Q

Mechanism of Resistance against Ketolides/Telithromycin

A

ribosomal binding site alterations

20
Q

Ketolides/Telithromycin Spectrum of Activity

A

MACROLIDE-RESISTANT Streptococcus and Staphylococcus

poor activity against H. influenzae

21
Q

Ketolides/Telithromycin ABSORPTION

A

F= 57%

unaffected by food

22
Q

Ketolides/Telithromycin DISTRIBUTION

A

excellent into tissues and cells

protein binding= 60-70%

23
Q

Ketolides/Telithromycin ELIMINATION

A

metabolized by cytochrome p450 (3A4); 1/2 life= 10 hours

no dose adjustment in renal insufficiency

24
Q

Ketolides/Telithromycin Adverse Effects

A 
Use has been limited
DIARRHEA
HEPATOTOXICITY
DECREASED VISUAL ACUITY
BLURRED VISION
QTc prolongation
25
Q

Ketolides/Telithromycin Drug Interactions

A

INHIBITOR OF CYTOCHROME P450 3A4

- similar drug interactions as erythro and clarithro (digoxin, phnytoin, warfarin, cyclosporin)

26
Q

Ketolides/Telithromycin Clinical Uses

A

COMMUNITY-ACQUIRED PNEUMONIA
acute bacterial sinusitis
acute exacerbations of chronic bronchitis

27
Q

Streptogramins

A

Developed in response to need for abx w/ activity against resistan Gram (+) bacteria, namely VRE
Synercid is the first available; is a combination of two semi-synthetic pristinamycin derivatives in a 30:70 ratio: QUINUPRISTIN:DALFOPRISTIN

28
Q

Streptogramins/Synercid MECH OF ACTION

A
  • each agent acts individually on 50S ribosomal subunits to inhibit early and late stages of protein synthesis
  • binds 50S ribosome near where the macrolides and clindamycin bind
29
Q

Streptogramins/Synercid- Bactericidal or Bacteriostatic?

A

Bacteriostatic, may be time-dependent bactericidal against some bacteria

PAE exists for Gram (+)

30
Q

MECHANISMS OF RESISTANCE against Streptogramins/Synercid

A

alterations in ribosomal binding sites (erm)

enzymatic inactivation

31
Q

Streptogramins/Synercid Spectrum of Activity

A

Gram (+):
MRSA AND MSSA
PRSP
ENTEROCOCCUS FAECIUM (INCLUDING VRE)

Gram (-): not used
Atypical Bacterial: not used

32
Q

Streptogramins/Synercid Absorption

A

only available parenterally

33
Q

Streptogramins/Synercid Distribution

A

MINIMAL CSF PENETRATION

penetrates into extravascular tissue, lun, skin/soft tissue

34
Q

Streptogramins/Synercid Elimination

A

both agents are metabolized

35
Q

Streptogramins/Synercid Clinical Uses

A 
VRE (FAECIUM) BACTEREMIA
very expensive ($350/day)
36
Q

Streptogramins/Synercid Drug Interactions

A 
CYTOCHROME P450 INHIBITOR, thus
Antihistamines
Cholesterol-lowering agents
immunosuppressive agents
Calcium channel blockers
others
37
Q

Streptogramins/Synercid Adverse Effects

A

VENOUS IRRITATION

MYALGIAS, ARTHRALGIAS

38
Q

Clindamycin

A

Semisynthetic derivative of lincomycin, but is absorbed better and has a broader spectrum of activity

39
Q

Clindamycin Mech of Action

A

Binds exclusively to 50S ribosomal subunit

- binds in close proximity to macrolides and Synercid, may cause competitive inhibition

40
Q

Clindamycin- Bactericidal or Bacteriostatic?

A

Bacteriostatic, but can be bactericidal when present at high concentrations against very susceptible organisms

41
Q

Mechanisms of Resistance against Clindamycin

A

ALTERED TARGET SITES

ACTIVE EFFLUX- mef gene encodes an efflux pump that pumps macrolides out of the cell BUT NOT CLINDAMYCIN;

42
Q

Clindamycin Spectrum of Activity

A

Gram (+):
MSSA
CA-MRSA

Anaerobes: best activity against Above the Diaphragm Anaerobes
BACTEROIDES SPP
some Clostridium spp. (NOT C-DIF)

43
Q

Clindamycin Absorption

A

IV or PO
rapidly and completely absorbed
food has minimal effect

44
Q

Clindamycin Distribution

A

BONE

MINIMAL CSF PENETRATION

45
Q

Clindamycin Elimination

A

metabolized by liver

NOT REMOVED DURING HEMODIALYSIS

46
Q

Clindamycin Clinical Uses

A

ANAEROBIC INFECTIONS OUTSIDE THE CNS (PULMONARY, OTHERS)
SKIN & SOFT TISSUE INFECTIONS
- PEN-ALLERGIC PATIENTS
- PTS W/ INFECTIONS DUE TO CA-MRSA

47
Q

Clindamycin Adverse Effects

A

C-DIF COLITIS
Hepatotoxicity- rare
Allergy- rare
Gastrointestinal

Pharm Test 3 (10 decks)

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