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exam 1 drugs dpphuckt > Macro, Clinda, Quinu/Dalfo, Linezo > Flashcards

Macro, Clinda, Quinu/Dalfo, Linezo Flashcards

1
Q

what do macrolides include?

A

erythromycin, azithromyci, clarithromycin

the picture below sums up all of the drugs way of inhibiting protein synthesis

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2
Q

macrolides are characterized as bacteriocidal or bacteriostatic? What is their mechanism? List 2

A

bacteriostatic;

  1. bind reversibly to a site on the 50S subunit which causes the dissociation of the peptidyl tRNA from the ribosome.
  2. macrolides also inhibit the translocation step. Translocation is when there’s movement of the peptidyl tRNA from the acceptor site to the donor site allowing the next amino acid to come in. So macrolides interfere with this process so that you wind up with little sections of amino acids.
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3
Q

bacteria can become deficient to macrolides because of 3 reasons

A
  1. methylase enzyme. because of diminished affinity for the binding site on the 50S subunit due to methylation of an adenine nucleotide in the 23S rRNA.
  2. may also gain resistance to macrolides because there are changes in the ability of the drug to get into the cell. The resistant bacteria may also develop pumps that pump out the macrolide so fast that you can’t achieve adequate concentration of the drug inside the cell for effective antibacterial effects.
  3. have developed an esterase that can inactivate the macrolide and this can particularly be seen with erythromycin resistance.
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4
Q

what is the disadvantage in having resistance with macrolides?

A

it confers resistance to other drugs; i.e cross resistivity

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5
Q

what is the characteristic of the methylase enzyme that confers the resistance for the bacteria to the macrolide

A

it can be inducible or constitutive

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6
Q

the development of the esterase resistance seen in macrolides is present in which macrolide?

A

erythromycin

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7
Q

what is the preferred treatment of C. Trachomatis

A

single dose of 1 gram of Azithromycin

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8
Q

less active vs streptococci and staphylococci

A

azithromycin is less active than erythromycin

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9
Q

similar in its effect to erythromycin but clarithromycin has an additive effect active against

A

H. Influenzae

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10
Q

if a patient presents with chlamydia and gonorrhea what would you use to treat respectively

A

azithromycin for chlamydia and cephalosporin for gonorrhea

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11
Q

macrolides are special in that they can act on

A

intracellular pathogens

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12
Q

you want to treat syphillis but the person is allergic to penicillin

A

give them erythromycin

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13
Q

what intracellular pathogens can erythromycin be treated against

A
  1. Mycoplasma, Legionella, Chlamydia spp., and certain atypical mycobacteria.
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14
Q

what gram + can erythromycin be treated against

A

is effective against Gram positive organisms like Streptococci, Staphylococci, and Corynebacterium (i.e. diphtheriae).

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15
Q

what is the drug of choice for you to use to treat a chlamydial infection while the person is pregnant

A

erythromycin

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16
Q

what is the pharmacokinetics for macrolides and what is so special about erthromycin

A

macrolides are absorbed well orally and is distributed with high intracellular concentration. Erythromycin is given as esters or in enteric coated tablet to protect against stomac acid(unstable in acid). It will then be absorbed in the small intestine

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17
Q

explain the metabolism of the different types of macrolides

A

erythromycin is metabolized by Ctycrome p450 into an inactive metabolite

clarithromycin unlike erythromycin, clarithromycin does have an active metabolite which does actually play a role in its antibacterial activity

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18
Q

macrolides are excreted as

A

excreted both in the urine as well as the bile. These are pretty large molecules and so they are more likely to be excreted in the bile rather than in the urine

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19
Q

macrolides have no effect on

A

pregnant women

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20
Q

patient comes in with epigastric distress from taking an antibiotic…what do you think it is and why

A

erythromycin becuase of the stimulation of the gastric motilin receptor

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21
Q

clarithromycin and erythromycin exhibit similar effects…what are they

A
  1. epigastric distress
  2. Cholestatic jaundice (estolate)
  3. Ototoxicity(like vancomycin)

Drug interactions- inhibits the metabolism of many drugs including warfarin, cyclosporine, and theophylline; digoxin

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22
Q

erythromycin causes cholestatic jaundice when it is given as

A

as a salt estolate

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23
Q

ototoxicity occurs in clarithromycin and erythromycin only at

A

high doses

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24
Q

which macrolide does not inhibit cp450 metabolism of other drugs

A

azithromycin

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25
Q

what are the results of the drug interactions of clarithromycin and erythromycine

A
  1. Hemorrhaging(warfarin)
  2. Nephrotoxicity renal damage (Cyclosporine)
  3. erythromycin inhibits the metabolism of (theophylline), high levels of theophylline can lead to agitation and GI distress
26
Q

cross resistance of erythromycin is between which two other protein synthesis inhibitors

A

clindamycin and chloramphenicol

27
Q

what is the mechanism of clindamycin

A

also binds to the bacterial 50S ribosomal subunit which interferes with the peptidyl transferase reaction.

Clindamycin is also bacteriostatic just like the macrolides

28
Q

what are clindamycins four resistance mechanisms

A
  1. Decreased penetrability
  2. Decreased affinity to binding site of 50s subunit
  3. Enzymatic inactivation by an O-nucleotidyl transferase (staph aureus)
29
Q

used topically to treat rosacea (i.e. red veins and puffy nose) and acne and dental infections by anaerobic bacteria

A

clindamycin

30
Q

effective against streptococci, most anaerobes including Bacteroides, Prevotella, Porphyromonas and other oral anaerobes

A

clindamycin

31
Q

clindamycin is used to treat toxoplasmosis with a combination with

A

pyrimethamine an analog of trimethoprim

32
Q

what are the pharmacokinetics of clindamycin

A

it is distributed well into bone and body fluids; it has 90% bioavailability, crosses placenta; does NOT cross the CNS

33
Q

similar to macrolides clindamycin accumulates where

A

in the macrophages and leukocytes

34
Q

how is clindamycin metabolized and excreted

A

metabolize most of the clindamycin and some of the metabolites are active. The metabolic products of clindamycin are excreted primarily via the bile and only a very small amount is excreted in the urine. The metabolites that are conjugated by liver enzymes are the ones that tend to undergo enterohepatic circulation.

35
Q

what are some therapeutic uses with clindamycin

A

used to treat refractory bone infections because it can penetrate bone

treatment of anaerobic pelvic infections and abdominal penetrating wounds

36
Q

clindamycin can serve as a substitute for what for acute orofacial infections in situations where the organisms are pencillinase producing

A

amoxicillin or pen V

37
Q

you can use clindamycin as an alternate to

A

amoxicilin or pen V for acute orofacial infections

or

as an alternative to penicilin-sensitive pateints requiring prophylaxis to prevent endocarditis

38
Q

adverse effects of clindamycin are

A

NVD

hypersensitivity rashes and fever

risk of superinfection(pseudomembranous colitis)

neuromuscular blockad at high IV doses

39
Q

another name for clindamycin is

A

lincosamidine

40
Q

what are the streptogramins and what is their mechanism of action

A

Group B: Hexadepsipeptides and Quinupristin

Group A: Macrolactones and Dalfopristin

41
Q

the combination of quinupristin and dalfopristin is called

A

synercid

30 quinupristin and 70 dalfopristin

42
Q

WHat is the mechanism of action of Dalfopristin and Quinupristin

A

Dalfopristin binds to 50s ribosomal subunit inactivates both the donor and acceptor sites of peptidyltransferase, and induces a conformational change to increase the binding of the group B streptogramin

Quinupristin prevents the translocation step

43
Q

Together, Dalfopristin and Quinupristin are what but individually they are ____

A

individually they are bacteriostatic, together they are bactericidal

44
Q

what are the mechanisms of resistance of synercid 3 ways

A

Methylation of 23 S rna binding site prevents binding of Group B(Quinupristin)

Bacterial enzymatic inactivation; particulary dalfopristin

increased efflux

45
Q

methylation of 23s RNA binding site prevents binding of

A

quinupristin

46
Q

dalfopristin is prevented from working by

A

enzymatic inactivation

47
Q

what are the pharmacokinetics of synercid(Quinu and Dalfo)

A

must be given IV

penetrates macrophages and PMNs

both undergo extensive non-enzymatic conversion to non-active products

48
Q

what is the excretion and relative half lives of Quinu and Dalfo

A

excretion 80% bile, 20% urine

they both have short half-lives

Quinuprisitin 0.85 hr

Dalfo 0.7 hr

49
Q

what are the adverse effects of Dalfo and Quinu

A

injection related pain, inflammation, edema, injection rreactions

NVD, headache

Myalgia, arthralgia

50
Q

synercid(quinu and dalfo) is not compatible with

A

saline

51
Q

what are the drug interactions in taking synersid and something else

A

Even though quinupristin and dalfopristin are not substrates for the cytochrome p450 enzymes, they can inhibit CYP3A4. People who are immunocompromised because they are taking an immunosuppressant like cyclosporine are at risk for serious infections and so in these cases you might have to use more serious and potentially dangerous antibiotics like Synercid. Therefore if the patient is on cyclosporine and needs to take Synercid, cyclosporine levels should be monitored.

52
Q

what do you even use streptogramin(Quinu and Dalfo) for

A

treatment of vancomycin resistant enterococcus faecium

NOT faecalis

53
Q

what two drugs do we reserve for really serious infections

A

Oxazolidinone and Streptogramins

54
Q

What drugs go under oxazolidinone

A

Linezolid(synthetic) and thats IT

55
Q

what is the mechanism of linezolid

A

binds to 50 s subunit similar to chloramphenicol and prevents the formation of the 70S initiation complex

56
Q

Linezolid mechanism has some resistant strains with

A

staph aureus but no cross resistance with other antibiotics

57
Q

what organisms confers cross resistance

A

macrolides and clindamycin

58
Q

what is linezolid treated for

A

similar to vancomycin and gram positive anaerobes

approved for nosocomial pneumonia, community-acquired pneumonia, skin infections, vancomycin resistant enterococcal infections, MRSA

59
Q

what is the pharmacokinetics of linezolids

A

orally active: 100 % bioavailability

Distributed to well perfused tissues

Metabolized to 3 inactive metabolites non-enzymatically

30% renal and 65% biliary

60
Q

adverse effects for linezolid include

A

GI disturbances NVD, tongue discoloration

Hematologic: anemia thrombocytopenia, neutropenia requires weekly monitoring

headache

rashes

pseudomembranous colitis

exam 1 drugs dpphuckt (8 decks)

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