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Pharm Exam 2 > Antibiotics 2 - Vancomycin and Macrolides > Flashcards

Antibiotics 2 - Vancomycin and Macrolides Flashcards

1
Q

Vancomycin is what type of compound

A

Glycopeptide

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2
Q

Vancomycin is an inhibitor of…

A

Gram+ cell wall biosynthesis

*BInding of the peptidyl side chain D-ala-D-ala in the peptidoglycan precursor

**Inhibits the transpeptidation required for PG crosslinking

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3
Q

Vancomycin effects and spectrum

A

Bactericidal, effective against Gram + bacteria

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4
Q

What is the threshold for a “susceptible strain” in Vancomycin treatment?

Staph strains that are methicillin resistant are usually inhibited with…

A

MIC of 4 μ/mL

…with MIC of 1-5 μ/mL

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5
Q

VRE is connected to the use of ____

A

Avoparcin

(a glycopeptide AB)

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6
Q

Mechanism of resistance (VRE)

A

Mutation in precursor to PG cell wall

D-ala-D-ala –> D-ala-D-lactate

(1000x less affinity for the lactate one)

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7
Q

Vancomycin potential sides (3)

A

Hypersensitivity response

Nephrotoxicity (.1-1%)

Ototoxicity (rare)

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8
Q

Macrolide AB’s are ________

and _______

A

Macrocyclic lactones

Polyketides (sequential addn of proprionate groups to a growing chain)

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9
Q

Macrolide site of protonation

A

The N on the desosamine sugar

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10
Q

Production of Erythromycin

A

Propriony-CoA

(saccharopolyspora erythrea)

Erythronolide

(Converge with deoxyheose)

Erythromycin

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11
Q

pHa of the amine in erythromycin

A

8.8

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12
Q

The amine in erythromycin can form salts that are more soluble, including ___ and ____

A

Glucoheptonic acid

Lactobiononic acid

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13
Q

During peptide bond formation (transpeptidation), the polypeptide attached to the tRNA in the ____ is transferred to _____

A

polypeptide in the P site is transferred to the amino group of the aminoacyl-tRNA in the A site

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14
Q

Macrolides inhibit protein synthesis by binding _______

A

irreversibly to the P site – inhibiting the translocation from A to P

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15
Q

Macrolide binding involves the bacterial _____ and not _____

A

the bacterial 23S RNA and not the protein

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16
Q

Macrolide may be _____ or _____ depending on _______

A

bacteriostatic

bactericidal

concentration

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17
Q

Macrolides accumulate within ______

A

leukocytes

*transported to site of infection

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18
Q

Four mechanisms of macrolide resistance:

A
  1. Induction of lactone ester hydrolase (degrades by hydrolysis)
  2. Drug induced production of RNA methylase (methylated A2058 prevents eryth from binding to 50S)
  3. Adenine-> Guanine at A2058 (same as above)
  4. Efflux pump (active transport)
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19
Q

Resistance management for macrolides is especially important in regards to…

A

respiratory infections

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20
Q

Intrinsic macrolide resistance organisms

A

Pseudomonas

Enterobacter

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21
Q

Acidic inactivation of the parent molecule (macrolide) is a formation of _________________

A

intramolecular acid-catalyzed ketal formation

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22
Q

Oral erythromycin is administered as ____ or ______

A

enteric coated tablets or more stable salts or esters

23
Q

(Macrolide) Acid stability can be achieved with the ______

A

6-OCH3 derivative

=blocks ketal formation at low pH

–> enhances oral absorption

**this is CLARITHROMYCIN

24
Q

Amine analog that is acid stable

A

Azithromycin

25
Azithromycin structural difference
**N-methylated methylene-amino** moiety replaces the C9 ketone
26
Main route of erythromycin metabolism
demethylation in the liver ---\> main elimination route is in the bile
27
Erythromycin half life
1.5 hours
28
DDI for Erythromycin and clarithromycin Lower DDI drug?
They bind and **inhibit** **3A4** **Dirithromycin** has reduced capacity to inhibit p450's
29
Drugs that interact with macrolides
* Carbamazepine * Cyclosporin * Disopyramide * Midazolam * Quinidine * Rifampacin * Rifabutin * Theophylline * Triazolam * Zidovudine
30
\_\_\_ and ____ reduce the activity of erythromycin
rifampacin rifabutin
31
Other drugs that can have DDIs with macrolides
ergotamine digoxin methylprednisone
32
14-membered macrolides stimulate \_\_\_\_\_\_
GI motor activity
33
Serious allergic/immune responses from macrolides include ___ and \_\_\_\_
Steven-Johnson syndrome Toxic epidermal necrolysis
34
Long term macrolide use can induce...
reversible cholestateic hepatitis
35
Erythromycin can increase the probability of ____ in kids whose mothers took the med during pregnancy or breastfeeding
pyloric stenosis
36
Erythromycin is inactivated by gastric acids, so all formulations are...
given as **enteric coated capsules**
37
Erythromycin is rapidly absorbed and accumulates in high concentrations within...
phagocytes
38
During active \_\_\_\_, large amounts of Erythromycin are released
phagocytosis
39
the propionyl ester, lauryl sulfate prodrug of erythromycin
Erythromycin estolate
40
2 functions of the propionyl ester group in erythromycin estolate
* makes the drug more lipophilic than erythromycin itself * increases oral absorption and blood levels of erythromycin after oral administration
41
Pathophys of the erythromycin induced Cholestatic jaundice
1. The **bile becomes granular** in the bile duct 2. Granules **impedes** bile flow 3. Bile salts back up into the **circulation**
42
What must you do if a patient develops cholestatic jaundice while being given erythromycin
drug must be replaced by a nonmacrolide antibiotic
43
Erythromycin estolate is contraindicated in
patients with preexisting liver disease or dysfunction
44
Erythromycin Estolate is used to treat... (4)
* Beta hemolyric strep * Primary siphilis * amebic dysentery * Viridans endocarditis prophylaxis
45
Erythromycin Ethyl Succinate * It is a \_\_\_\_\_\_ * It is more ______ than erythromycin * It is used as a \_\_\_\_\_\_\_\_
* It's an ethyl succinate ester prodrug * It is more lipophilic and orally available * it is used as flavored oral suspension for kids
46
Clarithromycin is the ________ of erythromycin What does this do?
the **C-6 methyl ether** of erythromycin It **blocks ketal formation** and makes it more stabile in acid
47
Clarithromycin results in ________ due to reduction of ketals
reduced gastric upset *(gastric upset is usually caused by ketal degradation products)*
48
Clarith forms a _____ compound Which is especially good against \_\_\_\_\_
**14-(R)-Hydroxy** metabolite H. influenzae
49
Structure of azith: its a ____ ring (why?)
_15 membered lactone ring_ because an **N-CH3 group** has been inserted between C9 and C10, and the **carbonyl Oxygen** has been removed
50
Azith half life compared to eryth
Longer - terminal half life 68 hours
51
Magnesium / aluminum and Azithromycin?
Forms coordination complexes - prevents absorption
52
Major route of elimiation of azithromycin
53
Azithromycin has a greater activity against ____ than erythromycin or clarithromycin
Gram negatives
54
Most common side effects of azith
Diarrhea, nausea, abd. pain

Pharm Exam 2 (12 decks)

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