50s Protein Synthesis Inhibitors Med Chem

Question 1

Which of these antibiotics are Macrolide and Ketolide antibiotics?(select all)

A. Erythromycin

B. Clarithromycin

C. Clindamycin

D. Azithromycin

E. Telithromycin

Answer 1

A, B, D, E

Macrolide and Ketolide= thromycin

Erythromycin

Clarithromycin

Azithromycin

Telithromycin

Question 2

Which of these Antibiotics is a Lincosamide?

A. Clindamycin

B. Erythromycin

C. Azithromycin

D. Linezolid

E. Chloramphenicol

Answer 2

A

Lincosamide= Lin

Clindamycin

Question 3

Which of these medications is an Oxazolidinone antibiotic?

A. Clindamycin

B. Linezolid

C. Azithromycin

D. Quinupristin

E. Chloramphenicol

Answer 3

B

Oxazolidinone= zolid

Linezolid

Question 4

Which of these medications is a Streptogramin?

A. Quinupristin/ Dalfopristin

B. Erythromycin

C. Azithromycin

D. Chloramphenicol

E. Clindamycin

Answer 4

A

Just have to remember it

Question 5

All of the following antibiotics are 50s protein synthesis inhibitors EXCEPT:

A. Erythromycin

B. Gentamicin

C. Clindamycin

D. Linezolid

E. Quinupristin/dalfopristin

F. Chloramphenicol

Answer 5

B

Gentamicin is an aminoglycoside antibiotic that is used to inhibit 30s ribosomes.

Do you remember what bacteria it was synthesized from?

Streptomyces or Micromonospora?

Question 6

Answer the following question provided in the picture.

Answer 6

A. I

Question 7

Answer the following question in the picture provided.

Answer 7

C

Question 8

Macrolides contain an aminosugar group in thier structure. Which group is the aminosugar?

A. Red

B. Blue

C. Green

Answer 8

A

Question 9

Macrolides contain a Ketone in their structure. Which of these groups is the ketone?

A. Red

B. Blue

C. Green

Answer 9

B

Question 10

Macrolides contain a Lactone (Cyclic Ester) in their structure. Which of these circled groups is a Lactone?

A. Red

B. Blue

C. Green

Answer 10

C

Question 11

(Information slide): She wants us to be able to distinguish between a macrolide and an aminoglycoside based on structure. As you can see there are some major differences. Be sure to pick out the glycosidic bonds and the aminohexose sugar that are circled in the aminoglycoside and the lactone and aminosugar that is circled in the Macrolide.

Question 12

What is the mechanism of action of Macrolide antibiotics?

A. Binds to 23s rRNA of the 30s subunit and blocks the polypeptide exit tunnel and prevents the protein from leaving.

B. Binds to the 23s rRNA of the 50s subunit and blocks the polypeptide exit tunnel and prevents the protein from leaving.

C. Irreversibly binds to PBP and prevents the peptidoglycan cross-linking from occuring.

D. none of the above

Answer 12

B

Need to look at picture in order to get a good image of whats happening

Question 13

Which of the following statements is true regarding macrolide antibiotics? (Select All)

A. Have bacteriocidal activity

B. Have bacteriostatic activity

C. Can be used in PCN-allergic patients

D. Bind to the 23s rRNA of the 50s subunits of bacteria

E. Are broad spectrum antibiotics

Answer 13

B, C, D, E

Question 14

What is the bacterial resistance to macrolide antibiotics?

A. rRNA of the 50s ribosome will undergo methylation and prevent the macrolides from binding to rRNA (caused by erm gene in bacteria)

B. Drug efflux (due to mefA pump)

C. MLS phenotype

D All of the above

Answer 14

D

Erythromycin ribosomal methylase= erm gene

Question 15

The MLS Phenotype is a unique form of resistance to macrolide antibiotics. What classes of medications will bacteria be resistant to if the MLS phenotype is Constitutively expressed in a particular bacteria? (Select All)

A. Macrolide antibiotics

B. Oxazolidineone antibiotics

C. Lincosamide antibiotics

D. Chloramphenicol antibiotics

E. Streptogramin antibiotics

Answer 15

A, C, E

M- Macrolides

L- Lincosamides

S- Streptogramin

Question 16

Which of these medicaitons will a bacteria that is consitutively expressing the MLS-Phenotype be resistant to? (Select All)

A. Linezolid

B. Azithromycin

C. Clindamycin

D. Chloramphenicol

E. Quinupristin/Dalfopristin

Answer 16

B, C, E

Question 17

Which of these medications will a bacteria that has undergone Inducible expression of the MLS-Phenotype be resistant to? (Select All)

A. Azithromycin

B. Clindamycin

C. Linezolid

D. Quinupristin/Dalfopristin

E. Erythromycin

Answer 17

A, E

When bacteria are induced to express the MLS phenotype then they will only be resistant to Macrolide antibiotics

Question 18

Which of these statements regarding the uses of Macrolide antibiotics is true?

A. Used to treat Upper and Lower respiratory tract infections

B. Used to treat Gastric Ulcers (Clarithromycin)

C. Used to treat against gram negative bacteria only

D. A and B

Answer 18

D

Question 19

Which of these salts can be given with the macrolide Erythromycin in order to make it water soluble and given parenterally? (Select All)

A. Glucoheptonate

B. Estolate

C. Stearate

D. Ethylsuccinate

E. Lactobionate

Answer 19

A, E

How I remember:

Glucoheptonate has gluco in it meaning sugar and sugar is soluble in water (or tea :D)

Lactobionate has lacto in it like milk and milk can be watered down…which is gross. D:<

Question 20

Which of these salts can be given with the macrolide antibiotic Erythromycin to make it water-insoluble and able to be given Orally? (Select All)

A. Estolate

B. Stearate

C. Glucoheptonate

D. Lactobionate

E. Ethylsuccinate

Answer 20

A, B, E

I just remember the acronym “SEE! dat cray cray %&#@ is eating them antibiotics!”

S- Stearate

E- Estolate

E. Ethylsuccinate

Question 21

Erythromycin is considered Acid-unstable due to forming a ____ and causing _____.

A. Ketal, gut cramps

B. Ketone, gut cramps

C. Carboxylic, gut cramps

D. Carbonyl, gut cramps

Answer 21

A

The two ways they counteracted this is by putting it in an enteric coated tablet so it wouldn’t interact with stomach acid and the other way was structural modification. She does want you to know the ketal formation and gut cramps because it happened to her.

Question 22

How is the unpleasant taste from Erythromycin masked?

A. Made in a water-insoluble dosage form

B. Made in a hydrophilic dosage form

C. Given rectally

D. None of the above

Answer 22

A

If erythromycin is made in a water-insoluble dosge form then that means your saliva wont dissolve it when you are in the process of swallowing the medication, thus keeping the bad taste out of your mouth.

It also reduces acid instability and reduces chances of gut cramps.

Again this was just something she had in red on her slides

Question 23

Azithromycin was made by altering the structure of the group circled in Erythromycin. What was the purpose of adding this N-Methyl group between C-9 and C10 and removing the Carbonyl group?

A. Makes the drug more lipophilic

B. Removes the possiblity of forming a ketal group

C. To protect against gut-cramp side effects

D. B and C

Answer 23

D

without the carbonyl it cant form the ketal group and without that you will reduce the chances of gut cramps. Azithromycin also has a much longer half-life of 68 hr so the structure alteration was an improvement over erythromycin.

With the new N-Methyl group it also makes it an Azalide and gives it a post-antibiotic effect.

Question 24

Another structural modification was made to Erythromycin when Clarithromycin was produced. The group that swapped on the 6th carbon is known as a ____ group and was done to stop the formation of the ___ group.

A. Methoxy, Ketal

B. Ethanol, Ketal

C. Methoxy, Ketone

D. Ethanol, Ketone

Answer 24

A

Remember the reason they are doing these structural modifications in the newer drugs is to prevent that ketal formation in order to reduce gut cramps.

Question 25

What are some of the adverse effects of macrolide antibiotics? A. Gi discomfort B. Hepatotoxicity C. QT prolongation D. All of the above

Answer 25

D All of these can be caused by macrolide antibiotics especially with **Erythromycin** and **Clarithromycin** but they are less likely with **Azithrymycin**

Question 26

Macrolides are substrates and strong inhibitors for which of these enzymes? A. CYP2C9 B. CYP3A4 C. CYP2C19 D. CYP2E1

Answer 26

B. CYP3A4 **Erythromycin** and **Clarithromycin** are _major substrates and strong inhibitors_ for CYP3A4 but **Azithromycin** is a minor substrate for CYP3A4 in comparison. For these reasons and reasons stated before azithromycin is a **first choice macrolide**.

Question 27

What is the importance of this long chain that was added to Ketolide antibiotics that the macrolide antibiotics don't have? A. Increases activity against erythromycin-resistant micro-organisms. B. Increases binding affinity to the 23s rRNA of the 50s ribosome. C. Increases acid resistance D. A and C E. A and B

Answer 27

E

Question 28

What is the purpose of this methoxy group located on the C-6 carbon? A. Increases acid stability B. Increase binding affinity to the 23s rRNA on the 50s ribosome C. Makes the molecule look awesome D. none of the above

Answer 28

A Remember the clarithromycin also had a methoxy added to that same carbon and it was done to increase acid stability, otherwise it would form the ketal group in acidic conditions and cause gut cramps.

Question 29

What is the significance of the structural groups circled in Clindamycin? (select all) A. The large Octoside (8-carbon sugar) allows it to be more lipophilic B. The Chloro group gives it more hydrophilicity C. The Chloro gorup makes it more lipophilic D. Both groups give the molecule good oral bioavailability

Answer 29

A, C, D

Question 30

The OR in clindamycin makes it a prodrug. If the OR group is a phosphate ester it will be given ____ and if it is a Palmitate ester it wil be given \_\_\_\_ A. Parenterally, Orally B. Orally, Parenterally

Answer 30

A Not sure if she wanted us to know this but it wasn't in red. Palmate ester consits of 16 carbons so it makes it very lipophilic meaning it is good for oral administration. Phosphate esters have a charge on them so its better for parenteral administration

Question 31

All of the following statements are true regarding clindamycin EXCEPT: A. Primarily active against Gram positive bacteria and Anaerobic bacteria B. Has excellent activity against Propiobacterium Acnes (Acne treatment) C. Resistance is the same as macrolides (MLS-Phenotype) D. Black box warning includes Pseudomembranous colitis E. Binds to 30s subunits on bacteria

Answer 31

E Everything mentioned here was written in red

Question 32

The antibiotics **Quinupristin and Dalfopristin** are Streptogramin antibiotics and are given together. Which of the following statements is true regarding these medications? A. They are synergistic to each other. B. Dalfopristin binds to 23s rRNA on the 50s ribosome and increases the binding affinity for Quinupristin. C. Used to treat Vancomycin Resistant Enterococcus (VRE) D. Same bacterial resistance as the Macrolides (MLS-Phenotype) E. All of the above

Answer 32

E

Question 33

Answer the following question provided in the picture.

Answer 33

C

Question 34

What is the name of the structure circled in Linezolid? A. Lactam B. Lactone C. Oxazolidinone D. none of the above

Answer 34

C

Question 35

Linezolid is an antibiotic that is primarily acts on gram\_\_\_ bacteria A. Positive B. Negative

Answer 35

A

Question 36

Which of the following statements are true regarding Linezolid? A. Can cause Myelosuppression B. Need a CBC weekly when on this medication C. Can cause optic neuropathy (visual tests required) D. 100% bioavailable after oral absorption E. All of the above

Answer 36

E