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Pharmacology -- Test #2 > Clindamycin and Tetracycline Antibiotics > Flashcards

Clindamycin and Tetracycline Antibiotics Flashcards

(59 cards)

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1
Q

Clindamycin is synthesized from…

A

naturally occuring Lincomycin by treatment with Chlorine and Triphenylphosphine

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2
Q

Why isn’t Lincomycin used anymore?

A

Toxicity

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3
Q

Clindamycin mechanism of action

A

Inhibition of protein synthesis by binding the 23S RNA part of the 50S ribosomal subunit.

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4
Q

Reason to expect antagonism/cross-resistance between clindamycin and erythromycin?

A

It has the same binding site on the ribosome

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5
Q

Clindamycin is most effective against

A

Aerobic G+ Cocci

Anerobic G- bacilli

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6
Q

Most common uses for Clindamycin

A 
S. aureus bone infection
Topically for severe acne
Cream for bacterial vaginosis. 
Lung abscess
MRSA
Toxoplasma gondii in AIDS patients
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7
Q

When Clindamycin is used to treat AIDS patients, what other drugs are added

A

Pyrimethamine and Leucovorin

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8
Q

What is an important limiter of Clindamycin use?

A

It increases the incidence of C Diff pseudomembranous colitis

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9
Q

Dosage form of Clindamycin

A

Oral administration
IV (Clindamycin phosphate)
Topical foams/solutions)

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10
Q

Clindamycin is metabolized extensively by…

A

Cytochrome P450 enzymes in liver

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11
Q

Breakdown products of Clindamycin?

A

Sulfoxide

N-Demethylated Derivative

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12
Q

Approx __% of Clindamycin is absorbed in the GI

What about Clindamycin’s PK makes it especially useful

A

90

Can get through the BBB

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13
Q

Adverse effects of Clindamycin

A

Diarrhea, pseudomembranous colitis, nausea, vomiting, cramps, rash
Possibly contact dermatitis

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14
Q

Effects of pseudomembranous Colitis?

Treatment?

A

Diarrhea, Colitis, Toxic Megacolon

Metronidazole or Vancomycin

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15
Q

Tetracycline is produced by

A

Streptomyces

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16
Q

What happens when tetracyclines are exposed to polyvalent ions? Examples of polyvalent ions?

A

Tetracyclines for stable chelates

Ca++, Al+++, Cu++, Mg++

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17
Q

Consequences of Tetracycline forming insoluble chelates?

A

Can’t be administered with high calcium foods, antacids with multivalent metals, hemainics containing irons.

Can’t give to kids or it will mess up their teeth

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18
Q

Preferred route of administration for Tetracycline

A

Oral

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19
Q

Why can’t little kids use Tetracycline?

A

Tetracyclines chelate Ca during formation of teeth, causing them to be permanently brown or gray.
Discoloration gets worse over time from photooxidation

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20
Q

Why does it hurt to inject Tetracyclines?

A

Formation of insoluble Calcium complexes

Minimize with EDTA to chelatate Ca and buffered to acidic pH

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21
Q

What happens as a result of the hydrogen on the amine-bearing Carbon of Tetracycline?

A

Enolization

Epimerization

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22
Q

In the epimerization reaction, Hydrogen coming in from above will generate _____ and below will generate ______

A

Tetracycline

Epitetracycline (Inactive)

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23
Q

Why should we care about the Tetracycline epimerization reaction?

A

This is how old Tetracycline products can lose approximately half of their potency.

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24
Q

When is epimerization of Tetracycline slow? fast?

Study These Flashcards
A

Slow – Solid State

Fast – pH 4.0

25
What side group is especially set up to cause the dehydration reaction to occur?
The tertiary benzylic hydroxyl group at C6
26
End result of Tetracycline dehydration reactions
Anhydrotetracycline -- Inactive or 4-Epianhydrotetracycline -- Inactive and Toxic
27
Whats so bad about 4-Epianhydrotetracycline?
Toxic to Kidneys | Produces Fanconi-like syndrome (Failure of reabsorption in PCT)
28
Perk of Tetracycline derivatives without a C6 group?
No risk of dehydration toxicity
29
What happens to Tetracycline in pH 8.5 or above?
Generates a lactone product that is inactive.
30
Tetracycline mechanism of action
Bind the 30S ribosomal subunit and inhibit bacterial protein synthesis. Block attachment to the A site.
31
Do Tetracycline and Erythromycin interact competitively?
No, their binding sites do not overlap with eachother
32
Why doesn't Tetracycline trash the ribosomes of the host?
It can in super high doses, but usually won't be dosed high enough to. Bacteris have an uptake mechanism that makes Tetracycline especially effective against them.
33
Name the ribosomal site Tetracycline primarily binds to
Tet1
34
Therapeutic use of Tetracyclines?
Broad Spectrum Antibiotics Acne Chlamydia, Rickettsia, Brucellosis, Spirochetal Anthrax, Plague, Tularemia, Legionaire's
35
Tetracycline is made by _______ Perks? Cons?
Streptomyces aureofaciens Generic, inexpensive Food and Milk drop absorption by 50%
36
What is Dimeclocycline?
Tetracycline, but with a secondary hydroxyl at C6 instead of a tertiary hydroxyl.
37
Benefit of Dimeclocycline's change to a secondary hydroxyl?
It dehydrates more slowly because the secondary cation intermediate formed is less stable than the tertiary cation intermediate
38
Con of Dimeclocycline?
Food and Milk lower absorption by about 50%
39
What is Minocycline?
Dimeclocycline modified to lost the c6 hydroxyl group
40
perks of Minocycline?
No C6-hydroxyl means no acid-catalyzed dehydration No potential for 4epi.... toxicity 90-100% bioavailability
41
Cons of Minocycline?
``` Absorption down 20% when taken with food or milk Vestibular toxicities (vertigo, ataxia, nausea) ```
42
Oxytetracycline is made by
fermentation of Strep. rimosis
43
Important details for Oxytetracycline?
It fuckin sucks. pretty much replaced now. Most hydrophillic tetracycline.
44
Important structural details of Doxycycline?
It lacks a C-6 hydroxyl -- no dehydration = no toxicity
45
Bioavailability of Doxycycline? | With food/milk?
90-100% | Absorption lowered by approx. 20% when taken with food/milk
46
Half life of Doxycycline?
18-22 hours
47
First antibiotic to be manufactured synthetically on a large scale?
Chloramphenicol
48
Why don't people use Chloramphenicol so much anymore?
Toxicities | Still prevalent in the 3rd world because cheap
49
How does Chloramphenicol work?
It binds reversibly to the 50S ribosomal subunit near the erythromycin and clindamycin spot (competitive interactions occur). Specifically, it blocks peptide bond formation btw the P and A sites
50
Therapeutic use of Chloramphenicol?
Ointment/Eye drops | IV in severe disease states
51
Indications for IV Chloramphenicol
Bacterial Meningitis Typhoid Fever Rickettsial infections Intraoccular infections
52
How does resistance to Chloramphenicol happen?
Reduced membrane permeability 50S Ribosome Mutation Elaboration of Chloramphenicol acetyltransferase
53
What does Chloramphenicol acetyltransferase do?
Acetylates one/both ydroxyl groups to form metabolites that can't bind 50S
54
Toxicity risks for Chloramphenicol?
Aplastic Anemia Bone Marrow Suppression Childhood Leukemia Nausea, Vomiting, Diarrhea
55
Why does it take months after Chloramphenicol treatment to see Aplastic Anemia symptoms?
RBC life is 3-4 months | Takes time for the loss of new blood cells to be apparent
56
Highest risk way to use Chloramphenicol? Lowest?
Highest -- Oral | Lowest -- eye drops
57
How is Chloramphenicol metabolized?
Metabolized to glucuronide in the liver | Pharmacologically inactive and readily excreted
58
Mechanism for Chloramphenicol metabolism?
Nucleophilic attack of the less hindered primary alcohol of UDPGA, performed by glucuronyl transferase.
59
Can babies have Chloramphenicol?
No. Neonates can't metabolize it.

Pharmacology -- Test #2 (13 decks)

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