tetracyclines

Question 1

What are members of the tetracycline family known for?

Answer 1

Broad-spectrum antibiotics

Nine tetracyclines have been introduced into medical use, including doxycycline and minocycline.

Question 2

When was the first tetracycline isolated, and what was it called?

Answer 2

1948, chlortetracycline (Aureomycin)

Isolated from Streptomyces aureofaciens.

Question 3

What is the significance of chlortetracycline compared to streptomycin and penicillin?

Answer 3

Wide range of activity and can be administered orally.

Question 4

What is the basic ring system of all tetracyclines?

Answer 4

Octahydronaphthacene

It consists of a 4-six-membered ring system.

Question 5

What affects the stereochemistry of tetracyclines?

Answer 5

Substituents on carbon atoms 4, 4a, 5, 5a, 6, and 12a.

Question 6

What is the general absolute configuration of tetracyclines?

Answer 6

4S, 4aS, 5aS, 6S, 12aS.

Question 7

Which tetracycline is considered the prototype?

Answer 7

Tetracycline

It was first obtained by catalytic hydrogen lysis of chlortetracycline.

Question 8

What is the pKa value of the OH at position 3 in tetracyclines?

Answer 8

3.3.

Question 9

What behavior do tetracyclines exhibit in neutral solutions?

Answer 9

Amphoteric behavior.

Question 10

What happens to tetracyclines in the presence of strong acids and bases?

Answer 10

They lose activity through modification of ring C.

Question 11

What is 6-demethyl chlortetracycline also known as?

Answer 11

Declomycin.

Question 12

What advantage does 6-demethyl chlortetracycline have over chlortetracycline?

Answer 12

More stable to dehydration in aqueous acidic solution.

Question 13

What is the most potent tetracycline currently employed in therapy?

Answer 13

Minocycline.

Question 14

What is Tigecycline developed in response to?

Answer 14

Growing rate of antibiotic-resistant bacteria.

Question 15

What is the trade name for Tigecycline?

Answer 15

Tygacil.

Question 16

What is Omadacycline classified as?

Answer 16

A broad-spectrum antibiotic belonging to the aminomethylcycline subclass.

Question 17

What is the primary route of excretion for doxycycline?

Answer 17

Bile and feces.

Question 18

What is the consequence of tetracyclines being chelating agents?

Answer 18

They form insoluble complexes with trivalent and divalent metals.

Question 19

What can cause staining of teeth when taking tetracyclines?

Answer 19

Chelation of calcium in growing bones and teeth.

Question 20

What is the effect of epimerization on tetracyclines?

Answer 20

Leads to the formation of less active isomers.

Question 21

What is the main reason tetracyclines should not be taken with milk products?

Answer 21

They chelate calcium, reducing absorption.

Question 22

What type of infections is Tigecycline used to treat?

Answer 22

Complicated skin and structure infections, complicated intra-abdominal infections, community-acquired bacterial pneumonia.

Question 23

What is a unique feature of doxycycline compared to other tetracyclines?

Answer 23

It does not accumulate in patients with impaired renal function.

Question 24

Fill in the blank: The general structure of tetracyclines can be represented as _______.

Answer 24

4S, 4aS, 5aS, 6S, 12aS.

Question 25

True or False: All tetracyclines can be administered orally.

Answer 25

True.

Question 26

What are tetracyclines known for?

Answer 26

Broad spectrum bacteriostatic agents, bacteriocidal in high doses ## Footnote Tetracyclines inhibit protein synthesis by blocking the binding of amino-acid-charged t-RNA.

Question 27

What should tetracyclines not be taken with?

Answer 27

Milk products, antacids, antianemic agents, or other agents containing tri and di valent metal salts ## Footnote These substances can impair the absorption of tetracyclines.

Question 28

What adverse effects can tetracyclines cause in children?

Answer 28

Staining of teeth, dental hypoplasia, and bone deformation ## Footnote Tetracyclines chelate calcium and are deposited in growing bones and teeth.

Question 29

What is the mode of action of tetracyclines?

Answer 29

Bind to 30S ribosomal subunit, blocking the binding of amino-acid-charged t-RNA ## Footnote This inhibits protein synthesis and affects codon-anticodon interaction.

Question 30

What is one mechanism of resistance to tetracyclines?

Answer 30

Tetracycline efflux ## Footnote This mechanism allows bacteria to pump out tetracycline, reducing its effectiveness.

Question 31

List primary clinical uses of tetracyclines.

Answer 31

* Gastrointestinal ulcers caused by H. pylori * M. pneumoniae (in adults) * Chlamydia * Rickettsia * Vibrio cholera * Treat hyponatremia ## Footnote These uses highlight the versatility of tetracyclines in treating various infections.

Question 32

List secondary clinical uses of tetracyclines.

Answer 32

* Alternative drug for syphilis * Respiratory infections caused by susceptible organisms * Prophylaxis against chronic bronchitis * Leptospirosis * Treatment of acne * Treat cancer patients with SIADH ## Footnote These uses indicate the broader applications of tetracyclines beyond primary infections.

Question 33

What are common adverse effects of tetracyclines?

Answer 33

* GI disturbances * Bony structures and teeth issues ## Footnote Adverse effects include fetal exposure, enamel dysplasia, and irregularities in bone growth.

Question 34

True or False: Tetracyclines can impair the absorption of oral contraceptives.

Answer 34

True ## Footnote Concurrent use of tetracyclines may render oral contraceptives less effective.

Question 35

Fill in the blank: Tetracyclines can cause fatal nephrotoxicity when used with _______.

Answer 35

Methoxyflurane ## Footnote The concurrent use of these drugs is contraindicated.

Question 36

What effect do antacids containing aluminum, calcium, or magnesium have on tetracyclines?

Answer 36

Impaired absorption of tetracyclines ## Footnote These antacids interfere with the effectiveness of tetracyclines.

Question 37

Name one tetracycline and its trade name.

Answer 37

Doxycycline, trade names include Vibramycin, Doryx, Monodox ## Footnote Doxycycline is available in oral and parenteral forms.

Question 38

What is the effect of bile acid sequestrants on tetracycline absorption?

Answer 38

May decrease tetracycline absorption ## Footnote This interaction can reduce the efficacy of tetracyclines.