Tetracyclines

Question 1

What are tetracyclines?

Answer 1

broad-spectrum antibiotics that are used extensively throughout the world.

Question 2

What drugs are in the tetracycline group

Answer 2

tetracycline, demeclocycline, doxycycline (Doxy, Doxychel, Vibramycin), and minocycline (Minocin)

Question 3

which tetracycline is used primarily for syndrome of inappropriate antidiuretic hormone.

Answer 3

Demeclocycline

Question 4

MOA of tetracyclines

Answer 4

inhibit protein synthesis by reversibly binding to the 30S subunit of the bacterial ribosome and preventing the addition of amino acids to growing peptides.

Question 5

Activity of tetracyclines

Answer 5

good activity against gram-positive organisms, activity against some gram-negative bacteria

Question 6

mechanism of resistance to tetracyclines

Answer 6

The mechanisms of resistance to tetracyclines are (1) decreased intracellular accumulation due to impaired influx or increased efflux of an active transport protein pump, (2) ribosome protection by proteins that interfere with drug binding, and (3) enzymatic inactivation. Resistance to tetracycline generally predicts resistance to the entire class

Question 7

Absorption of tetracyclines

Answer 7

adequately. The percentage of oral dose absorbed is highest for doxycycline and minocycline (95% to 100%) and intermediate for tetracycline (60% to 70%)

Question 8

Distribution of tetracyclines

Answer 8

Doxycycline and minocycline are highly lipid soluble. found in tissues

Question 9

Which tetracycline needs to be renally dosed? Which does not?

Answer 9

Tetracycline needs renal dosing. doxycycline and minocycline do not significantly accumulate or require dosage reductions for renal impairment.

Question 10

Metabolism of tetracyclines

Answer 10

liver metabolism

Question 11

Excretion of tetracyclines

Answer 11

Tetracyclines are eliminated by the kidney via glomerular filtration and undergo enterohepatic recirculation with excretion in the bile and feces

Question 12

Can tetracyclines be used during pregnancy and breastfeeding?

Answer 12

Doxycycline and other tetracyclines should not be used in pregnancy.
Short term breastfeeding ok

Question 13

Can children use tetracyclines

Answer 13

Children younger than 8 years generally should not use tetracyclines. These drugs form a stable calcium complex in any bone-forming tissue, decreasing bone growth.

Question 14

Besides GI upset, what adverse reactions are related tot tetracycline use

Answer 14

GI Symptoms including C. Diff
Pseudotumor cerebri (benign intracranial hypertension) has also been associated with tetracyclines. Symptoms are headache and blurred vision
Photosensivity, SJS

Question 15

What drug interactions do tetracyclines have?

Answer 15

Mainly with elements.
with divalent and trivalent cations that are found in antacids, iron salts, sevelamer, magnesium-containing laxatives, and zinc supplements.

Question 16

Clinical use of tetracylines

Answer 16

STIs, Acne, H. Pylori

Question 17

Doxycycline is the primary drug choice for which conditions/infections

Answer 17

ehrlichiosis and rickettsial infections (e.g., Rocky Mountain spotted fever, typhus, Q fever, and trench fever caused by B. quintana)

Question 18

What drug level should be closely monitored when taking a tetracycline

Answer 18

digoxin