Tetracyclines: Exam 1 Flashcards
Exam 1
What is the MOA of tetracyclines?
Inhibit protein synthesis by reversibly binding to the 30S subunit of the bacterial ribosome
Tetracyclines are mostly effective against gram:
Positive organisms
How well is doxycycline absorbed?
It’s absorbed about 95%-100% (the highest of the tetracyclines)
How well is tetracycline absorbed?
It’s absorbed about 60-70% (the highest of the tetracycline
General instructions for taking tetracyclines by mouth include:
Take on empty stomach
Tetracyclines interact with these foods/OTC drugs:
Antacids, dairy foods, iron salts, and sodium bicarbonate
If taking antacids or dairy products with tetracyclines an individual should do this:
Separate doses by 2 hours, and take tetracycline first
What are drugs which interact with tetracyclines?
Warfarin
Barbiturates
Carbamazepine
Hydantoins
Cimetidine
Digodix
Lithium
PO Contraceptives
Penicillin
Are doxycycline and tetracycline safe to give during pregnancy?
NO!
How is tetracycline typically prescribed?
Both topically and orally to treat acne and is one of four drugs in the combination treatment of H. pylori infection
Doxycycline is the most commonly prescribed tetracycline because it has the least:
amount of drug-food interactions
How is doxycycline distributed in the body?
-Highly lipid soluble
-Readily penetrates body tissues and fluids
-crosses placental membranes
-Fetal plasma concentrations reach 60% of maternal serum levels
Tetracyclines are eliminated & excreted via:
-The kidney via glomerular filtration
-Liver metabolism and undergo enterohepatic recirculation
Excretion: bile and feces
Tetracyclines require dose adjustments for:
Renal impairment
Tetracyclines are contraindicated in:
-Severe hepatic dysfunction
-pregnancy
-children younger than 8 years old
-severe renal impairment
Doxycycline is eliminated via:
30-42% unchanged in urine; remainder excreted in bile & feces
Tetracycline is eliminated via:
20%–55% unchanged in urine
What does current evidence say about lactation when using tetracycline?
Tetracycline: is excreted in breast milk; however, the it is compatible with breastfeeding because the serum concentrations were below detectable levels and there was no evidence of teeth staining
What does current evidence say about lactation when using doxycycline?
Doxy is excreted in breast milk; however, because milk levels are low and absorption is inhibited by the calcium in breast milk, a short course is considered safe during lactation
Why shouldn’t tetracyclines be given to children?
These drugs form a stable calcium complex in any bone-forming tissue, decreasing bone growth. They also may cause permanent yellow/gray/brown discoloration of deciduous and permanent teeth
Doxycycline is the primary drug of choice for:
Ehrlichiosis and rickettsial infections (e.g., Rocky Mountain spotted fever, typhus, Q fever, and trench fever caused by B. quintana)
What are some ADR when taking tetracyclines?
GI Upset (anorexia, N/V/D)
Esophageal ulcers
C. Diff
Pseudotumor cerebri (benign intracranial hypertension)
Hepatotoxicity
Superinfection
What are dermatological reactions associated with taking tetracyclines?
- Photosensitivity: manifested by an exaggerated sunburn, and a maculopapular/ erythematous rash.
- Severe skin reactions: Stevens–Johnson syndrome, toxic epidermal necrolysis
What are the primary drug-drug interactions associated with tetracyclines?
Divalent and trivalent cations found in antacids, iron salts, sevelamer, magnesium-containing laxatives, and zinc supplements
If the patient needs to eat while taking tetracyclines, give these instructions:
Administer tetracyclines 1 hour before or 2 hours after meals
To prevent esophageal irritation, give these instructions:
Do not take tetracyclines at bedtime and administer with a full 8 oz glass of water
Instructions on how to avoid phytotoxicity reactions when taking tetracyclines:
Wear sunscreen, hats, and protective clothing if it is necessary to be in the sun for more than a few minutes
What are signs of hepatotoxicity from taking tetracyclines?
Upper abdominal pain, nausea, vomiting, dark urine, clay-colored stools, or yellowing of skin or eyes
What are signs of a superinfection that should be reported?
Hoarseness, glossitis, sore throat, dysphagia, or vaginal itching and discharge
