Exam 2- Week 6

Question 1

Patients with noninfectious diarrhea while taking antibiotics

Answer 1

If severe diarrhea occurs, the patient should contact the prescriber before initiating any treatment. For mild diarrhea, they can use adsorbent antidiarrheal agents containing attapulgite (e.g., Donnagel) but should avoid antiperistaltic agents that promote the retention of toxins. Avoid dehydration

Question 2

Fluoroquinolines (-floxacin)

Answer 2

Targets DNA and replication by interfering with DNA gyrase. Very potent, broad spectrum drugs.

Ex: Cipro, levofloxacin, moxifloxacin

Side effects: Steven’s Johnson’s Syndrome, QT prolongation, C-diff infection, angina, ventricular ectopy.

Drug to drug interactions: drug to drug interaction with fluoroquinolones relates to the formation of insoluble chelate caused by antacids, bismuth subsalicylate, iron salts, sevelamer, sucralfate, and zinc salts thereby decreasing the absorption fluoroquinolones drugs.

Question 3

Treatment of Lyme disease

Answer 3

Doxycycline, 100 mg twice daily, is the first-line drug of choice for early treatment of Lyme disease, a tick-borne infection caused by B. burgdorferi. Children age 8 years or older are treated with doxycycline 4 mg/kg/d divided into twice daily doses (maximum 100 mg twice daily).

Question 4

Doxycycline

Answer 4

Tetracycline

Anorexia, nausea, vomiting, and diarrhea are caused by direct irritation of the intestinal mucosa. Taking the drug with food (note food interactions above) or reducing the dose usually alleviates GI complaints. Esophageal ulcers have occasionally occurred but can be avoided by taking the drug with a full glass of water and remaining upright after taking the drugSide effects:

Question 5

Vancomycin

Answer 5

Lipoglycopeptide

Because of poor oral absorption, oral forms of vancomycin should not be used to treat systemic infections. Oral formulations are unlikely to cause systemic adverse effects. However, clinically significant serum concentrations may occur in some patients who have inflammatory conditions of the intestinal mucosa. Oral vancomycin is listed as Pregnancy Category B, and IV forms are Pregnancy Category C.

Question 6

Azithromycin

Answer 6

Macrolides

Mechanism of action: inhibits protein synthesis

Question 7

Macrolides (-mycin)

Answer 7

Block protein synthesis.
Bind to bacterial ribosome and prevent protein production.

Bacterial resistance is a significant problem.

Ex: erythromycin, azithromycin, clarithromycin

Question 8

Tetracyclines

Answer 8

Block protein synthesis by entering cells by passive diffusion.

Broad spectrum, but has resistance issues.

Ex: tetracycline, doxycycline, minocycline.

Contraindications: those with renal impairment (usual doses of tetracyclines, except doxycycline and minocycline, may lead to excessive accumulation of the drugs and possible hepatotoxicity), those with hepatic impairment (serious concerns related to hepatotoxicity for IV forms of tetracycline), pregnant women (doxycycline is Pregnancy Category D. Others are Pregnancy Category X and should not be used during pregnancy. They readily cross the placenta in concentrations up to 60% of maternal plasma. Tetracyclines are found in fetal tissue and can produce retardation of skeletal development in the fetus and staining of deciduous teeth), lactating women (Tetracycline 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), and children under 8 years of age (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). In addition, outdated tetracyclines should not be administered.

Question 9

Rifampin

Answer 9

Inhibits proteins synthesis by inhibiting bacterial RNA polymerase.

Question 10

Aminoglycosides (-cin)

Answer 10

Bind to outer membrane of bacteria and form holes through which the drug passes, and then binds to bacterial ribosome and inhibits synthesis of new protein.

Reserves for serious infections.

Ex: streptomycin, neomycin, gentamicin, tobramycin, amikacin

Question 11

Sulfonomides

Answer 11

Target DNA and replication

Bacteriostatic. Prevents synthesis of bacterial folic acid.

Trimethoprim-sulfamethoxazole (TMP-SMX, Bactrim)

TMP not a sulfa but works on same pathway

Question 12

Lancosamides

Answer 12

Target protein synthesis. Very similar to Macrolides.

Wide range of uses, no gram-negative coverage.

Ex: clindamycin