Wk 12. AntiDiuretics Flashcards
- When should diuretics be taken?
In the morning if daily, morning and 2 pm if bid
- Where does the most reabsorption take place?
Proximal convoluted tubule
- Where is 20% of the sodium reabsorbed?
Ascending loop of Henle
- Which diuretics have the greatest potential for diuresis? Why?
Osmotic diuretics followed by loop diuretics.
They block sodium reabsorption at sites where more sodium is normally reabsorbed.
- Large dose of loop diuretics may adversely affect what organ?
Ear, ototoxicity
- What permanent adverse effect may occur with ethacrynic acid (Edecrin)?
Ototoxicity
- What change in calcium may occur with loop diuretics?
Hypocalcemia
- What class of diuretics does not cause calcium loss?
Thiazides
- What change in blood sugar may be seen with loop diuretics?
Hyperglycemia
- Thiazide diuretics are contraindicated with an allergy to what?
Sulfonamides
- When might thiazide diuretics be ineffective?
When the glomerular filtration rate (GFR) is below 15-20 mL/min
- What are some signs of electrolyte imbalance?
Muscle weakness, twitching, nausea and vomiting, dysrhythmias, dry mouth and thirst, confusion, etc.
- Loop diuretics decrease which electrolytes?
K+, Na+, Cl-, Ca2+, Mg2+
- The coadministration of digoxin (Lanoxin) and diuretics may precipitate what condition?
Digoxin toxicity with dysrhythmias.
- Potassium-sparing diuretics should not be used with which three antihypertensive drug categories? Name two common potassium-sparing diuretics.
ACE inhibitors, Angiotensin II receptor blockers, direct renin inhibitors.
Spironolactone (Aldactone) and triamterene (Dyrenium)
- Diuretics and antihypertensive drugs can cause what adverse effect?
Additive hypotension
- Why are osmotic diuretics used in renal failure?
To maintain urine flow through the tubule.
- Why are osmotic diuretics used for cerebral edema?
Used to reduce intracranial pressure
- What is added to deter patients from taking diphenoxylate (Lomotil) for analgesic effects?
Atropine, causes dry mouth and tachycardia.
- Name 2 contraindications for Diphenoxylate (Lomotil)?
Infectious diarrheas and pseudomembranous colitis.
- What are the mechanisms of action for bulk-laxatives? Where do they work?
Form nondigestible gel that expands with bacterial action. The enlarged fecal size triggers peristalsis. Small intestine and colon.
- List contraindications for laxatives. Why?
Abdominal pain, nausea, cramps, appendicitis, bowel obstruction, diverticulitis, ulcerative colitis, enteritis.
Worry about bowel perforation.
- Why must a bulk laxative be administered with a full glass of fluids?
To prevent bowel obstructions.
- What are the mechanisms of action for surfactant laxatives? Where do they work?
Decrease surface tension allowing water to penetrate stool, inhibit fluid absorption in gut, and increase water and electrolyte secretion into gut. Small intestine and colon.
- What is the difference between Docusate sodium (Colace) and Peri-Colace?
Peri-Colace includes a stimulant laxative, sennosides.
- What are the mechanisms of action for stimulant laxatives? Where do they work?
Increase peristalsis, inhibit fluid reabsorption in gut, and increase water and electrolyte secretion in gut. Colon.
- What food substance and drug category may not be taken with Bisacodyl (Dulcolax), a stimulant laxative? Why?
Milk and antacids. They dissolve the enteric coating meant to protect the stomach from the drug.
- What harmless urinary side effect is caused by senna, a stimulant laxative?
Yellowish-brown or pinkish urine.
- What are the mechanisms of action for saline laxatives? Where do they work?
Attracts water that stretches the gut and causes peristalsis. Small intestine and colon.
- What is a non-GI contraindication to magnesium hydroxide? Why?
Renal disease. Magnesium accumulates and causes CNC toxicity.
- What are the mechanisms of action for sugar laxatives? Where do they work?
The disaccharide is metabolized into acid by gut bacteria. The acids cause an osmotic action. Colon.
- Name a non-GI use for lactulose?
High ammonium blood levels.
- What are the mechanisms of action for glycerin suppositories? Where do they work?
Softens and lubricates stool. Stimulates rectal contraction. Rectum.
- What is the most important indication of constipation?
Hard, pellet-like feces.
- What is a possible effect of laxatives during pregnancy?
Initiation of labor.
- Discuss the use of laxatives during lactation.
The drug may be found in breast milk.
