N323 - Week 7 (GI Pharmacology NVCD)

Constipation

difficult or infrequent defecation

-results in less # of bowel movements per week, hard stools, straining

-primary & secondary constipation

Constipation is Caused by:

lack of exercise

-insufficient dietary fiber

-diminished fluid intake

-slow motility of waste material through large intestine

-certain foods, medications, disease

Primary Constipation

idiopathic, constipation is the main disease process

-due to lack of exercise, lack of fiber, lack of fluid intake, low GI motility

Secondary constipation

caused by another disease process or medication (e.g. opioid constipation)

Laxatives (4) & Antidiarrheal

Psyllium mucilloid (Metamucil).. bulk-type laxative

-Magnesium Citrate (Citroma)... saline laxative

-Docusate sodium (Colace).. surfactant laxative

-Bisacodyl (Dulcolax).. stimulant laxative

-Antidiarrheal: diphenoxylate w/ atropine (Lomotil)

Psyllium mucilloid (Metamucil)

MOA:

Classification:

Primary use:

Adverse effects:

Nursing Considerations: (4)

MOA: swells & increases size of fecal mass

Classification: bulk-type laxative

Primary use: to promote passage of stool

Adverse effects: rare; less cramping than stimulant-type laxatives

Nursing Considerations:

-assess bowel sounds, inquire on bowel patterns

-encourage pt to mix w/ sufficient water, fruit juice & drink immed.

-Ensure pt ability to swallow at least 8 oz w/o aspiration risk

-Many drugs will have a decreased absorption, please check pt med list

Magnesium Citrate (Citroma)

MOA:

Classification:

Primary use:

Adverse effects: (3)

Nursing Considerations: (3)

MOA: promotes bowel evacuation by causing osmotic retention of fluid which distends the colon w/ increased peristaltic activity

Classification: saline laxative

Primary use: bowel prep, constipation

Adverse effects: abdominal pain, diarrhea, flatulence

Nursing Considerations:

-monitoring electrolytes, stool output

-assessing bowel tones frequently

-contraindicated in bowel obstruction

Docusate sodium (Colace)

MOA:

Classification:

Primary use:

Adverse effects:

Nursing Considerations: (2)

MOA: reduces surface tension of the oil-water interface of the stool resulting in enhanced incorporation of water & fat allowing for stool softening

Classification: surfactant laxative

Primary use: constipation, post operative-short term

Adverse effects: abdominal pain, diarrhea

Nursing Considerations:

-close monitoring of stool output

-assess bowel sounds frequently

Bisacodyl (Dulcolax), senna (OTC)

MOA:

Classification:

Primary use:

Adverse effects:

Nursing Considerations:

MOA: irritates the smooth muscle of the intestine (stimulates peristalsis); alters water & electrolyte secretion producing net intestinal fluid accumulation & laxation

Classification: stimulant laxatives

Primary use: constipation

Adverse effects: abdominal cramping, electrolyte disturbances

Nursing Considerations:

-monitor Na, K

-monitor for diarrhea

-caution w/ geriatrics

Diphenoxylate w/ atropine (Lomotil)

MOA:

Classification:

Primary use:

Adverse effects:

Nursing Considerations: (4)

MOA: inhibits excessive GI motility & GI propulsion; commercial preparations contain atropine to discourage abuse

Classification: Opioid (Antidiarrheal)

Primary use: for moderate to severe diarrhea

Adverse effects: mild dizziness & drowsiness

Nursing Considerations:

-assess electrolytes

-assess for blood presence in stool

-assess for ambulation (walking) concerns

-Schedule V drug classification

Vomiting (Emesis)

defense mechanism used by body to rid itself of toxic substances

-controlled by the "vomiting center" in medulla of brain

Conditions associated w/ vomiting: (3)

infection, poisoning

-psychological factors, pain

-changes in body position

emetogenic potential

capacity of drug to induce vomiting

Antiemetics

treatment of nausea & vomiting

-mild to moderate nausea treated w/ OTC drugs & herbal options

-moderate to severe nausea treated w/ prescription drugs

Examples of Antiemetics (8)

1. prochlorperazine (dopamine antagonists)

2. ondansetron (HT3 receptor antagonists)

3. metoclopramide (dopamine antagonist, 5HT4 agonist)

4. dronabinol (cannabinoid)

5. dexamethasone (glucocorticoid)

6. promethazine (antihistamine..)

7. dimenhydrinate (antihistamine)

8. Scopolamine (anticholinergic

Prochlorperazine

MOA:

Classification:

Primary use:

Adverse effects: (6)

Nursing Considerations: (4)

MOA: blocks dopamine 1 & 2 receptors in brain to inhibit signal to vomiting center in medulla, anticholinergic

Classification: Phenothiazine (1st gen), Dopamine Antagonists (antiemetic)

Primary use: for severe nausea & vomiting

Adverse effects: dry mouth, sedation, constipation, orthostatic hypotension, tachycardia, extrapyramidal symptoms

Nursing Considerations:

-monitor for drowsiness, assess for fall risk

-Beers criteria - not for use in elderly pts (Box warning)

-Not for use in individuals w/ delirium or dementia

-anticholinergic effects

Ondansetron (Zofran)

MOA:

Classification:

Primary use:

Adverse effects:

Nursing Considerations: (3)

MOA: blocks serotonin, both peripherally on vagal nerve terminals and centrally in the chemoreceptor trigger zone

Classification: Selective serotonin 5-HT3 receptor antagonist (antiemetic)

Primary use: nausea, vomiting, chemotherapy prep

Adverse effects: H/A, malaise (fatigue), constipation, QT prolongation

Nursing Considerations:

-monitor for QT prolongation

-decrease dose in hepatic impairment

-used in pregnancy

metoclopramide (Reglan) PO, IV, IM

MOA:

Classification:

Primary use:

Adverse effects:

Nursing Considerations: (4)

MOA: blocks dopamine receptors, blocks serotonin receptors

Classification: Dopamine Antagonist, serotonin 5-HT4 receptor agonist, 5-HT3 antagonist (antiemetic)

Primary use: heartburn, GERD, slow peristalsis; vomiting prevention, CINV (Chemotherapy induced nausea & vomiting)

Adverse effects: tardive dyskinesia; CNS depression

Nursing Considerations:

-caution w/ use in elderly persons

-monitor for tardive dyskinesia

-administer PO doses 30 min prior to meals

-Many CYP interactions

dronabinol (Marinol)

MOA:

Classification:

Primary use:

Adverse effects:

Nursing Considerations: (3)

MOA: activates of the CB1 receptor in the central & peripheral nervous systems; increases appetite

Classification: cannabinoids (antiemetic)

Primary use: nausea, vomiting, pain mgmt.

Adverse effects: dizziness, lethargy

Nursing Considerations:

-close monitoring of CNS fxn

-monitor for fall potential

-caution w/ use in geriatric pts

Dexamethasone (Decadron); prednisone

MOA:

Classification:

Primary use:

Adverse effects:

Nursing Considerations:

MOA: reduce serotonin concentrations in the gut

Classification: glucocorticoid (corticosteroid) (antiemetic)

Primary use: many diagnoses; chemo induced nausea & vomiting (CINV)

Adverse effects: increased blood sugar, adrenal suppression, abdominal distension, emotional liability; insomnia

Nursing Considerations:

-monitor lab values, esp. glucose, electrolytes & LFTs

-cardiac monitoring in CV diagnoses

-monitor wound healing on this regimen

-readily cross placenta (strong caution in pregnancy)

Promethazine (Phenergan) Deep IM, Slow IV, PR, PO

MOA:

Classification:

Primary use:

Adverse effects:

Nursing Considerations:

MOA: blocks H1 receptors & muscarinic receptors as well as dopamine 2 receptors

Classification: Antihistamine; Phenothiazine derivative

Primary use:

Adverse effects: sedation, dry mouth, blurred eyesight, extrapyramidal symptoms

Nursing Considerations:

-box warning for respiratory depression in pediatrics

-Deep IM preferred; diluted if IV is route through large vein or central venous line

-monitor for anticholinergic effects

-short term use only

dimenhydrinate (Dramamine); meclizine (Anti-Vert) OTC

MOA:

Classification:

Primary use:

Adverse effects:

Nursing Considerations:

MOA: block histamine 1 & muscarinic cholinergic receptors in the neuronal pathway that connects inner ear to vomiting center

Classification: antihistamine (H-1)

Primary use: motion sickness; radiation sickness

Adverse effects: dry mouth, blurred vision, drowsiness

Nursing Considerations:

-On Beer list criteria

-monitor for sedation, especially w/ other medications

Scopolamine (Transdermal-Scop)

MOA:

Classification:

Primary use:

Adverse effects:

Nursing Considerations: (3)

**TOPICAL

MOA: blocks the axn of acetylcholine at parasympathetic sites in smooth muscle, secretory glands & the CNS

Classification: anticholinergic

Primary use: motion sickness, hospice

Adverse effects: dry mouth, blurred vision, drowsiness

Nursing Considerations:

-Patch is for 72 hrs

-Not for use in glaucoma (can increase intraocular pressure)

-Extrema caution w/ obstructive disease processes