Antiemetics, Antispasmodics & Laxatives Flashcards Preview

Gastroenterology > Antiemetics, Antispasmodics & Laxatives > Flashcards

Flashcards in Antiemetics, Antispasmodics & Laxatives Deck (54):


1. Anticholinergics
2. Antihistamines
3. Dopamine receptor antagonists
4. Serotonin antagonists


WHat are the Dopamine receptor antagonists? 2

1. Phenothiazines
2. Benzamides


Neurotransmitter receptor sites involved in the vomiting reflex?

1. M1 – muscarinic
2. D2 – dopamine
3. H1 – histamine
4. 5-hydroxytryptamine (HT)-3
5. Neurokinin 1 (NK1) receptor
--substance P


Anticholinergic agents
1. Acts on what receptors?
2. Main drug in this category?
3. Predominantly used for what?
4. Administered how?
5. SE? 3

1. M1 – muscarinic receptor
2. Scopolamine is the main drug in this category
3. Predominantly used as prophylaxis against motion sickness
4. Delivered transdermally, 1.5 mg every 72 hours
5. Side effects include
-dry mouth,
-vision disturbance


1. MOA?
2. Primary use is for?
3. What are the drugs?
4. Common side effect?

1. H1 blockers
2. Primary use is for motion sickness

-Diphenhydramine (Benadryl)
-Cylizine (Cyclivert)
-Dimenhydrinate (Dramamine)
-Meclizine (Dramamine-Less Drowsy)

4. Sedation is a common side effect along with anticholinergic effects


Dopamine Receptor Antagonists
1. What are the phenothiazines?2
2. What are the benzamides? 2

1. Phenothiazines
-Prochlorperazine (Compazine)
-Promethazine (Phenergan)

2. Benzamides
-Metachlopramide (Reglan)
-Trimethobenzamide (Tigan)


1. Work on what receptor sites? 3
2. Commonly used as what line of agent?
3. Administration? 3

1. Have antagonistic properties at D2, H1 and M1 sites
2. Commonly used as first line agents
3. Oral, rectal or IV


Main adverse effects of the phenothiazines

1. Extrapyramidal reactions such as dystonia
--Compazine has higher incidence of EPS than Phenergan
2. Tardive dyskinesia with prolonged use
3. Acute dystonia can be treated with diphenhydramine 25 to 50 mg IV or IM

4. Hypotension can also occur, particularly in the elderly or with intravenous infusion

5. Sedation, drowsiness, anticholinergic effects (dry mouth, urinary retention, blurred vision)


Precautions with phenothiazines?

Use with caution in
1. elderly,
2. with other CNS depressants,
3. poorly controlled seizures,
4. severe liver dysfunction


Metachlopramide (Reglan)
1. MOA at low doses?
2. MOA at high doses?
3. How does it act on gastric smooth muscle? Neuromuscular junction?

Metachlopramide (Reglan)
1. Central and peripheral dopamine D2 antagonism at low doses
2. Weak 5-HT3 blockade at the higher doses

3. Stimulates cholinergic receptors on gastric smooth muscle cells and enhances acetylcholine release at the neuromuscular junction


Trimethobenzamide (Tigan)
1. Mechanism of action is unclear but works centrally in the area of the what?

2. Is generally considered the most potent antiemetic that does not have effects on the serotonergic, dopaminergic, or histaminergic systems, so it has a lower likelihood of causing what?

1. medulla oblongata

2. undesired side effects


Serotonin 5-HT3 Antagonists
1. Potent antiemetic properties mediated mainly through what?

central 5-HT3-receptor blockade in vomiting center AND chemoreceptor trigger zone blockade of 5-HT3 receptors


Serotonin 5-HT3 Antagonists Clinical Uses

1. Great for postoperative and chemotherapy induced nausea and vomiting

2. Can be used for most cases of nausea and vomiting except not great for nausea secondary to vestibular system etiology (vertigo)

--Usually effective as single agents


5-HT3 Receptor Antagonists
1. Most common adverse effects include?
2. Examples? 4

-dizziness, and

-Ondansetron (Zofran) **Most popular
-Granisetron (Kytril)
-Dolasetron (Anzemet)
-Palonosetron (Aloxi)


1. Most commonly used 5HT-3 Receptor Antagonist is what?
2. Approved use for who? 2
3. Preg cat?
4. Drug interactions? 3

2. Odansetron (Zofran)
Approved for use in children and adults
Pregnancy cat B
Drug interactions:
-caution for serotonin syndrome,
-QT prolongation,
-monitor liver function tests if prolonged use


What are the ways to administer zofran?4

1. Solution (Zofran Injection)
40 mg/20 mL (20 mL): $256.40

2. Tablet, orally-disintegrating (Ondansetron Oral)
4 mg (30): $668.78
8 mg (30): $1113.95

3. Tablet, orally-disintegrating (Zofran ODT Oral)
4 mg (30): $752.17
8 mg (30): $1252.86

4. Tablets (Ondansetron HCl Oral)
4 mg (30): $735.05
8 mg (30): $1217.42


Differential diagnosis of nausea/vomiting

1. Medications, toxicities
2. Infections (GI, ear)
3. Gut disorders
4. CNS causes
5. Endocrine
6. Misc.
-Post operative, cardiac, radiation, etc.


Nausea and vomiting associated with chemotherapy is treated differently (_____________ is a helpful adjunct)



Antibiotics for Treatment of Infectious Diarrhea: Empiric Antibiotic Therapy? 2

1. Oral Fluoroquinolone:
-Ciprofloxacin 500 mg PO twice daily,
-Norfloxacin 400 mg PO twice daily, or
-Levofloxacin 500 mg PO once daily (all for 3-5 days)

2. Oral Macrolides:
-Azithromycin 500 mg PO once daily for 3 days or
-Erythromycin 500 mg PO twice daily for 5 days (especially if fluoroquinolone resistance is suspected)


When would you reccommend pharmacologic therapy for the symptomatic treatment of diarrhea? 2

What would we use?

1. NO fever
2. NO blood in stool

Then can use an antimotility agent to decrease the number of stools per day


1. Bismuth subsalicylate (Pepto-Bismol) can be used for treatemant of what?
2. Considered what kind of drug?
3. MOA?

1. traveler’s diarrhea
2. Considered an absorbant
3. MOA: may exert its antidiarrheal action not only by stimulating absorption of fluid and electrolytes across the intestinal wall but also, when hydrolyzed to salicylic acid, by inhibiting synthesis of a prostaglandin responsible for intestinal inflammation and hypermotility.


Bismuth subsalicylate (Pepto-Bismol)
1.SE? 2
2. Cautions? 2
3. Contraindications? 2

1. Side effects
-Dark stools,
-black tongue

2. Cautions
-Do not take with other ASA components
-Can potentiate anticoagulants

3. Contraindications
-ASA allergy
-Infants and children


Symptomatic treatment of diarrhea: What meds? 3

1. Loperamide (Imodium)
2. Diphenoxylate/atropine (Lomotil)
3. Cholestyramine


Loperamide (Imodium)
1. Acts directly on what?
2. Which results in what? 5

1. MOA: acts directly on circular and longitudinal intestinal muscles, through the opioid receptor

-Inhibits peristalsis and prolongs transit time
-Reduces fecal volume, increases viscosity
-Diminishes fluid and electrolyte loss
-Demonstrates antisecretory activity
-Increases tone on the anal sphincter


Loperamide (Imodium)
1. Preg cat?
2. How and when to administer?
3. How long should you take it?
4. Avoid is what?

1. Pregnancy category C
2. 4 mg initially then 2 mg after each stool
3. Don’t use longer than a few days, if needed longer – reevaluate patient
4. Avoid if enteroinvasive organism is suspected


Loperamide (Imodium)
SE? 6

1. Abdominal pain
2. Abdominal distention
3. Constipation
4. Dry mouth
5. Nausea
6. Dizziness, drowsiness


Dipenoxylate/atropine (Lomotil)
1. MOA?
2. This results in? 3

1. MOA: Opiod antagonist and anticholinergic

-Inhibits peristalsis and slows intestinal motility
-Inhibits GI propulsion
-Prolongs the movement of fluid and electrolytes through the bowel


Dipenoxylate/atropine (Lomotil)
1. Preg cat?
2. How and when to administer?
3. Maintance dose?
4. Avoid if what?

1. Pregnancy Cat C
- Prescription
2. 2 tablets QID until diarrhea is controlled
3. Maintenance is 2 tabs per day
4. Avoid if enteroinvasive organism is suspected


Dipenoxylate/atropine (Lomotil)

1. Paralytic ileus, toxic megacolon
2. Drowsiness, dizziness
3. Euphoria
4. Tachycardia
5. Pruritis, urticaria
6. Respiratory depression
7. Anticholinergic effects


Cholestyramine (Questran)
1. Preg cat?
2. Useful for what? 2
3. How to administer?

1. Cholestyramine (Questran) Preg. Cat C
-Bile acid-binding agent used for hyperlipidemia
-Useful for the treatment of chronic diarrhea post cholecystectomy

3. 1 pack or scoop mixed with fluids or food BID


Cholestyramine (Questran)
SE 6

1. Constipation
2. Abdominal pain and bloating
3. Vomiting
4. Excessive flatulence, diarrhea
5. Weight loss
6. Decreases absorption of warfarin, thyroid hormones, digoxin and thiazide diuretics. These drugs should be administered 1 hour before or 4-6 hours after the administration of cholestyramine.


Laxative step therapy?

1. First line
-Bulk forming or surfactant agents
2. Second line
-Saline or hyperosmotic laxatives
3. Third line
-Stimulant laxatives


First line pharmacotherapy for the treatment of constipation

1. Bulk forming agents
-Psyllium (Metamucil)
2. Ducosate derivatives
-Ducosate sodium (Colace)
3. Glycerin
-Suppository – most often used for infants


OTC bulk forming laxatives
(which is preferred?)

Not for pts with what?

1. Metamucil (psyllium)
-preferred agent as it is the most physiologic
2. Fibercon (Polycarbophil)
3. Citrucel (methylcellulose)
4. Benefiber (wheat dextrin)

Powder and chewables
Not for patients with Celiac


Bulk forming agents:
1. Not absorbed how?
2. MOA? 3

1. Not systemically absorbed
-Bind to the fecal contents and pull water into the stool
-Softens and lubricates the stool
-Increased water in the stool makes it swell and increase in size – stimulates movement of the intestines


Bulk forming agents:
1. Onset of action?
2. Take with what?

1. Onset of action 12-24 hours but may take up to 3 days for the full effect
2. Take with at least 8 ounces of water


Bulk forming agents:
(most common side affect)

1. Most common side effect is flatulence
2. Bloating
3. Abdominal cramping
4. Excessive use can cause nausea and vomiting


Contraindications for bulk forming agents? 4

Caution in who?

1. Esophageal strictures
2. GI ulcerations
3. Strictures anywhere along the GI tract
4. Celiac patients need a specific gluten free formulation

CAUTION in DM: some contain up to 20 g carbohydrates per serving
Metamucil has a sugar free formula


Drug interactions with bulk forming agents?

Fibercon can decrease absorption of tetracycline and quinolones


Ducosate derivatives
1. What kind of laxative?
2. MOA? 2
3. Two types?

1. Surfactant laxatives
-Reduces the surface tension of the liquid contents of the bowel
-Commonly referred to as “stool softeners”

-Ducosate sodium (Colace) 50-500mg/day
Usual dose 100 mg qday to bid
-Ducosate calcium (Surfak)


Surfactant laxatives
1. Use for what kind of pts?
2. What kind of treatment?
3. absorption?
4. Combining with what helps promote defecation?

1. Use for patients who should not strain with bowel movements and for those on narcotics
2. Only prevent constipation – don’t treat
3. No systemic absorption
4. Combining with fiber based laxatives helps promote defecation


Surfactant laxatives

1. Most common SE is stomach upset
2. Mild abdominal cramping
3. Diarrhea

Overall – very well tolerated


Second line therapy
for constipation? 4

1. Phillips Milk of Magnesia
2. Magnesium sulfate (Epsom salt)
3. Lactulose
4. Sorbitol


Magnesium hydroxide (Milk of magnesia)
1. Is what kind of laxative?
2. MOA? 2
3. Used for what?
4. What is a concern for excessive use?
5. Avoid in who?
6. SE? 2

1. Saline laxative
-Draws water into the bowel through osmosis
-Increases intraluminal pressure & motility

3. Used for more rapid onset of action
4. Dehydration is a concern if excessive use
5. Avoid if renal dysfunction and elderly
6. SE: GI upset, diarrhea


Lactulose (Kristalose) or sorbitol
1. When do we use it?
2. What kind of laxative?
3. Use with caution in who?

1. Use if failed bulk forming agents, and failure of magnesium hydroxide (MOM)

2. Hyperosmotic laxatives

3. Use with caution in diabetics
Solution contains galactose and lactose


Lactulose (Kristalose) and sorbitol
1. MOA?
2. Can be given how?
3. SE? 3

- Metabolized to solutes and increase osmotic pressure by drawing in fluid from less concentrated areas
- Increased pressure stimulates intestinal motility

2. Can be given PO or as an enema

3. SE: GI upset, diarrhea, flatulence


Third line therapy

1. Stimulant laxatives
2. Mineral oil
3. Sodium biphosphates
4. Magnesium citrate
5. Castor oil


WHat are the stimulant lax? 2

1. Senna (Senokot)
2. Bisacodyl (Dulcolax)


Stimulant laxatives
1. For what kind of use?
2. MOA? 2
3. Onset of action? 2

1. Not for long term use
-Increase peristalsis through direct effects on the smooth muscle of the intestines
-Promote fluid accumulation in the colon and small intestine

3. Onset of action
15 min – 2 hrs PR
6-10 hrs PO


Stimulant laxatives
1. SE? 2
2. Complications? 1
3. Contraindications? 2

1. SE:
-abdominal cramping

2. Rectal fissures and hemorrhoids can be exacerbated

3. Contraindications:
-surgical abdomen,
-fecal impaction


Sodium phosphate
1. Can be administered how?
2. Can cause what problem?
3. Used as bowel prep for?
4. MOA?

-Fleet enema
-Fleet Phospho-soda

2. Can cause electrolyte disturbances

3. Can be used as bowel prep for endoscopy procedures

4. Osmotic effect in the small intestine by drawing water into the lumen of the gut, producing distention and promoting peristalsis and evacuation of the bowel


Sodium phosphate BBW?

Oral (BB warning for nephrotoxicity)


Magnesium citrate (Citroma)
1. Describe its onset?
2. Used for what?

1. Rapid onset of action
2. Can be used for bowel prep for endoscopy procedures


Polyethylene glycol electrolyte solution (Golytely)
1. What kind of laxative?
2. Used for?
3. SE? 7

1. Powerful osmotic laxative
2. Used for bowel prep for endoscopic procedures

3. Side effects
-Sleep disorder,
-Increased thirst,
-abdominal distention and pain
-Anorectal pain,
-bloating, nausea