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Adv Pharm > Chapter 66: Other GI Drugs > Flashcards

Chapter 66: Other GI Drugs Flashcards

1
Q

GI drugs

A

Antiemetics

Antidiarrheals

Drugs for irritable bowel syndrome

Drugs for inflammatory bowel disease

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2
Q

Antiemetics

A

Given to suppress nausea and vomiting

Emetic response
Complex reflex that occurs after activation of vomiting center in the medulla oblongata

Several types of receptors involved in emetic response:
Serotonin, glucocorticoids, substance P, neurokinin1, dopamine, acetylcholine, histamine
Many antiemetics interact with one or more of the receptors

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3
Q

Antiemetics: Serotonin receptor antagonists

A

Granisetron, dolasetron, palonosetron

Ondansetron [Zofran]

First approved for chemotherapy-induced nausea and vomiting (CINV)

Also used to prevent nausea and vomiting associated with radiotherapy and anesthesia

Blocks type 3 serotonin receptors on afferent vagal nerve

More effective when used with dexamethasone

Adverse effects: Headache, diarrhea, dizziness, prolonged QT interval, risk of torsades de pointes

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4
Q

Antiemetic: Glucocorticoids

A

Unknown mechanism of action (MOA) as antiemetic

Methylprednisolone

Dexamethasone

Commonly used to suppress CINV; however, this is not an application approved by the U.S. Food and Drug Administration (FDA)

Effective alone and in combination with antiemetics

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5
Q

Antiemetics: Substance P/neurokinin1 antagonists

A

Aprepitant

Blocks neurokinin1-type receptors (for substance P) in the chemoreceptor trigger zone (CTZ)

Prevents postoperative nausea/vomiting and CINV

Prolonged duration of action

Adverse effects: Generally well tolerated

Drug interaction: CYP3A4, CYP2D6

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6
Q

Antiemetics: Benzo

A

Lorazepam [Ativan]

Used in combination regimens to suppress CINV

Three primary benefits:
Sedation
Suppression of anticipatory emesis
Production of anterograde amnesia

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7
Q

Antiemetics: dopamine antagonist, Phenothiazines: Prochlorperazine

A

Phenothiazines: Prochlorperazine

Block dopamine2 receptors in CTZ (chemo receptor trigger zone)

Surgery, cancer, chemotherapy, and toxins

Most widely used antiemetic in children despite ADR -respiratory depression and local tissue injury. Contraindicated in children under 2y and caution in children older

Side effects
Extrapyramidal reactions
Anticholinergic effects
Hypotension and sedation

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8
Q

Antiemetics: dopamine antagonists, Butyrophenones

A

Haloperidol [Haldol] and droperidol [Inapsine]

Block dopamine2 receptors in CTZ

Postoperative nausea/vomiting, chemotherapy emesis, radiation therapy, and toxins

Side effects
Similar to phenothiazines
May cause prolonged QT interval and fatal dysrhythmias
Electrocardiogram (ECG) before administration

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9
Q

Antiemetics: dopamine antagonists, Metoclopramide [Reglan]

A

Blocks dopamine receptors in CTZ

Postoperative nausea/vomiting, anticancer drug, opioids, toxins, radiation therapy

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10
Q

Antiemetics: canabinoids

A

Dronabinol [Marinol] and nabilone [Cesamet]

Related to marijuana

CINV

MOA with emesis unclear

Potential for abuse and psychotomimetic effects

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11
Q

Management of Chemotherapy- Induced Nausea and Vomiting: 3 times of vomiting

A

Anticipatory
Occurs before drugs are given
Acute
Onset within minutes to a few hours
Delayed
Onset 1 day or longer after drug administration

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12
Q

Management of Chemotherapy- Induced Nausea and Vomiting

A

Antiemetics are more effective in preventing CINV than in suppressing CINV in progress

Give before chemotherapy drugs

Monotherapy and combination therapy may be needed

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13
Q

Nausea and Vomiting of Pregnancy

A

Hyperemesis gravidarum: Dehydration, ketonuria, hypokalemia, and loss of 5% or more of body weight

Nondrug measures
Diet changes, relaxation measures

First-line therapy consists of a two-drug combination: Doxylamine plus vitamin B6

Others: Prochlorperazine, metoclopramide, and ondansetron. methylprednisolone may be tried as a last resort, but only after 10 weeks’ gestation

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14
Q

Drugs for Motion Sickness: scopolamine

A

Muscarinic antagonist

Side effects
Dry mouth
Blurred vision
Drowsiness

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15
Q

Drugs for Motion Sickness: antihistamines

A

Dimenhydrinate, meclizine, cyclizine

Considered anticholinergics; block receptors for acetylcholine and histamine

Side effects
Sedation (H1 receptor blocking)
Dry mouth, blurred vision, urinary retention, constipation (muscarinic receptor blocking)

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16
Q

Diarrhea

A

Characterized by stools of excessive volume and fluidity and increased frequency of defecation

Symptom of GI disease

Causes
Infection, maldigestion, inflammation, functional disorders of the bowel

Complications
Dehydration and electrolyte depletion

Management
Diagnosis and treatment of underlying disease
Replacement of lost water and salts
Relief of cramping
Reducing passage of unformed stools

Two major groups of antidiarrheals:
Specific antidiarrheal drugs
Nonspecific antidiarrheal drugs

17
Q

Opioids

A

Most effective antidiarrheal agents

Diphenoxylate, difenoxin, loperamide, paregoric, and opium tincture

Activate opioid receptors in GI tract
Reduce intestinal motility
Slow intestinal transit
Allow more fluid to be absorbed
Decrease secretion of fluid into small intestine and increase absorption of fluid and salt

Most commonly used: Diphenoxylate [Lomotil] and loperamide [Imodium]

18
Q

Diphenoxylate [Lomotil]

A

Formulated with atropine to discourage abuse

Opioid used only for diarrhea

High doses can elicit typical morphine-like subjective responses

19
Q

Loperamide

A

Structural analog of meperidine (opioids)

Used to treat diarrhea and to reduce the volume of discharge from ileostomies

Little or no potential for abuse

20
Q

Nonspecific Antidiarrheal Agents

A

Difenoxin

Paregoric

Opium tincture

Bismuth subsalicylate

Bulk-forming agents

Anticholinergic antispasmodics

21
Q

Management of Infectious Diarrhea

A

General considerations
Variety of bacteria and protozoa can be responsible
Infections are usually self-limited
Many cases require no treatment
Antibiotics should be used only when clearly indicated: Salmonella, Shigella, Campylobacter, or Clostridium infections

Traveler’s diarrhea
Escherichia coli: Usually self-limiting
Ciprofloxacin, norfloxacin

22
Q

Irritable Bowel Syndrome (IBS)

A

Most common disorder of GI tract
Affects 20% of Americans
Incidence in women is three times higher than in men

Characterized by cramping abdominal pain (may be severe) that cannot be explained by structural or chemical abnormalities

May occur with diarrhea, constipation, or both

Considered IBS when symptoms have been present for 12 weeks over the past year

23
Q

IBS tx

A

Four groups of drugs historically used
American College of Gastroenterology has concluded there is no proof of clinical benefit for most of these agents:
Antispasmodics
Bulk-forming agents
Antidiarrheals
Tricyclic antidepressants

Studies suggest that antibiotics or an acid suppressant may be effective for some patients

24
Q

Alosetron [Lotronex]

A

IBS specific drug

Potentially hazardous drug; approved for women only

GI toxicities can cause complicated constipation, leading to perforation and ischemic colitis

Risk management program

25
Q

Lubiprostone [Amitiza]

A

Approved for constipation-predominant IBS (IBS-C) in women age 18 years or older

Modest benefits

26
Q

Tegaserod [Zelnorm]

A

Short-term therapy of IBS-C and chronic idiopathic constipation (CIC) in women younger than age 55 years who are free of cardiovascular (CV) disease

27
Q

Inflammatory Bowel Disease (IBD)

A

Caused by exaggerated immune response to normal bowel flora

Crohn disease
Characterized by transmural inflammation
Usually affects terminal ileum (can affect all parts of GI tract)

Ulcerative colitis
Inflammation of the mucosa and submucosa of the colon and rectum
May cause rectal bleeding
May require hospitalization

28
Q

Drugs for IBD

A

Not curative; may control disease process

5-Aminosalicylates (sulfasalazine; 5-ASA)

Glucocorticoids (hydrocortisone)

Immunosuppressants (azathioprine)

Immunomodulators (infliximab)

Antibiotics (metronidazole)

29
Q

5-Aminosalicylates, Sulfasalazine [Azulfidine]

A

5-ASA reduces inflammation; it also suppresses prostaglandin synthesis and migration of inflammatory cells into affected region

Most effective against acute episodes of mild to moderate ulcerative colitis

30
Q

Glucocorticoids, Budesonide

A

Approved for mild to moderate Crohn disease that involves the ileum and ascending colon

Prolonged use of glucocorticoids can cause severe adverse effects, including adrenal suppression, osteoporosis, increased susceptibility to infection, and Cushing’s syndrome

31
Q

Immunosuppressants: Azathioprine [Imuran] and mercaptopurine [Purinethol]

A

Induce and maintain remission in both ulcerative colitis and Crohn disease

Onset of effects may be delayed for up to 6 months

Reserved for patients who have not responded to traditional therapy

Adverse effects are pancreatitis and neutropenia

32
Q

Immunomodulators: Infliximab [Remicade]

A

Monoclonal antibody designed to neutralize tumor necrosis factor (TNF), a key immunoinflammatory modulator

Moderate to severe Crohn disease and ulcerative colitis

33
Q

Antibiotics: Metronidazole [Flagyl] and ciprofloxacin [Cipro]

A

Crohn disease: Can help control symptoms

Ulcerative colitis: Antibiotics largely ineffective

Metronidazole [Flagyl]: Long-term therapy is required; prolonged use of high-dose metronidazole poses risk of peripheral neuropathy

Ciprofloxacin [Cipro]: Highly effective in patients with mild or moderate Crohn disease

34
Q

Prokinetic Agents

A

Increase tone and motility of GI tract

GERD, CINV, diabetic gastroparesis

Metoclopramide [Reglan, Maxolon, Octamide]
Blocks receptors for dopamine and serotonin in the CTZ
Increases upper GI motility and suppresses emesis

Cisapride [Propulsid]

35
Q

Metoclopramide [Reglan]

A

Suppress emesis and increase upper GI motility

Therapeutic uses
PO: Diabetic gastroparesis and suppression of gastroesophageal reflux
IV: Suppression of postoperative nausea and vomiting, suppression of CINV, facilitation of small bowel intubation, and facilitation of radiologic examination of GI tract

Adverse effects
High-dose therapy: Sedation, diarrhea common
Long-term high-dose therapy: Can cause irreversible tardive dyskinesia (TD)

36
Q

Palifermin [Kepivance]

A

First drug approved for decreasing oral mucositis (OM)

Currently indicated only for patients with hematologic malignancies (can stimulate proliferation of malignant cells of nonhematologic origin)

Synthetic form of human keratinocyte growth factor (KGF)

Stimulates proliferation, differentiation, and migration of epithelial cells

37
Q

Pancreatic Enzymes

A

Deficiency of enzymes compromises digestion

Pancrelipase: Pancreatic enzyme for clinical use; mixture of lipases, amylases, and proteases prepared from hog pancreas

Can be sprinkled on food, can be taken as capsules

38
Q

Drugs Used to Dissolve Gallstones

A

Chenodiol (chenodeoxycholic acid)
Useful for radiolucent stones (not calcium)
Increases production of bile acids
Most successful in women with low cholesterol levels

Ursodiol (ursodeoxycholic acid)
Does not increase bile acids
Reduces cholesterol content of bile
Gradual dissolution of stones

39
Q

Anorectal Preparations

A

Symptomatic relief of hemorrhoids and other anorectal disorders
Local anesthetics
Hydrocortisone
Emollients
Astringents

Multiple formulations available

OTC

Adv Pharm (76 decks)

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