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PCOL Cumulative Final > Final GI > Flashcards

Final GI Flashcards

1
Q

5-HT3 Receptor Antagonists: Agents

A

Palonosetron 5-HT3A CYP3A4

Dolasetron 5-HT3B CYP3A4

Granisetron 5-HT3A, 5-HT3B, 5-HT3C CYP3A4

Ondansetron 5-HT3B, 5-HT1B, 5-HT1C CYP3A4

Please Don’t Grow Old

-setron

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2
Q

5-HT3 Receptor Antagonists: MOA

A

MOA: Selective

Central blockade of CTZ and vomiting center

Peripheral Blockade on intestinal vagal and spinal afferent nerves-> drives antiemetic benefit

No affinity for H1, M1, or D2 receptor

Ondansetron, Granisetron, Dolasetron, Palonosetron**

Equal efficacy at equipotent doses

Palonosetron has longer t1/2 = 40 Hrs greater binding affinity (IV)

Cornerstone for chemotherapy-induced N/V

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3
Q

5-HT3 Receptor Antagonists: ADEs

A

Generally well tolerated

HA, Dizziness, Constipation

Small but statistically significant prolongation of the QTc interval

Primarily by K+ channel blockade

-Check for what medications?

Least common with Palonosetron

Serotonin Syndrome (rare)

What meds?

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4
Q

Dopamine (D2) Receptor Antagonists: Agents

A

Prochlorperazine / Promethazine D2, M1, H1, a-Adrenergic

Olanzapine D2, 5-HT1c, 5-HT3,

Trimethobenzamide D2, H1 (weak)

Metoclopramide D2, 5-HT3 (weak)

Prokinetic action-> also used for gastroparesis

ADEs: Dystonia, akathisia, parkinsonian, sedation, hyperprolactinemia, hypotension, dry mouth, etc.

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5
Q

Neurokinin-1 (NK1) Receptor Antagonists: MOA

A

MOA: Central blockade of the NK1 receptors in CTZ

Blocks binding of substance P

Aprepitant, Netupitant, Rolapitant** (PO)**

Netupitant & Rolapitant t1/2= 90&180 HRs respectively

Netupitant/Palonosetron (Akynzeo)

Fosaprepitant** (IV)**

Converted to aprepitant 30 minutes after infusion

Used for prevention of CINV along with 5-HT3 antagonists and corticosteroids

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6
Q

Neurokinin-1 (NK1) Receptor Antagonists: ADEs

A

Well tolerated

Fatigue, dizziness

CYP 3A4 substrate and inhibitor

Concomitant use of CYP 3A4 inhibitors can cause toxicity

Aprepitant + Warfarin = decreased INR (Leads to clotting)

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7
Q

MISC Anti-emetics

A

Antihistamines and antimuscarinic drugs

Dimenhydrinate, diphenhydramine, meclizine, etc

-H1 > M1

Scopolamine (patch)

-M1 > H1

Ginger - 5-HT3 antagonism

Mirtazapine - 5-HT3 antagonism, H1 antagonism

Cannabinoids (CIII)

Dronabinol

Nabilone

-THC reduces vomiting by binding to CB1 receptors

Use for refractory N/V induced by Chemotherapy

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8
Q

Constipation defined

A

A decrease in frequency of fecal elimination characterized by the difficult passage of hard, dry stools

PTs will commonly report the following signs and symptoms of constipation:

Straining to pass stool

The passage of hard, dry stool

Feelings of incomplete evacuation

Passage of small stools

Bloating

Decreased Stool frequency

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9
Q

Anti-constipation overview

A

Watery evacuation within 1-6 hours

Magnesium citrate, hydroxide & sulfate (high-dose)

Sodium phosphates

Bisacodyl (rectal)

Semi-fluid stool in 6-12 hours

Bisacodyl (oral)

Senna

Magnesium sulfate (high dose)

Softening of feces in 1-3 days

Bulk-forming agents

Emollients

PEG 3350

Mineral oil

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10
Q

OTC Laxatives - Bulk Forming

A

MOA: Dissolves or swells in the intestinal fluid, forming emollient gels that facilitate the passage of intestinal contents and stimulate peristalsis

OTC products:

Methylcellulose

Polycarbophil

Psyllium

DOC for constipation, good for PTs on low fiber diet

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11
Q

OTC Laxatives: Emollients

A

MOA: Increases the wetting efficacy of intestinal fluid and facilitate a mixture of aqueous and fatty substances to soften fecal mass

OTC product:​ Docusate sodium

Good for PTs with c/o dry stools, straining when defecating

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12
Q

OTC Laxatives: Lubricants

A

MOA: Soften fecal contents by coating them, thereby preventing colonic reabsorption of fecal water

OTC Products: Mineral oil

Saftey concern of lipid pneumonia

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13
Q

OTC Laxatives: Saline Laxatives

A

MOA: Draws water into the intestine, increasing intraluminal pressure, which acts as a stimulus to increase intestinal motility

OTC products:

Magnesium citrate

Magnesium hydroxide

Sodium phosphate/diphosphate

Screen elders and those with renal and cardiac disease

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14
Q

OTC Laxatives: Hyperosmotic Laxatives

A

MOA: Draws water into rectum to stimulate a bowel movement

OTC Products: Glycerine, Polyethylene Glycol 3350

-Take with 4-8 ounces of water

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15
Q

OTC Laxatives: Stimulant Laxatives

A

MOA: Increase the propulsive peristaltic activity of the intestine by local irritation of the mucosa. Stimulates the secretion of water and electrolytes in the large intestine

OTC products:

Senna

Bisacodyl

-Can cause electrolyte and fluid deficiencies along with malabsorption

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16
Q

Laxative Abuse

A

Utilized for weight loss

Rush food through the GI tract before absorption

Mainly-> loss of water, electrolytes, and minerals

Na+, K+, Mg+, and PO4

Tremors, weakness, blurry vision, fainting, kidney injury, metabolic alkalosis or arrythmias

Abuse may lead to dependence

Chronic abuse may cause “lazy” colon infection, INC risk of colon cancer

When to suspect

More common in women, eating disorders, PMH inconsistency, altered diarrhea constipation complaints

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17
Q

Opioid-Induced Constipation (OIC)

A

Opioids

Delay Gastric emptying

Interrupt Bowel Peristalsis

Reduce Intestinal Secretion of fluid

-Less Bowel Movements, possible drier stools

Predictable ADE-> PTs do NOT develop tolerance

Traditional laxatives used first-line due to:

Cost

Accessibility

Saftey Profile

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18
Q

OIC Agents (2nd Line)

A

Methylnaltrexone

Alvimopan

MOA: Peripheral acting u opioid receptor antagonists

MInimal Absorption in the GIT

Does not cross the BBB

ADEs: abdominal pain and/or distention, diarrhea, HA, chills

DO not use methylnaltrexone if PY has HX of GI obstruction

Long term use of Alvimopan increases risk of MI

-Short term use only

19
Q

Chronic Constipation 1

A

Lubiprostone

Bicyclic fatty acid derived from prostaglandin E1

MOA: Activates chloride channel-2 (CIC-2) in GI epithelial cells -> efflux of Cl- into lumen of GI tract -> followed by efflux of Na2 -> followed by water

  • Increase fluid secretion
  • Increases intestinal transport

ADEs: Nausea (31%), diarrhea, abdominal pain, and distention, HA

20
Q

Chronic Constipation Linaclotide

A

Linaclotide

MOA: Activates guanylate cyclase in response to a meal -> increases -> cGMP -> stimulates chloride, sodium bicarbonate, and water secretion into intestinal lumen

Also activates colonic sensory and motor neurons

-Reduces abdominal pain and increases smooth muscle contraction

ADEs: diarrhea, dehydration, dizziness, hypokalemia

-Black Box Warning: Serious dhydration - Do not use < 18 Y/O

21
Q

Diarrhea - Bismuth Subsalicylate

A

Bismuth Subsalicylate (pepto)

MOA: Reactis with HCL to form bismuth oxychloride and salicylic acid

Bismuth -> direct antimicrobial effects (H. Pylori)

Salicylic acid -> inhibits chloride secretion in intestine to reduce liquid content of stools

Avoid if documented allergy or sensitivity to ASA

Do not use in children <12 Y/O (Reye’s syndrome)

ADEs: Blackening of tongue and stools (benign), tinnitus, dry stools, confusion

22
Q

Diarrhea - Loperamide

A

Loperamide (Immodium)

MOA: Synthetic, peripheral u opioid agonist that stimulates receptors located in the intestinal circular muscles

Slows intestinal contractions

Inhibits secretion of electrolytes and water

No tolerance has been reported

ADEs: Dizziness, mild constipation, Abdominal pain/distention

No CNS effects at standard doses

23
Q

Loperamide Abuse

A

At high dose in a Mu-agonist, but also leads to cardiac arrhythmias/syncope/arrest

Suspect overdose when:

Fainting

Tachycardia

Unresponsiveness

Fatal at 4-100 x dose (8mg OTC, 16mg RX)

FDA -> request limited doses per package from manufactureres

24
Q

Diarrhea - Diphenoxylate/Atropine

A

Diphenoxylate/Atropine

Diphenoxylate is a peripheral u opioid agonist

CNS effects at high dose

Prolonged use can lead to tolerance

Co-formulated with small doses of atropine

  1. 5 mg diphenoxylate with .025 mg of atropine per tablet or teaspoonful
    - Discourages OD
    - Anticholinergic properties can constribute to antidiarrheal effect

RX only

Federally classified as a controlled supstance CV

ADEs: dry mouth, constipation,

Euphoria, respiratory depression (high dose)

25
Antacids
**MOA: Neutralizes pH** **Provides Symptomatic relief only-\> appropriate for episodic GERD, "sour stomach", acid indigestion** **Products contain at least one of the following salts** Magnesium, Aluminum, Calcium Carbonate, Sodium Bicarbonate **Liquids have faster onset of action vs Pills** **Side effects are determined by the salt form** Magnesium -\> diarrhea Calcium, Aluminium -\> constipation Sodium -\> Flatulence/belching, fluid retention **Watch for Renal insufficiency** **_No preventative, only response, action w/in 5 minutes duration 20-30 minutes_**
26
Antacids ADE/Agents
**Can Decrease absorption of other drugs** FQ, Tetracycline, Iron, Itraconazole, etc. -Seperate doses by 2-4 hours **Calcium Carbonate (Tums / rolaids)** **Sodium Bicarbonate (Alka-seltzer - 500 mg Sodium per tab)** **Magnesium & Aluminum hydroxide (Maalox advanced, Mylanta, Gaviscon)**
27
Histamine2 - Receptor antagonist (H2RA)
**MOA: Reversibly decreases fasting and food-stimulated acid secretion by inhibiting histamine on the H2 receptor of the parietal cell** **Indicated for the treatment of mild-moderate, infrequent, episodic heartburn** 60-70% acid suppression **Cimetidine, Ranitidine, famotidine, have extensive first pass effect** Nizatidine minimal first pass
28
Proton Pump Inhibitors (PPI)
**MOA: Irreversibly inactivates the hydrogen-potassium adenosine triphosphate (H+/K+-ATPase) "proton" pump resulting in impairment of acid secretion** Pro-drug is protected by enteric coating (EC) In the intestinal lumen, the EC dissolves and the drug is released and absorbed -\> carried to the parietal cell for activation Forms strong covalent bonds with proton pump **Most potent inhibitors of acid suppression** 90-98% acid suppressed
29
PPI Agents
**Omeprazole OELDPR -prazole** **Esomeprazole** **Lansoprazole** **Dexlansoprazole** **Pantoprazole** **Rabeprazole** Equally Efficacious **Buioavailability decreased with food** **3-4 days for maximal suppression of acid, not for acute relief**
30
PPI ADE/DDI
**ADEs: D/HA, abdominal pain, B12 def, Reduced absorption of Iron/Ca/Mg, osteoporosis, fractures, CAP, c. difficile (others?)** **Do not abruptly stop - Taper to avoid rebound acid secretion** **DDIs: Ketoconazole, itraconazole, atazanavir, rilpivirine, Calcium carbonate, iron salts** Omeprazole + clopidogrel = therapeutic failure of clopidogrel
31
Sucralfate
**Sucrose + complexed aluminum hydroxide** Mixes with HCL to form viscous paste that bindfs directly to ulcers and erosions -Physical barrier to protect stomach lining Stimulates mucosal prostaglandin and bicarbonate secretion **~3% systemically absorbed -\> very few ADEs** Constipation (aluminum) -Aluminum tox can occur in renal disease **Limited clinical utility**
32
Misoprostal
**PGE1 analog** Increases mucosal and bicarbonate secretion Enhances mucosal blood flow -Stomach protectant **Used clinically for prevention of NSAID-related ulcers or labor induction (OB/GYN)** **Comes in combination product with diclofenac sodium** **ADEs: D, enhanced uterine contractions** **_Do not take if pregnant_**
33
Inflammatory Bowel disease
**Disease** **of Chronic relapsing inflammation** **Idiopathic causes** Genetic susc Environment Microbial factor Immune response
34
Ulcerative colitis
**Disease involvement: Colon and/or rectum** Proctitis = inflammation of the rectum **Continuous inflammation of the colon** **Affects the innermost lining of the colon**
35
Crohn's Disease
**Disease involvement: entire GIT** **Mix of Healthy and inflamed areas** **Can affect all layers of the bowel walls**
36
Aminosalicylates
**MOA: Largely unknown** Interferes with production of inflammatory cytokines Modulates inflammatory mediators derived from COX and lipoxygenase **Meant to work typically with minimal systemic effects** Efficacy is dependent on achieving high concentration at the site of disease **_Contraindicated in those with Salicylate allergy_**
37
Sites of 5 ASA release from different drug formulations
38
5-ASA Agents
**Mesalamine (5-ASA)** **PO** (do not crush) - **Time release**: Pentasa - **pH-dependent release**: Asacol/Aprisco/Lialda **Enema**: Rowasa **Suppository**: Canasa **Preferred due to tolerability**
39
5-ASA Prodrug Agents
**_Given PO_** **Sulfasalazine** **Balasalazide** **Olsalazine**
40
Aminosalicylate ADEs
**Mesalamine:** Well tolerated -\> N/HA, Abdominal Pain **Olsalazine:** Secretory diarrhea **Sulfasalazine:** Most side effects due to sulfapyridine moiety Rash/hypersensitivity, photosensitivity, hemolytic anemia, folate def, pancreatitis, hepatitis -Monitor CBC LFT Avoid if sulfa Allergy Supplement with Folic Acid **DDIs: Meds that alter stomach pH (can alter dissolution)**
41
Corticosteroids
**Budesonide - PO** Synthetic analog of prednisolone pH controlled, delayed release - Entocort (pH 5.5) - Uceris (pH \>7) Extensively metabolized via CYP3A4 - watch for potent inhibitors **Hydrocortisone enema/foam/suppository** Rectum, distal colon -15 to 30% absorbed systemically **Systemic steroids (prednisone, prednisolone, etc)** For acute flares -\> try to minimize long-term exposure
42
IBS - Thiopurines
**MOA: Purine antagonist -\> inhibit DNA/RNA synthesis -\> decreased T-Cell Function -\> immunosuppresion** 3-6 months to clinical benefits **Azathioprine -PO** Pro-drug metabolized to 6-mercaptopurine (6-MP) **6-mercaptopurine -PO** Active metabolite of Azathioprine **ADEs: N/V, bone marrow suppression (leukopenia), _hepatoxicity_** **DDI: allopurinol febuxostat (gout)**
43
IBS - Other immunosuppressants
**Methotrexate (MTX) - IM/SQ** MOA: Inhibits dihydrofolate reductase-\> reduces purine metabolism -\> inhibits DNA synthesis, repair and replication ADEs: hepatotoxicity, myelosuppression, nausea **Cyclosporine -IV** MOA: Calcineurin inhibitor-\> decreases transcription of IL-2, TNF-alpha, IL-3, IL-4, etc. ADEs: nephrotoxicity, HTN

PCOL Cumulative Final (14 decks)

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