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Summer pharm 4 > Motility d/o > Flashcards

Motility d/o Flashcards

1
Q

What are prokinetics

A

Drugs that selectively stimulate gut motor function

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2
Q

Explain the enteric nervous system

A

Serotonin is released from EC cells in gut
Distention stimulates intrinsic primary and extrinsic primary afferent neurons
Submucosal IPAN activate enteric neurons responsible for peristalsis and secretory reflex
5HT4 receptors release ACh and promote reflex activity

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3
Q

What drugs stimulate GI motility (prokinetics)

A

Cholinomimetics
Metoclopramide, Domperidone
Macrolides

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4
Q

What are the cholinomimetic agents

A

Bethanecol: stimulates M3 receptors on muscle and myenteric plexus. Tx GERD and gastroparesis
Neostigmine:ACh inhibitor, enhances gastric, small intestine, and colonic emptying

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5
Q

What are ADE of cholinomimetics

A 
excess salivation 
nausea 
vomiting 
diarrhea 
bradycardia 
(cholinergics; SLUDGE)
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6
Q

Cholinomimetics can be used for

A

GERD: used w/ anti-secretory agents if w/ regurg
Impaired gastric emptying: post-op, diabetic gastroparesis, promote advancement of NG tube
NUD: Sx improvement
Prevent vomiting: metoclopramide

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7
Q

What id Domperidone

A

Dopamine antagonist/cholinomimetic used in Canada (not FDA approved in US) to promote postpartum lactation

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8
Q

What is Metoclopramide

A

Dopamine antagonist with prokinetic mechanisms
Inhibit cholinergic smooth muscle stimulation
Increase esophageal peristaltic amplitude
Increase LES pressure
Enhance gastric emptying
-no effect on small or large intestine

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9
Q

How does metoclopramide help nausea and emesis

A

Blocks D2 receptor in the chemoreceptor trigger zone of the medulla

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10
Q

ADE of metoclopramide are

A

CNS: restless, drowsy, insomnia, anxiety, agitation
EPS: dystonia, akathisia, parkinsonian features
Tardive dyskinesia
Elevated PRL: galactorrhea, gynecomastia, impotence, menstrual disorders

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11
Q

How does erythromycin (macrolide) affect motility

A

Directly stimulate motilin receptors on GI smooth muscle
Benefits gastroparesis but tolerance develops fast
Can also be used for an upper GI bleed to empty stomach of blood prior to EGD

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12
Q

What meds have an ADE of constipation

A 
Analgesics 
Antihistamines, antiparkinsons, phenothiazine, TCA 
Antacids w/ calcium carbonate or aluminum hydroxide 
Barium sulfate 
CCB
Clonidine 
Diuretics 
NSAIDs
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13
Q

Intermittent constipation is best prevented with

A

high fiber diet
adequate fluid intake
regular exercise
going to the bathroom when you need to

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14
Q

If you do not have a specific Dx (and Tx) how do you treat constipation

A 
Diet mod (increase fiber) 
Add osmotic laxative (PEG) 2-4 wks 
Add stimulant laxative 
Lubiprostone 
Linaclotide 
Opioid antagonists if opioid induced
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15
Q

What are some laxatives you can use

A 
Bulk forming 
Stool surfactant agents (softeners)  
Osmotic laxative: PEG 
Stimulants: senna, cascara, bisacodyl 
Cl channel activator: Lubiprostone 
Guanylate cyclase C agonist: Linaclotide 
Serotonin agonist: Tegaserod
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16
Q

List agents that soften stool in 1-3 days

A

Osmotic laxatives: psyllium, polycarbophi, methylcellulose
Emollients: Docusate
PEG: Lactulose, sorbitol

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17
Q

List agents that cause soft semi-fluid stool evac in 6-12 hours

A

Bisacodyl
Senna
Mag sulfate

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18
Q

List agents that cause watery evacuation in 1-6 hours

A

Mag citrate

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19
Q

What are bulk forming laxatives

A

Indigestable hydrophilic colloids that absorb water and cause a bulky, emollient gel that distends the colon and promotes peristalsis
Natural: Psyllium, Methylcellulose (bloating and gas)
Synthetic: polycarbophil

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20
Q

What are stool surfactant agents

A 
Soften stool material by mixing aqueous and fatty materials within intestine 
Docusate (oral or enema) 
Mineral oil (clear viscous oil that lubricates stool but retards water absorption)
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21
Q

What is mineral oil used for

A

to prevent fecal impaction in young kids and debilitated adults
CAUTION: aspiration can lead to lipid pneumonitis
If used long term, can impair A, D, E, K absorption

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22
Q

What are osmotic laxatives

A

Soluble but not absorbable compounds resulting in increased stool liquidity
Colon normally can’t concentrate or dilute fecal fluid bc fecal water is isotonic

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23
Q

What are non-absorbable sugars or salts

A 
Mag hydroxide (milk of magnesia)-osmotic laxative to Tx acute constipation and prevent chronic 
Sorbitol, Lactulose: prevent or treat chronic constipation. sugars are metabolized by colon bacteria and produce flatus and cramps
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24
Q

Use Milk of magnesia cautiously long term in

A

pts with renal insufficiency, risk of hypermagnesemia

25
Q

What are purgatives

A

Cause rapid water movement into distal small bowel and colon

Mag citrate and Sodium phosphate: empty bowel in 1-3 hours. Stay hydrated!

26
Q

What are some ADE of sodium phosphate

A

Hyperphosphatemia, Hypernatremia
Hypokalemia, Hyocalcemia
-These can cause arrhythmias or acute renal failure (calcium phonphate deposits in the renal tubules

27
Q

Who should you NOT use sodium phosphate in

A

Elderly
Renal insufficiency
Cardiac disease
Unable to maintain adequate hydration during bowel prep

28
Q

What is PEG (polyethylene Glycol)

A

Balanced, isotonic sln made of non-absorbable sugar (PEG) with sodium sulfate/chloride/bicarb, or potassium chloride
Designed so NO significant intravascular fluid or electrolyte shifts occur= Safe for all patients! No cramps or gas!

29
Q

What can PEG be used for

A

Bowel prep: ingest rapidly (2-4L over 2-4 hours)

Prevent chronic constipation: mix smaller doses w/ water or juice

30
Q

What are cathartics

A

Stimulant laxatives that induce BM by directly stimulating enteric nervous system, colon electrolyte & fluid secretion

31
Q

Who are cathartics good for

A

Long term treatment is neurologically impaired, and bed bound patients in long term care facilities

32
Q

Can laxatives be used long term

A

Long term use is controversial; new studies say it’s ok because it is nerve damage that causes constipation, not using laxatives
BUT, if used long term, still need to monitor ADE

33
Q

What are Anthraquinone derivatives

A

Aloe, Senna, Cascara (natral plants)

They are poorly absorbed, undergo hydrolysis in the colon and produce BM in 6-12 hours (PO) or in 2 hours (per rectum)

34
Q

Chronic use of anthraquinones causes

A

brown pigmentation of the colon (melanosis coli)

They may be carcinogenic, but no studies prove relation to CRC

35
Q

Senna is used frequently in those that

A

Have opioid induced constipation

36
Q

What is Bisacodyl (ducolax)

A

Diphenylmethane derivative to treat chronic constipation
Used with PEG solutions as bowel prep prior to colonoscopy
Induces BM in 6-10 hours (PO) or 30-60 min (per rectum)
Safe for short and long term use bc of minimal systemic absorption

37
Q

How do opioids cause constipation

A

They decrease intestinal motility leading to prolonged transit time and increased absorption of fecal water

38
Q

What are the two selective agents of the mu-opioid receptor

A

Methylnaltrexone bromide
Alvimopan and Naloxegol
-They do not cross the BBB
-Inhibit peripheral mu receptors w/o impacting analgesic effects w/in the CNS

39
Q

What are the agents used in opioid induced constipation

A

Methylnaltrexone: approved for those receiving palliative care for advanced illness.
Alvimopan: short term use in post-op ileus in hospitalized pts s/p bowel resection. 7 days max.
Naloxegol: any opioid induced constipation

40
Q

ADE of mu receptor antagonists are

A

Methylnaltrecone: Adjust if CrCl <30
Alvimpoan: cardiovascular toxicity
Naloxegol: Adjust dose if CrCl <60. Avoid if w/ hepatic impairment. CI if w/ GI obstruction

41
Q

Treatment goals when treating diarrhea

A 
Manage diet 
Prevent excess whater, electrolyte, and acid base disturbances 
Provide Sx relief 
Treat curab;e causes 
Manage secondary disorders
42
Q

Define fever levels

A

PO: 100.4
Axillary: 1 degree lower
Rectal: 1 degree higher

43
Q

What are key points that spark clinical controversy in regards to diarrhea

A

Most recommend no solid food or dairy for 24 hours if w/ acute diarrhea
But withholding food is not appropriate in pts / no signs of severe dehydration
Osmotic diarrhea, food may control problem
If it is secretory, diarrhea will persist
If w/ N/V, eat low residue diet for 24 hours. if vomiting persists and not controlled w/ antiemetics, NPO

44
Q

What is in oral rehydration solutions

A

Carbs
Calories
Na, K, Cl, citrate, bicarb
*Listen to slide 34?

45
Q

What are some antidiarrheals

A

Antimotility: opioid agonists
Adsorbents: Kaolin pectin, polycrbophil, attapulgite
Antisecretory: colloidal bismuth, bile salt binding resins, octreotide
Bacterial replacement and enzymes

46
Q

Who should NOT use antidiarrheals

A 
Bloody diarrhea 
High fever 
Systemic toxicity 
-risk of worsening underlying condition 
-d/c in pts who's diarrhea is worsening despite therapy
47
Q

How do opioid agonists act as antidiarrheals

A

Increase colonic phasic segmentation activity by inhibiting presynaptic cholinergic nerves in myenteric plexus= increased fecal colonic transit time and fecal water absorption

48
Q

What are the opioid agonist antidiarrheals

A

Loperamide: does not cross BBB. Not an analgesic, no addiction potential. No tolerance reported (non-Rx)
Diphenopxylate: Rx. No analgesics in regular dose. High dose has CNS ADE. Prolonged use can lead to dependence. Some formulations have atropine in them to discourage overuse. (atropine also an anticholinergic)

49
Q

What do adsorbent antidiarrheals do

A

Adsorb nutrients, toxins, drugs, and digestive juices. like sponges

50
Q

Colloidal bismuth compounds are

A

Mucosally protective

51
Q

Who are bile acid binding resins used for

A

They are normally absorbed in the terminal ileum

In those w/ terminal ileum d/o (crohn’s), they have malabsorption of bile salts= colonic secretory diarrhea

52
Q

What are the bile acid binding resins

A

Cholestyramine, colestipol, colesevelam: decrease diarrhea 2/2 excess fecal bile acids

53
Q

ADE of bile acid binding resins are

A 
Bloating 
flatulence 
constipation 
fecal impaction 
Fat malabsorption if they already have low circulating bile acids
54
Q

Do bile acid binding resins interact with other drugs

A

cholestyramine and colestipol bind a few drugs and reduce their absorption. Wait 2 hours to admin other drugs
colesevelam does not

55
Q

What is octreotide

A

Somatostatin;
Inhibits secretion of hormones and transmitters (gastrin, CCK, glucagon, GH, insulin, secretin, 5HT)
Reduce intestinal and pancreatic fluid secretion
Slow GI motility and inhibit gallbladder contraction
Reduce portal and splanchnic blood flow
Inhibit secretion of other ant pit hormones

56
Q

Octreotide’s usefulness is limited by

A

it’s short half life (3 minutes) when given IV

57
Q

Octreotide is used clinically for

A

Inhibiting endocrine tumor effects (secretory diarrhea, flushing, and wheezing 2/2 carcinoid or VIPoma)
Other causes of diarrhea (low dose stimulates motility but high dose inhibits): Vagotomy, dumping syndrome, short bowel syndrome, AIDS
-also: inhibit pancreatic secretion value in patients w/ pancreatic fistula, Tx pit tumors and GI bleeding

58
Q

ADE of octreotide are

A

Steatorrhea
Nausea, abdominal pain, flatulence, diarrhea
Altered fat absorption (inhibits gallbladder contractility)
Hyperglycemia (sometimes hypo-)
Hypothyroid w/ prolonged use Bradycardia

Summer pharm 4 (14 decks)

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