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GI Final > Drugs Affecting Motility > Flashcards

Drugs Affecting Motility Flashcards

1
Q

What are the 11 drug classes that affect motility?

A

SSRIs, Bulk Laxatives, Contact Cathartics, 5HT3 Receptor Antagonists, 5HT4 Receptor Agonists, Opiates, mu Receptor Antagonists, Dopamine D2 Receptor Antagonists, Tricyclic Antidepressants (TCAs), Atropine, Macrolides

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2
Q

What SSRIs do you need to know?

A

Fluoxetine, Paroxetine, Sertraline

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3
Q

What is the MOA for SSRIs?

A

Decrease reuptake of 5HT into EC cells which increases 5HT in synapse which increases afferent activity which increases peristalsis.

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4
Q

What is the therapeutic use for SSRIs?

A

Constipation - IBS

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5
Q

What Bulk Laxatives should you know?

A

Dietary fiber, Methylcellulose, Polycarbophil, Psyllilum

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6
Q

What is the MOA for Laxatives?

A

Attract water to the lumen and increase mass of stool (stool stablizer) which increases distention of the lumen and increases release of 5HT from EC cells which increases afferent activity and increases peristalsis

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7
Q

What are the therapeutic uses for Bulk Laxatives?

A

Diarrhea to dec. bowel movements, increase solid, decrease pain. Constipation to inc. bowel movements, decrease solid, decrease pain

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8
Q

What are the side effects of bulk laxatives?

A

Allergic, increase flatulence, increase obstruction

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9
Q

What are the limitations of bulk laxative use?

A

Peristaltic neurons must be functional, cause of constipation must be known.

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10
Q

What contact cathartics should you know?

A

Anthraquinone (cascara sagrada, danthron, senna), Bisacodyl (prodrug), Castror Oil

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11
Q

What is the MOA for Contact Cathartics?

A

Unknown. Possibly irritation leading to EC activity leading to increased release of 5HT from EC leading to increased afferent activity which means increased peristalsis.

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12
Q

What are the side effects of Contact Cathartics?

A

Long term: dependency and destruction of myenteric plexus, pigmentation of mucosa (melanosis coli).

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13
Q

What are the side effects of Castor Oil?

A

Dehydration, Electrolyte imbalance, uterine contractions

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14
Q

What is unique about Bisacodyl and Antraquinones?

A

Act on large intestine. Less potent.

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15
Q

What is unique about Castor Oil?

A

Acts on both large and small intestine. Short latency, extremely potent.

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16
Q

What 5HT3 Receptor Antagonist do you need to know?

A

Alosetron

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17
Q

What is the MOA for Alosetron?

A

Dec. afferent stimulation which leads to decreased peristalsis.

18
Q

What is the therapeutic use for Alosetron?

A

Diarrhea IBS (restricted ability)

19
Q

What are the side effects of Alosetron?

A

Constipation (30 percent, 10 percent must stop, 0.1 percent hospitalized). 0.3 percent will get Ischemic Colitis which is fatal.

20
Q

What should you know about Alosetron vs antiemetic 5HT3 receptor antagonists?

A

Alosetron has a longer duration of action than antiemetics.

21
Q

What 5HT4 receptor Agonists do you need to know?

A

Cisapride (5HT3 antag.)

Tegaserod (more selective)

22
Q

What is the MOA for 5HT4 receptor agonists?

A

5HT4 agonist causes increased release of NT from afferent neuron which increases peristalsis.

23
Q

What is the therapeutic use of Cisapride?

A

Diabetic gastroparesis - restricted availability

24
Q

What is the therapeutic use of Tegaserod?

A

Constipation IBS - restricted availability

25
Q

What are the 5HT4 Receptor Agonists side effects?

A

Cardiovascular toxicity which leads to long QT

26
Q

What Mu Receptor Antagonists do you need to know?

A

Alvimopan, Methylnaloxone.

27
Q

What is the MOA for Mu Receptor Antagonists?

A

Selective antagonist of mu receptor which leads to increased peristalsis.

28
Q

What is the therapeutic use for Alvimpan?

A

Short term, hospital only - Constipation caused by opiates.

29
Q

What is the therapeutic use for Methylnaloxone?

A

Long term palliative care. Constipation caused by opiates.

30
Q

What is the side effect of Alvimopan?

A

Increased risk of MI.

31
Q

What should you remember about mu receptor antagonists?

A

They don’t cross BBB.

32
Q

What Dopamine D2 Receptor Antagonists do you need to know?

A

Domperidone (not US) and Metoclopramide (US)

33
Q

What is the MOA for Dopamine D2 Receptor Antagonists?

A

Inhibit DA inhibition of cholinergic which increases ACh release and increases peristalsis. This increases motility in ENTIRE gut.

34
Q

What is the therapeutic use for Domperidone?

A

Compassionate use only (not in US). Impaired motility patients (esp. dec. gastric emptying)

35
Q

What is the therapeutic use for Metoclopramide?

A

Anti-emetic

36
Q

What side effects are associated with Dopamine (D2) Receptor Antagonists?

A

Somnolence, nervousness, agitation, anxiety, dystonia, parkinsonism, Tardive dyskinesia (irreversible), Inc. prolactin release which causes impotence, menstrual changes, galactorrhea.

37
Q

What is the MOA for Tricyclic Antidepressants (TCA)?

A

Dec. reuptake of NE form the postganglionic sympathetic neuron which activates alpha2 receptor on presynaptic terminal and decreases ACh release from postganglionic parasympathetic neurons. Dec. ACh release causes decreased motility and decreased reuptake of DA and increased activation of D2R which decreases ACh release and decreases motility.

38
Q

What is the MOA for Atropine?

A

Direct antimuscarinic which causes decreased peristalsis.

39
Q

What is Atropine given with?

A

Included with diphenoxylate (opiate)

40
Q

What is the MOA for Macrolides?

A

Stimulate motilin receptors in smooth muscle which activates the MMC and increases peristalsis.

41
Q

What do you need to remember about giving Macrolides for increasing motility?

A

Subclinical doses are effective but increase antibiotic resistance.

GI Final (9 decks)

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