Anti-constipation Flashcards

1
Q

What are the drug classes for anti-constipation?

A

BOSSCO-5: Bulk-forming, osmotics, softener, stimulant, Cl channel activator, Opioid antagonist, 5-HT4 receptor agonist

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2
Q

Bulk-forming agents

A

Plant: psyllium, methylcellulose; synthetic: polycarbophil

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3
Q

MoA of bulk-forming agents

A

Hydrophillic colloid that absorbs water into lumen –> forms bulk/increase stool mass

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4
Q

SE of bulk-forming agents

A

Digestion of plant fibres leads to gas production and results in flatus, distension
Interferes with absorption of other drugs

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5
Q

Surfactant/softener

A

Docusate, mineral oil

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6
Q

MoA of surfactant

A

Decrease surface tension and increases H2O penetration into stools and make them softer
Also, mineral oil lubricates and prevents excessive H2O absorption from stool

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7
Q

SE of surfactants

A

Mineral oil: unpleasant taste, lipid pneumonitis with aspiration, impaired absorption of fat-soluble vitamins ADEK

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8
Q

Osmotic laxatives

A

Nonabsorbable sugars/salts (lactulose, sodium phosphate), balanced polyethylene glycol (PEG)

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9
Q

MoA of osmotics

A

Osmotically-mediated water movement into bowel to increase stool liquidity & volume

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10
Q

How fast do osmotic laxatives take to work

A

Highly effective — 1-3h

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11
Q

SE of Osmotics

A

Lactulose can cause flatus, abdominal cramps when digested by gut bacteria
Sodium phosphate can cause electrolyte abnormalities (hyperPO4,Na//hypoCa,K) that could cause arrhythmias, acute renal failure
Balanced PEG avoids electrolyte shifts, does not cause flatus

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12
Q

Precautions of osmotics

A

Due to electrolyte abnormalities caused by sodium phosphate, avoid in Px who have CVD, renal impairment, elderly

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13
Q

Stimulants

A

Anthraquinone derivatives: aloe

Diphenyl der.: Bisacodyl**

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14
Q

MoA of stimulant

A

Produce migrating colonic contraction by ENS stimulation, fluid secretion

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15
Q

What is bisacodyl usually combined with?

A

Bisacodyl + balanced PEG for colonic prep

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16
Q

SE of stimulants

A

Anthraquinone can cause brown discolouration of colon

Bisacodyl is safe for use

17
Q

Cl channel activator

A

Lubiprostone

18
Q

MoA of ClCA

A

Stimulates type 2 Cl- channels and increase Cl-rich secretion –> stimulates motility, decrease transit time

19
Q

Contraindication of ClCA

A

Contraindicated in pregnancy

20
Q

SE of ClCA

A

Return of constipation after discontinuation, delayed gastric emptying

21
Q

Opioid antagonists

A

Methylnaltrexone (for opioid-induced constipation), alvimopan (post-op ileus)

22
Q

MoA of opioid antagonist

A

Blocks intestinal MOR –> ensures normal GI motility

Additionally, these don’t cross BBB –> analgesic effect of opioids not affected

23
Q

SE of opioid antagonist

A

Risk of CV toxicity with alvimopan use — only use short-term

24
Q

5-HT4 agonist

A

Prucalopride, cisapride

25
Q

MoA of 5-HT4 agonist

A

Stimulate 5-HT4 receptor on submucosal intrinsic primary afferent neurons (IPAN) terminals –> enhance release of NT —> stimulate enteric neurons to promote peristaltic reflex & colonic mass movement

26
Q

SE of 5-HT4 agonist

A

Prucalopride: high affinity agonist — low risk of significant CVS effect
Cisapride: partial agonist —risk of adverse CV events