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Gastrointestinal - Pharmacology > Laxatives > Flashcards

Laxatives Flashcards

1
Q

What are the 5 types of laxatives?

A
  1. Dietary fiber and Bulk-forming laxatives.​
  2. Surfactant laxatives​
  3. Osmotic laxatives​
  4. Stimulant laxatives.​
  5. Miscellaneous laxatives.​
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2
Q

What are the 3 types of Dietary fiber and Bulk-forming Laxatives?
• what products fall into these categories?

A

Psyllium husk​
• Effer-syllium and Metamucil
​

Semisynthetic celluloses​
(carboxymethyl-cellulose, ​
methylcellulose)​
•Citrucel and Cologel 
​

Polycarbophils​
• Mitrolan

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3
Q

What are the 3 types of Surfactant Laxatives?

• What products fall into these categories?

A

Docusates (Dioctyl sodium (Ca2+) sulfo-succinate)
•Colace and Surfak

Poloxamers
• Polaxamer 188

Castor Oil
• Neolid and Purge

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4
Q

What are the 2 types of Stimulant Laxatives?

• what products fall into these categories?

A

Diphenylmethanes
• Modane and Ducolax

Anthraquinones
•Senokot

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5
Q

What are the 3 categories of Saline and Osmotic Laxatives?

• what products fall into these categories?

A

Magnesium containing Laxatives
• Magnesium sulfate (epsom salts), Magnesium hydroxide (milk of magnesia), Magnesium Citrate (citroma)

Phosphate containing Laxatives
•Sodium Phosphate tablets (Visocol, OsmoPrep)

Non-digestable Sugars and Alcohols
•Lactulose

Glycerine

Polyethylene Glycol electrolyte soln

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6
Q

What laxatives are used in the treatment of IBS-C?

A

Lubiprostone

Linaclotide

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7
Q

What are the 3 general Categories or Anti-diarrheal agents?

A
  1. Ones that absorb water
  2. Absorbers of Etiologic Factors in lumen
  3. Those that Decrease Motility
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8
Q

What two general classes or drugs are used to decrease GI motility?

A
  1. Opiates

2. Anticholinergics

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9
Q

Methyl Cellulose/Psyllium
• MOA
• Adverse Effects

A

MOA
• Psyllium Husk - HydroPHILIC mucoloid that forms a collagenous mass when mixed with water
• Methyl Cellulose - HyodroPHILIC mucoloid that is DIGESTABLE and forms a COLLOID mass when mixed with water

Increase delivery of water to ​
the colon => Increase bulk. => Reduce pressure in sigmoid ​Colon​

Net result: more formed stools.​

Adverse Effects
• Psyllium - Allergic reactions, flatulence, borborygmi, intestinal obstruction; May inhibit coumarin absorption

•Methyl Cellulose - may inhibit the absorption of drugs.​

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10
Q

Magnesium Sulfate
• MOA
• Adverse Effects

A

MOA

  1. Produce laxation by their osmotic effect
  2. They also increase CCK. CCK increases intestinal motility and secretion.

Adverse Effects
• None mentioned

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11
Q

Magnesium Citrate
• MOA
•Adverse Effects

A

MOA

  1. Produce laxation by their osmotic effect
  2. They also increase CCK. CCK increases intestinal motility and secretion.

Adverse Effects
• Can have Cathartic effect at higher doses leading to evacuation of the GI tract

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12
Q

Buffered Phosphate
• MOA
• Adverse Effects

A

MOA
•exert an osmotic effect which retains water in the lumen of the G. I. tract
• Can be given before colonoscopy to completely evacuate the GI tract

Adverse Effects
• None mentioned

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13
Q

Bisacodyl
• MOA
•Adverse Effects

A

MOA

Adverse Effects

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14
Q

Senna
• MOA
•Adverse Effects

A

MOA
• Acts in COLON predominantly to increase mucosal permeability and allow more diffusion of water and electrolytes into the lumen.
•Increases intestinal contractility by STIMULATING the MYENTERIC PLEXUS
•Stimulates PROSTAGLANDIN synthesis to increase intestinal secretions

*These are more gentle than synthetic drugs like diphenylmethanes

Adverse Effects
May cause melanotic (dark) pigmentation of the colonic mucosa, abnormal urine coloration​

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15
Q

Casara sagrade extract
• MOA
•Adverse Effects

A

MOA
• Acts in COLON predominantly to increase mucosal permeability and allow more diffusion of water and electrolytes into the lumen.
•Increases intestinal contractility by STIMULATING the MYENTERIC PLEXUS
•Stimulates PROSTAGLANDIN synthesis to increase intestinal secretions

*These are more gentle than synthetic drugs like diphenylmethanes

Adverse Effects
May cause melanotic (dark) pigmentation of the colonic mucosa, abnormal urine coloration​

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16
Q

Castor oil
• MOA
•Adverse Effects

A

MOA
Rapid-acting and effective anionic surfactant that produces catharsis i.e. complete evacuation of the bowels => stimulates intestinal peristalsis​***(compare to docusate sodium - another surfactant laxative)

Adverse Effects
Colic, dehydration, and electrolyte imbalance with overdose; Can induce uterine contraction in pregnant women.​

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17
Q

Doscusate Sodium
• MOA
•Adverse Effects

A

MOA
Anionic surfactant. Primarily used as a stool softener ​
*Reduce the strain of defecation. ​
*Has no effect on intestinal peristalsis.​

Adverse Effects

  • Not for use during abdominal pain or vomiting; ​
  • Can irritate the intestinal mucosa and increase absorption of other drugs. ​
  • Recommended for short-term use.​
18
Q

Mineral oil

• MOA

A

MOA

Mixture of Hydrocarbons that Penetrate and Soften the stool

19
Q

Glycerine

• MOA

A

MOA

osmotic AND lubricant effects, suppository.

20
Q

Diphenoxylate and Atropine

• MOA

A

MOA
• Diphenoxylate - has opiate-like effects of decreasing motility, spasm, and increasing sphincter tone

• Atropine - also blocks cholinergic stimulation of the GI tract further reducing motility

21
Q

Loperamine
• MOA
•Adverse Effects

A

MOA

Interacts with intestinal opioid receptors and binds to AND inhibits the calcium-binding protein calmodulin.​

22
Q

Paregonic
• MOA
• what’s in it?

A

MOA
• Opiate - decreased motility, spasms, and increased sphincter tone

contains 0.04% morphine in benzoic acid, camphor, anise oil tincture. ​

23
Q

Lubiorostone

• MOA

A

MOA
• Activates Chloride Channels in a cAMP dependent fashion
• Increases BOTH secretion AND motility

24
Q

Linaclotide

• MOA

A

MOA

• Works on Guanylyl Cyclase 2 to INDIRECTLY activate chloride channels in the intestine

25
Q

Rifaximin
• MOA
•Adverse Effects

A

MOA
Locally acting antibiotic that is not absorbed systemically. It has broad spectrum of activity that target various strain of E. Coli bacteria.​
​
Adverse Effects
PERIPHERAL EDEMA (swelling, usually in ankles or lower limbs), nausea , dizziness, fatigue, and ABDOMINAL ASCITES.​

26
Q

Eluxadoline

• MOA

A

MOA
• mixed opioid receptor regulator
•targets opiate receptors in the GI tract, with MINIMAL CENTRAL EFFECTS
•AGONIST mainly on µ- and k-opioid receptors; ANTAGONIST on delta-opioid-R (C-IV ). ​
• decreases GI motility and reduces the sensitivity of myenteric plexi.​

27
Q

Polycarbophils
• MOA
• Adverse Effects

A

MOA
Hydrophilic polyacrylic resins; absorb 60-100x their weight in water.​

Increase delivery of water to ​
the colon => Increase bulk. => Reduce pressure in sigmoid ​Colon​

Net result: more formed stools.​

Adverse Effects
​Ca+ polycarbophils release Ca+ that is contraindicated with tetracycline usage.​

28
Q

What is the overall purpose of surfactant laxatives?

• what patients would these be most beneficial to?

A

Surfactant Laxatives:
• Decrease the strain of defecation

• This is useful in patients with CHF etc. who don’t need to be staining

29
Q

Why can’t surfactant laxatives be used for long periods of time?

A

Do not use these for a long period of time b/c they damage the mucosa and cause increased mucous production

30
Q

Diphenylmethans
• MOA
• Adverse Effects

A

MOA
• Acts in COLON predominantly to increase mucosal permeability and allow more diffusion of water and electrolytes into the lumen.
•Increases intestinal contractility by STIMULATING the MYENTERIC PLEXUS
•Stimulates PROSTAGLANDIN synthesis to increase intestinal secretions

Adverse Effects
Overdosing can cause excessive fluid and electrolyte loss, intestinal enterocyte damage leading to colonic inflammatory response.

31
Q

Lactulose

• MOA

A

MOA
•a semisynthetic disaccharide which is not absorbed and produces an osmotic laxative effect.​
•is metabolized by enteric bacteria to organic acids such as lactic, formic and acetic acid. ​
• These acids can convert NH3 in the feces to NH4+ so that it is excreted instead of absorbed

This drug can be useful in someone with hepatic encephalopathy

32
Q

Polyethylene Glycol Solution
• MOA
• Use

A

MOA:
• Osmotic and Lubricant Effects

Use:
for colonoscopy, where complete evacuation is needed.

33
Q

What is the MOA of the laxatives given in IBS?

A

Chloride channel regulators are used in the management of IBS-C

34
Q

What are the side effects of laxative abuse?

• what should you tell these patients to do?

A

-overuse of laxative leads to thorough constipation that requires several days to accumulate bulk.​
​
-Lag in defecation is interpreted as continued constipation.​
​
-Take more laxatives-vicious cycle.​
​
-If continued, bowel becomes unresponsive.​
​

***Tell these patients to discontinue all laxatives and tell them to eat or supplement FIBER to bulk up stools

35
Q

What antidiarrheal agents work by soaking up water?

A

Cellulose derivatives and semisynthetic polysaccharides

36
Q

What antidiarrheal agents work by absorbing the etiologic factors causing the diarrhea in the lumen?

A

BISMUTH and CHARCOAL are agents that adsorb harmful bacteria, viruses or toxin. ​
​
*Bismuth subsalicylate is effective in prevention of Traveler’s diarrhea and in treatment of Helicobacter pylori infections.​

37
Q

How do opiates work to change gastric motility?

• What is the summative result of all of these effects?

A

Mechanism of action:​
Opiates DECREASE salivary, gastric and intestinal SECRETIONS
​
Opiates DECREASE the MOTILITY of the stomach and intestines.​
​
Opiates INCREASE MUSCLE TONE.​
​
Opiates INCREASE the SPHINCTER TONE including the tone of the external anal sphincter “reduce urgency”.​
​
Opiates are ANTI-SPASMOTICS and DECREASE CRAMPS ​
​The sum of these effects is that opiates increase the contact time between ingested matter and the reabsorbtive intestinal epithelium​

38
Q

Dicyclomine
• MOA
• Use?

A

MOA:
• Anticholinergic that works to block vagal stimulation and alleviate CRAMPS
• NOTE that unlike atropine this does NOT cross the BBB
so will have LESS CNS effects

39
Q

What drugs are often combined with Anticholinergics in the tx of diarrhea?
• why?

A

Benzodiazepines are often combined with anticholinergics because of anxiety that may be associated with fecal retention from the anti-cholinergic medication

40
Q

Rifaximin
• Clinical Uses
• Contraindications

A

Clinical Uses:
• Hepatic Encephalopathy
• Traveler’s Diarrhea
•IBD-D

Contraindications:
• in patients with allergy to rifaximin and avoid its use in pregnancy.​

41
Q

Eluxadoline

• Contraindications and Side Effects

A

DO NOT USE THIS MED FOR MORE THAN 2 wks

  • Activation of µ-opioid receptors => gall bladder constriction + increased risk of sphincter of Oddi spasm => resulting in abdominal pain, PANCREATITIS, HIGH LFTs
  • Patients without a gallbladder, need to be monitored for abdominal pain or pancreatitis.​
  • Alcoholics or patients who drink more than 3 alcoholic beverages per day => increased risk for acute pancreatitis.​
  • PREGNANT patients. ​

Gastrointestinal - Pharmacology (2 decks)

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