Pharmacology

Question 0

Prokinetic drug - metoclopramide ( Apo- Metoclop , clopra)

Answer 0

D2 ( dopamine ) and 5-HT3 ( hydroxytryptamine) receptor antagonist.

Question 1

Prokinetic drugs

Answer 1

They promote upper git motility . Diseases that damage nerves to the viscera ( diabetis) result in loss of motility in the esophagus and stomach. This results in delayed GI emptying , nausea , and severe bloating .

Question 2

MOA of metoclopramide

Answer 2

Blocks D2 and 5HT3 receptors located on GI smooth muscle , which results in an acceleration of GI emptying and intestinal transit time ( prokinetic activity)

Question 3

Metoclopramide

Answer 3

Affects dopaminergic neurons in the basal ganglia and substantia nigra producing parkinson disease as side effect

Question 4

What are bulk forming laxatives

Answer 4

Undigestible plant , fruit , or veg products ( ie; high fibre content )

MOA : form gels within the GI lumen which results in H2O retention , distention , and increased peristaltic activity .

Clinical use :
Constipation

Side effects;
Flatulence n reduced drug absorption ( cardiac glycosides)

Question 5

What are saline laxatives

Answer 5

Magnesium hydroxide (milk of magnesium) ; magnesium citrate

Hypertonic solutions of poorly absorbable salts(mg , citrate, sulfate , phosphate)

MOA: cause H2O accumulation within GI lumen which results in distention and increased peristaltic activity

Clinical use:
Constipation
Colonic lavage prior to surgery , radiology , colonoscopy , elimination of parasites

Side effects :
Dehydration and electrolyte imbalance
Contraindicated in pts with congestive heart failure or impaired renal function

Question 6

What are osmotic laxatives

Answer 6

Sorbitol , lactulose , polyethylene glycol , glycerine

Hyperosmotic agents

Question 7

Sorbitol and lactulose

Answer 7

Nonabsorbable sugars. Cause H2O accumulation with in the GI lumen which results in distention and increased peristaltic activity.

Clinical use :
Constipation and chronic hepatic encephalopathy ( reduces ammonia absorption)

Side effects;
Flatulence , abdominal cramps , nausea

Question 8

Polyethylene glycol

Answer 8

Nonabsorbable polymer in an isotonic solution which increases osmolarity within GI lumen.

Clinical use :
Colonic lavage prior to colonoscopy ( pat must drink 3-4L of the solution)

Side effects:
Diarrhea

Question 9

Glycerol

Answer 9

Clear , colorless , syrupy liquid ( C3H8O3)

Use: constipation

Question 10

What are stimulant laxatives ?

Answer 10

Phenolphthalein , Bisacodyl , Senna , Casara sagrada

Question 11

MOA of stimulus laxatives I

Answer 11

Cause h2O accumulation with in the GI lumen ( by inhibiting Na+ k+ Atpase ) and increased peristaltic activity ( by stimulating Auerbach plexus )

Clinical uses:
Constipation
Colonic lavage prior to surgery , radiology , colonoscopy

Side effects :
Fluid n electrolyte def
Abdominal cramps
Pink colored. Urine

Question 12

Emollient laxatives

Answer 12

Docusate sodium
Poloxamers

These are docusate salts that act as anionic surfactants.

Question 13

Castor oil

Answer 13

Distasteful oil that is metabolized to glycerol and ricinoleate ( an anionic surfactant and active agent)

MOA:
Ricinoleate decreases h2O and electrolyte absorption and increases peristalsis in the small intestine causing rapid evacuation.

Clinical use:
Severe constipation and colonic lavage prior to radiology. Castor oil is too powerful of a laxative to treat common constipation.

Side effects:
Dehydration
Contraindicated in pregnant woman

Question 14

Anti diarrheal drugs

Answer 14

Loperamide ( Imodium , Imodium - AD) 
Diphenoxylate HCL ( Lomotil , Motofen)

Question 15

Loperamide

Answer 15

Opioid receptor antagonist
Meperidine analog

MOA :
Stimulates opioid receptors in the enteric nervous system which results in decresed peristaltic activity

Side effects :
Abdominal cramps