GI Pharma Flashcards
OTC antacids
(a) What are they?
(b) Absorbed?
(c) Onset?
(d) Possible side effect
(e) Example
OTC antacids (a) weak bases to neutralize stomach acid (b) Not absorbed (c) Rapid onset (d) possible side effect = constipation Ex: Tums, Rolaids
TUMS
OTC antacid (weak base) to neutralize stomach acid
Zantac
H2 receptor blocker- available OTC
Pepsid
H2 receptor- available OTC
PPIs- describe process of absorption and activation
PPIs ingested as a weak base. Taken up by activated parietal cells (activated by eating) and protonated.
Then protonated PPI can covalently bind and inactivate HK ATPase
2 limitations of PPIs
- doesn’t inhibit nighttime acid secretion (parietal cell inactive) => nocturnal acid breathrough
- Short half life => long time (3-5 days) until peak onset
Biggest worrisome risk of PPIs
-Infections: specifically C. dif and pneumonia
3 ways prostaglandins are protective against acid
- decrease acid secretion
- increase bicarb and mucous secretion
- increase musocal bloodflow
When do you take antacids?
30-60 minutes before meal (usually right before breakfast) b/c parietal cells get activated upon eating => most drug will be taken up and prootnated
Sucralfate
-treat ulcers
Adheres to ulcers and acts as barrier of diffusion of H+ ions and pepsin
Define nauseau
subjective, painless feeling that one may vomit
Stimulation of what area causes nausea and vomiting?
-4th ventricle of the brain = area postrema
What are some triggers of the area postrema?
- drugs: dopamine agonists
- toxins
- metabolic causes: uremia, hypercalcemia
- radiation exposure
List some antiemetics
Antiemetics = anti-nausea
- Dopamine antagonists
- Serotonin receptor antagonists
- Tricyclic anti-depressants
List drugs w/ some antiemetic properties
-antihistamines, anticholinergics
Osmotically active laxatives
- increase the water content of stool => bowel distention and increased peristalsis
- very quick onset: 1-3 hrs
ex: Miralax, Go lightly, MIlk of Magnesia, Epsom Salt
Miralax
Osmotically activate laxative
Bulk Laxatives
= Fiber laxatives: insoluble and non-absorbable
- increase stool volume to trigger stretch receptors => reflex peristalsis to move contents forward
- must be taken w/ lots of water
- safest, often first line
What do you need to be careful of when taking Metamucil?
Metamucil = bulk laxative
-make sure to take w/ lots of water
Irritant Laxatives
- causes irritation of the enteric mucosa/nerves => water secretion => soften stool and increased volume => increased peristalsis
- not first line, don’t want to irritate stuff if you don’t have to
Senakot
Irritant laxative
Lubiprostone/Amitiza
activates Cl- channels = new mechanism of laxative
-used in IBS-C pts
Lubricant laxatives
Retards water absorption to lubricate and soften stool
Stool Softener
Not effective as a laxative
-decreases surface tension of stool
Adsorbants
= Antidiarrheals
- coats the gut wall
- can bind to stuff (bugs, toxins, but also other drugs) to expedite their excretion
- can cause tongue to turn black
ex: pepto-bismol, kaopectate
Pepti-bismol
= Adsorbant = Antidiarrheal
Systemic anti-diarrheals
- opiate biased
- slows GI mobility/peristalsis to allow for increased water absorption
-also can use anticholinergics as systemic antidiarrheal
What is the most universal symptom of IBS?
Abdominal pain
2nd most common = altered bowel habits
Amitripyline
= TCA (tricyclic antidepressant)
- inhibitory effect on the gut
- used as antiemetic and to reduce sensitivity to pain in IBS
Serotonin receptor blockers in IBS
- 5 HT3 and 5 HT4 antagonists previously used to treat IBS but taken off the market b/c of side effects
- 5 HT3 antagonist => ischemic bowel (but a dif form used as antiemetic)
- 5 HT4 antagonist => cardiac events
What is Ogilvie’s syndrome?
= pseudoobstruction = mimics acute large bowel obstruction
-colon distends (most common in cecum) and risk of perforation is high => very high mortality if distends enough
=> if distends to a certain degree use Neostigmine (Ach-ase inhibitor) to cause decompression
What can be used to treat pruritis in cholestatic disease?
- bile acid sequestrant
- CHolestyramine = Questran
Medication for variceal bleeding
Somatostatin mimic = Octreotide = Sandostatin
-inhibits release of many GI hormones (ex: gastrin, CCK etc) => decreases secretion from intestine and pancreas and decreases GI motility
