Gi: Laxatives, Antidiarrheal, Antiemetics

Front 1

what is dumping?

Back 1

accelerated gastric emptying and or impaired gastric accommodation.

Front 2

what is gastroparesis?

Back 2

abnormal gastric motility, delayed in absence of obstruction.

Front 3

etiology of gastroparesis?

Back 3

DM, idiopathic, post surgical, drug induced, chronic intestinal pseudo obstruction

Front 4

what is the peristalic reflex?

Back 4

it is 5 HT serotonin and calictonin gene-related peptides involved.

for contraction: ach, tachykinins, substance P
for relaxation: NO, opiates (endogenous), VIP, GABA, somatostatin, 5HT

Front 5

wHat are the regulators and modifiers a part of the myentric plexus and ANS?

Back 5

parasympth - excitatory to nonsphincters
sympth - inhibitory to non sphincter, excitatory to sphincters

Front 6

what regulats secretion, fluid transport, and vascular flow?

Back 6

submucosal plexus

Front 7

what are the mediators for fluid secretion into the gut?

Back 7

5ht, VIP, toxins, increased cAMP, neuropeptide Y, NO,

Front 8

what is tx for constipation?

Back 8

focus on prevention, lifestyle changes (including fiber 20-25 gm.day), bowel training.
use safest drugs for shortest duration

Front 9

what is normal for GI?

Back 9

BM 3x/day - 3xweek

no straining and complete evacuation

Front 10

what assessments of GI for constipation?

Back 10

lifestyle
bowel habits
OLDCARTS
drugs
self tx
hx of colorectal problems

Front 11

what drugs are associated with constipation?

Back 11

analgesics
anticholinergics
antihistamines antidepressants
antipsychotics
cation containing agents
iron
aluminum
neurally active agents
opiates
antiHTN
ganglionic blockers
vinca alkaloids
ca channel blockers
5HT3 antagonists
anticonvulsants

Front 12

What are the four classes of laxatives?

Back 12

stimulant
osmotics
bulk
stool softener

Front 13

types of stimulants? how work?

Back 13

bisacodyl
senna
castor oil

increase parastalsis by stim nerves

Front 14

types of osmotics?MOA?

Back 14

na phosph
mg2+ sulfates
mg 2+ hydroxide
mg 2+ citrate

water pulled into intestine

Front 15

types of bulk laxatives? how work?

Back 15

psyllium
methylcellulose
polcarbophil

absorbs water, expands, and distends colon

Front 16

types of stool softeners? MOA?

Back 16

softens and lubricates
docusate salts
mineral oil

Front 17

MOa of bulk lax?

Back 17

insoluble, poorly fermented fibers

deitary fiber

hydrophillic colloids that absorb water, increase fecal bulk and increase perstalsis as activate defecation reflex, evacuates descending colon

methylcellulose and polycarbophil are more resistant to bacteria degradation

Front 18

How to take bulk laxatives?

Back 18

safe to use chronically, less habit forming

take with plenty of fluids, dont give if person cant sit upright since can cause esophageal and intestinal obstruction

not absorbed and little impact on nutrient absorption

onset is 12 hrs

Front 19

what drugs do bulk lax decrease absorption?

Back 19

may decrease absorption if warfarin, digoxin, tetracycline, salycilates

Front 20

MOA of osmotic lax?

Back 20

causes osmotically mediated water retention. ma salt make also stim release of CCK which increases secretion of water and elect and intestinal motility

also note that lactulose can be used to trap ammmonia in in gut and decreases its circulation this is a type of ma sulfate

onset is 30 min to 6 hours

Front 21

ADR of osmotic lax?

Back 21

diarrhea and N/v

Front 22

when are osmotic indicated and contraindicated?

Back 22

uses: bowel prep. removal of toxins

contra: pt with n/v of unknown origin, abd pain, impaction, and obstruction

use cautiously in thse with renal insuff and seizure meds

dont give within 1 hr of laxative therapy

Front 23

MOA of stool softeners?

Back 23

anionic surfactant that lowers surface tension of stool - incorporates water and lipids --- soften stools

docusate salts: onset s 24-72 hours, rectal 2-15 min

can lead to dpend and diarr if excessive

Front 24

ADR of stool softeners?

Back 24

cramps, diarrhea, dehydration, IBS like condition, rash, hypersensitivity

Front 25

MOA of stimulant laxatives?

Back 25

irritate bowel, causing low grade inflam, stim PG production --> increase cAMP ---> increase water and electrolyte accum in lumen, stim myenteric plexus/motlity

Front 26

when are stimlaxatives indicated?

Back 26

constipation from bed rest, drug induced, spinal cord and neuro dx, IBS

Front 27

Bisocodyl instruction?

Back 27

pro drug that is enteric coated, converted in colon by bacteria to ative form. DONT USE WITH DAIRY.

onset < 6 hrs, suppository 15-60min

Front 28

senna onset?

Back 28

stimulant that takes 1-3 days oral and 24 hours sup posit

Front 29

ADR of stimulants?

Back 29

cramping, diarrhea, dehydration, dependence, IBS

drug interactions: decreasse in transit time can alter drug absorption

Front 30

ADR of castor oil?

Back 30

stim laxative that when taken with disulfiram can increase risk of disulfram like reaction

Front 31

other tx for constipation?

Back 31

glycerin enema or suppository
lubiprostone - PG derivative (cl channel activator, fluid flows and increases fluid secretion into gut, few side effects)

mineral oil -- can be absorbed and decrease absorption of fat soluble vitamins

enema - bowel distention resulting in evacuation reflex. if hypotonic can cause hyponatremia. na phosphate can cause hypocalcemia

Front 32

what laxatives guidance for preg, elderly, and children?

Back 32

preg - lifestyle changes first
best use bulk forming since not systemically absorbed
ducosate - stool softener next acceptable

elderly - lifestyle, then bulk forming, then osmotic laxatives, not stimulants

children - polythelene glycol most effective

Front 33

MOA of prokinetics for gastroparesis?

Back 33

stim of myenteric plexus. ach primary transmitter, but clinically used prokinetics usually target upstream targets that enhance release of act. interferes with normal coordination of motility.

Front 34

what are examples of prokinetics used for gastroparesis?

Back 34

cholinergics (muscarinic agonist): bethanecol
neostagmine (cholinesterase inhibitor) - off label
dopamine receptor antagonist
5 HT receptor modulators
motilin agonists

Front 35

What dopamine receptor antagonist is used for gastroparesis? MOA?

Back 35

inhibits intestin motility by supp of Ach release through presynaptic D2 receptors

metaclopramide - stim upper GI contraction and increases lower esophageal tone

binds to 5 HT4 and central 5 HT3

Front 36

directions for metoclopramide?

Back 36

Take 30 min premeal and at bedtime orally
􀁻 Well absorbed
􀁻 Conjugated in liver
􀁻 Renal excretion – t1/2 = 4-6 hr
􀁻 Crosses BBB and placental membranes

available IM and IV

Front 37

ADR for metoclopramide?

Back 37

ADR – Pregnancy category B, not recc
􀁻 Parkinson-like syndrome – with chronic use – tartive
diskinesia which may be irreversible
􀁻 Sedation and diarrhea

Front 38

MOA of 5ht receptor modulators?

Back 38

􀁻 90 % of serotonin in GI tract
􀁻 5-HT triggers peristalsis
􀂄 Though some receptor subtypes are inhibitory
􀂄 Also stimulates nitric oxide and Ach release
􀁻 Tegaserod (Zelnorm) – 5-HT4 partial agonist
􀂄 Only drug approved for constiipation

Front 39

MOa motilin agonists?

Back 39

Motilin is 22 aminoacid peptide – found in M cells and
enterochromaffin cells of gut
􀁻 Contracts upper GI muscles
􀁻 Action mimicked by
􀁻 Erythromycin, azithromycin, clarithromycin
􀁻 Limited use due to side efects