Nausea Vomiting Constipation Diarrhea IBS Pharmacology

Nausea/Vomiting Tx

1st line:
antacids/H2RA
serotonin antagonists
phenothiazines
banzamides
butyrophenones

2nd line:
cannabinoids
benzodiazepine
corticosteroids
antihistamines
anticholinergics
aprepitant

drugs/ketoacidosis/uremia→phenothiazines+metoclopramide

obstruction/gastroparesis/visceral pain→metoclopramide/analgesics

motion sickness/vestibular inflammation→antihistamine/anticholinergics

higher brainstem (emotions/sights/smells/tastes)→benzodiazepenes/dronabidol/corticosteroids

Anticholinergics

MX: scopolamine

MOA: blocks muscarinic receptors in vestibular system

I: motion sickness
post-op nausea/vomiting

ROA: patch
perioperative: 1 behind ear before surgery→remove 24 hours after surgery

motion sickness: 1 patch behind ear 4 hours prior to exposure+every 3 days PRN (best: 12 hrs before)

AE: anorexia
blurry vision
constipation/confusion
dry mouth
sedation/stasis of urine

CI: narrow-angle glaucoma
BPH
not immediate relief

Antihistamines

MX: dimenhydrinate
diphenhydramine
meclizine

MOA: blocks histamine receptors

I: nausea
vomiting
motion sickness

AE: drowsiness
blurred vision
constipation
dry mouth

CI: nursing mothers
newborns/premature infants
elderly
narrow-angle glaucoma
BPH
with other sedating drugs

Dopamine Antagonists

MX: prochlorperazine
promethazine

MOA: blocks dopamine receptors in chemoreceptor trigger zone (CTZ)
anticholinergic
alpha-adrenergic antagonist

ROA:
PC: PO/IV/IM Q3-4h
PR BID

PM: PO/IV/IKM/PR Q4-6h

I: nausea
vomiting

AE: sedation
orthostatic hypotension
extrapyramidal symptoms (dystonia/tardive dyskinesia/akathisia)

black box: injectable promethazine→extravasations

CI: under 2y/o
comatose
large amounts of CNS depressants

Dystonia

within 2-5 days of starting meds

involuntary/repettive muscle contractions

abnormal posturing

Tardive Dyskinesia

uncontrollable/abnormal repetitive movements

Dopamine Antagonists

MX: metoclopramide

MOA: blocks dopamine receptors in chemoreceptor trigger zone (CTZ) and GI tract
increases lower esophageal sphincter tone
increases gastric motility

I: PONV
delayed CINV
diabetic gastroparesis

ROA:
POV: IV Q4-6h
CINV: IV 30 min before chemo repeated Q2h with 2 doses→Q3h with 3 doses
lower EPS sx→diphenhydramine pretreatment

AE: somnolence
reduced mental acuity
hyperprolactinemia
hyperprolactinemia
gynecomastia
etc.

Black box: tardive dyskinesia

CI: epilepsy history
seizure history
GI hemorrhage
GI obstruction
pheochromocytoma

Dopamine Agonists

MX: haloperidol

MOA: blocks dopamine stimulation in chemical trigger zone

I: prevent PONV
palliative care

CI: hypotension
QT prolongation

Corticosteroids

MX: dexamethasome
methylprednisolone

MOA: antiemetic

I: prevent+treating CINV
radiation induced NV
PONV
adjunctive txt

AE: GI upset
anxiety
insomnia
hyperglycemia

long term: picture

Selective Serotonin (5HT3) Antagonists

MX: ondansetron
granisetron
dolastron
palonosetron

MOA: block 5HT3 receptors in CTZ and visceral nerve fibers

I: NVP
PONV
CINV

ROA: picture

AE: headache
solemnence
diarrhea
constipation
prolonged QT interval

Neurokinin-1 Receptor Antagonist (NK-1)

MX: Aprepitant
forsaprepitant
rolapitant

MOA: blocks NK-1 receptors in chemoreceptor trigger zone and GI tract

I: prevent CINV
PONV

ROA:

Products	Dose
Aprepitant (Emend)	CINV: PO 125 mg on day 1, 1 hour prior to chemotherapy, 80 mg on days 2 and 3 PONV: PO 40 mg within 3 hours prior to induction
Fosaprepitant (Emend IV)	Single dose: IV 150 mg, 30 minutes prior to chemo on day 1, oral administered on days 2 and 3
Rolapitant (Varubi)	180 mg PO every 2 weeks

CINV: msut be given 5HT3 antagonists+dexamethasone

AE: fatigue
nausea
constipation
weakness
hiccups

CI: CYP3A4
CYP2C9
severe hepatic impairment

Pyroxidine (Vitamin B6)

MOA: anti-emetic
anti nausea

ROA: PO Q8h

I: pregnancy-induced nausea+vomiting

AE: headache

Constipation Tx

NP: dietary modification
increase exercise
discontinue offending agents
water enema

MX:
acute:
episodic constipation→osmotic laxatives
uncomfortable: glycerin suppositories
stimulant/saline laxatives

chronic:
1st line: bulk-forming agents
2nd line: osmotic/stimulant laxatives

Constipation Non-Pharmalogical Tx

dietary: fiber 20-25g/day
decrease processed foods
6-8 glasses of water/day

Exercise: walking
aerobic exercise

water enema: 200mL (adults)
around 30 min

Constipation Pharmalogical Tx

bulk formin: psyllium
methylcellulose
wheat dextrin

osmotic: lactulose
sorbitol
magnesium citrate
magnesium hydroxide
sodium phosphate
glycerin supplements
polyethylene glycol

Stimulants: bisacodyl
senna
castor oil

lubricants: mineral oil

emollients: docusate

Bulk-Forming Laxatives

MX: psyllium
methylcellulose
wheat dextrin

MOA: swelling in intestinal fluid
forms gel to aid in elimination and peristalsis

I: 1st line for constipation after prevention/fiber supplements

ROA: relief in 1-3 days
P: PO TID

M: PO TID
2 caplets 6x daily

W: PO TID

AE: flatulence
abdominal cramping
take with water

CI: fecal impaction
intestinal obstruction

Osmotic Laxatives (Lactulose+Sorbitol)

MX: lactulose
sorbitol

MOA: water enters lumen→increases peristalsis

I: acute+chronic constipation

ROA: relief in 1-3 days
L: PO daily
S: PO one dose
enema (25-30% solution)

Osmotic Laxatives (Magnesium+Sodium)

MX: Magnesium citrate
magnesium hydroxide
Sodium phosphate

MOA: water+electrolytes enter lumen of colon

I: acute bowel evacuation

ROA: relief in 1-6 hours
MC: PO single/divided dose
MH: PO QHS/divided dose
S: PO x 30 min before a meal/empty stomach

AE: dehydration
electrolyte disturbances
flatulence
abdominal cramping
with water

CI: ascites
renal impairment-sodium phosphate
edema
megacolon
GI obstruction

Osmotic Laxatives (Glycerin Suppositories)

MX: glycerin

MOA: water enters lumen of colon→stimulates rectal contractions

I: acute constipation
fecal impaction
peds safe

ROA: PR daily

AE: cramping
rectal irritation

Osmotic Laxatives (Polyethlylene Glycol)

MX: polyethylene glycol

MOA: water enters lumen of colon

I: acute+chronci constipation
prevenetion

ROA: relief in 2-3 days
4-8oz liquids daily

AE: upset stomach
bloating
cramping
gas
electrolyte balance

Stimulant Laxatives (Bisacodyl+Senna)

MX: Bisacodyl
Senna

MOA: nerve plexus of smooth muscle of intestine
alters fluid+electrolyte secretion

I: constipation
intermittent use

ROA:
B: PO Qhs
PR once daily

AE: cramping
diarrhea
nausea
vomiting
electrolyte imbalance
don’t use more than 10 days

CI: intestinal obstruction
GI inflammation
abdominal pain