GI Pharm 1 Flashcards
(27 cards)
Antiemetics
- Classes of drugs
- neurotransmitter receptor sites involved in the vomiting reflex
Classes
- Anticholinergics
- Antihistamines
- Dopamine Receptor Antagosists
- -Phenothiasines
- -Benzamides
- Serotonin antagonists
NT sites
- M1: muscarnic
- D2: Dopamine
- H1: Histamine
- 5-hydroxytryptamine (HT)-3
- -serotonin
- Neurokinin 1 (NK1) receptor
- -Substance P
Anticholinergic Agents
- receptor
- main drug in this category
- route of admin
- SE
Receptor
-M1 - mucarinic
Main Drug
-Scopolamine (used as prophylaxis agaist motion sickness
Route
-transdermally
SE
-dry mouth, drowsiness, vision distrubance
Antihistamines
- receptor
- drugs
- primary use
- SE
Receptor
-H1 blockers
Drugs
- diphenhydramine (Benadryl)
- Cylisine (cyclivert)
- Dimenhydrainate (Dramamine)
- Meclizine (dramamine less drowsy)
Primary use
-motion sickness
SE
- sedation
- anticholinergic SE
Dopamine Receptor Antagonists
-3 subclasses and their drugs
Phenothiazines*
- Prochlorperazine (Compazine)
- Promethazine (Phenergan) (could also be classified as an antihistamine)
- first line agents
Butyrophenones
-Antipsychotics
Bensamides*
- Metachlopramide (Reglan)
- Trimethyobenzamide (Tigan)
Phenothiazines
- drugs
- routes of admin
- work on which receptors
- SE
Drugs
- Prochlorperazine (Compazine)
- Promethazine (Phenergan)
Routes
-oral, rectal, IV
Receptors
-have antagonistic properties at D2, H1, and M1 sites
SE
- extrapyramidal rxn (dystonia)*
- tardive diskinesia*
- hypotension*
- sedation, drowsiness, anticholinergic effects
- use with caution in elderly, with other CNS depressants, poorly controlled sz, severe liver dz
*Acute dystonia can be treated with diphenhydramine 25-50mg IV or IM
Bensamides*
Metachlopramide (Reglan)
- receptors
- MOA
Trimethyobenzamide (Tigan)
-MOA
Metachlopramide (Reglan)
Receptors
- central and peripheral dopamine D2 antagonism at low doses
- weak 5-HT3 blockade at higher doses
MOA
-stimulates cholinergic receptors on gastric smooth muscle cells and enhances acetylcholine release at the NMJ
Trimethyobenzamide (Tigan)
MOA
- Unclear, works CENTRALLY in the area of the medulla oblongata
- considered the most potent antiemetic that does not have effects on the serotonergic, dopaminergic, or histamine systems, so it has a lower likelihood of causing undesired SE
Serotonin 5-HT3 Antagonists
- receptors
- clinical use
- SE
- Drugs
Receptors
-5-HT3-receptor blockade
Clinical Use
- great for postoperative and chemotherapy induced nausea and vomiting
- not great for nausea secondary to vestribular system etilogy (vertigo)
SE
- HA, dizziness, constipation
- generally well tolerated
Drugs
- Ondansetron (Zofran)***
- Granisetron (Kytril)
- Dolasetron (Anzement)
- Palonosetron (Aloxi)
Zofran (odansetron)
- Approved for use in adults?
- Approved for use in children?
- Pregnancy category?
- Drug Interactions
- routes of admin
- Approved for use in children and adults
- Pregnancy Cat B
Drug Interactons
-caution for serotonin syndrome, QT prolongation, Monitor liver function tests if prolonged use
Routes
-Solution (IV) or tablets (PO)
*Zofran is typically for short term use. Its somewhat expensive
Antiemetic drug selection should be based on the underlying disorder. N/V associated with chemotherapy is treated differently, what is a helpful adjunct?
Dexamthasone is helpful in treating Chemo n/v
Abx for tx of Infectious Diarrhea
Empiric Abx Therapy
first line: Ciprofloxacin (oral FQ)
Second line: oral macrolide (Azithromycin)
What are the rules for pharmacologic therapy for the symptomatic treatment of diarrhea?
If there is NO fever AND NO blood in stool, then you can use an anti-motility agent to decrease the number of stools per day
Anti-diarrheal: Bismuth subsalicylate
- aka
- MOA
- SE
- Caution
- CI
- use
AKA
-Pepto-Bismol
MOA
- considered an absorbent
- stimulates absorption of fluid and electrolytes across the intestinal wall but also when hydrolyzed to salicyclic acid, inhibits synthesis of a prostaglandin responsible for intestinal inflammation and hypermotility
SE
-dark stools, black tongue
Caution
- do not take with other ASA compnents
- can potentiate anticoagulants
CI
- ASA allergy
- infants and children
Use
-good for travelers diarrhea
Anti-diarrheal: Loperamide (Imodium)
- MOA
- preg cat
- duration of use
- SE
MOA
- acts directly on circular and longitudinal intestinal muscles, through opiois receptor
- -inhibits peristalsis and prolongs transit time
- -reduces fecal volume, increases viscosity
- -diminishes fluid and electrolyte loss
- -demonstrates antosecretory activity
- -Increases tone on the anal sphincter
Preg Cat C
Don’t use loner than a few days, need to reevaluate pt
SE
-abd pain/distention, constipation, dry mouth, nausea, dizziness, drowsiness
*Avoid if enteroinvasive organism is suspected
Anti-diarrheal: Dipenoxylate/atropine (Lomotil)
- MOA
- Preg Cat
- prescription or OTC
- SE
MOA
- Opiod antagonist and anticholinergic
- -inhibt peristalsis and slows intestinal motility
- -inhibits GI propulsion
- -Prolongs the movement of fluid and electrolytes through the bowel
Preg Cat C
Prescription
SE
- Paralytic ileus, toxic megacolon
- drowsiness, dizziness
- euphoria
- tachycardia
- pruitis, urticaria
- resp depression
- anticholinergic effects
*Avoid if enteroinvasive organism is suspected
Cholestyramine (Questran)
- Preg Cat
- MOA
- Useful when
- directions
Preg Cat C
MOA
-bile acid-binding agent used for hyperlipisemia
Useful
-for the tx of chronic diarrhea post cholecystectomy
Directions
-1 scoop mixed with fluid or foods BID
SE
- constipation
- abd apin/bloating
- vomiting
- excessive flatulence, diaarrhea
- weight loss
- decreased absorption of warfrin, thyroid hormones, digoxin, and thiazide diuretic
Laxitives
- types
- first line agents
- second line agents
- third line agents
Bulk forming
lubricants and surfactants
saline agents
hyperosmotic agents
stimulants
First line: Bulk forming (Metamucil), Ducosate derivatives (Colace), Glycerin
Second line: saline or hyperosmotic laxatives
Third line: Stimulant laxatives
Bulk forming laxatives
- OTC drugs
- MOA
- onset of action
- SE
- CI
- special considerations for
- -celiac pts
- -DM pts
- -pts on abx
OTC drugs
- Metamucil (psyllium)
- -preferred agent as it is the most physiologic
- Fibercon (Polycarbophil)
- Citrucel (methycellulose)
- Benefiber (wheat dextran)
- -not for pts with celiac
MOA
- not systemically absorbed
- bind to the fecal contents and pull water into the stool
- softens and lubricated the stool
- increased water in the stool makes it swell and increase in size- stimulates movement of the intestines
Onset of action
-12-24 hours but may take up to 3 days for full effect
SE
-flatulence, bloating, abd cramping, excessive use can cause n/v
CI
- esophageal stictures
- GI ulceration
- strictures anywhere along GI tract or obstruction
Special considerations
- Celiac pts need specific gluten free formulation
- Caution in DM (some can have a lot of sugar)
- Fibercon can decrease the absorption of tetracycline and quinolones
Ducosate Derivatives aka MOA Drugs Use SE
AKA
-Surfactant laxatives or “stool softeners”
MOA
- reduced surface tension of the liquid contents of the bowel
- no systemic absorption
Drugs
- Colace (Ducosate sodium)
- Surfak (Ducosate calcium)
Use
- good for pts who should not strain with BM or for those on narcotics
- only PREVENTS constipation, does not TREAT constipation
SE
- overall very well tolerated
- stomach upset MC
- mild abd cramping, diarrhea
First line treatments
bulk forming
surfactant laxatives
Second line treatments
Phillips Milk of Magnesia
Magnesium sulfate (epsom salt)
Lactulose
Sorbitol
Magnesium Hydroxide (MOM) AKA MOA Onset of action SE
AKA
-Saline Laxative, Milk of Magnesia
MOA
-draws water into the bowel through osmosis, increases intraluminal pressure and motility
Onset of action
-rapid
SE
- GI upset, diarrhea
- dehydration is a concern if excessive use
Lactulose (Kristalose) (Sorbitol) class Use MOA routes SE
Class
-Hyperosmotic laxitives
Use
- if failed bulk forming agents and failure of magnesium hydroxid (MOM)
- use with caution in DM (soultion contain galactose and lactose)
MOA
- metabolized to soultes and increase osmotic pressure by drawing in fluid from less concentrated areas
- increased pressure stimulates intestinal motility
Routes
-can be PO or enema
SE
- GI upset
- diarrhea
- flatulence
Third line therapy
stimulant laxatives
mineral oil
sodium biphosphates
magnesium citrate
castor oil
Stimulant laxatives
- drugs
- duration of use
- MOA
- Onset of Action
- SE
- CI
Drugs
- Senna (Senokot)
- Bisacodyl (dulcolax)
Duration of use
-not for long term use
MOA
- increase peristalsis through direct effects on the smooth muscle of the intestines
- promote fluid accumulation in the colon an small intestine
Onset
- 15 min to 2 hours PR
- 6-10 hrs PO
SE
- n/v abdominal cramping
- recatl fissures and hemorrhoids
CI
-surgical abdomen, fecal impaction
