GERD, Prokinetic, Anti-emetic and Antidiarrheal drugs Flashcards
What is GERD (gastroesophageal reflux disease)?
Abnormal relaxation of the LES (lower esophageal sphincter) – a circular band of muscle at the bottom of the esophagus allows the stomach acid into esophagus
–stomach acid in the esophagus affects the GERD symptoms
What are some non pharmological treatment of GERD?
Small meals Weight loss Avoid bed time acid rich drinks Elevated head of the bed to 6-8 inches lifestyle modifications (smoking and drinking)
What drugs are used for GERD?
Antacids
PPI +/- H2 blockers
Prokinectic drugs are used in GI disorders, what does this mean?
Relieve GI symptoms of abdominal discomfort, bloating, heart burn, nausea, vomiting, that could be associated with GERD or gastroparesis or GI movement disorders
What are the Prokinetic disorders used in GI disorders?
Metoclopramide
5HT4 agonists
Cholinomimetics
Macrolides
First up is metoclopramide, what is the MOA and therapeutic uses?
MOA:
–5HT3 and D2 receptor blocker (acts as anti-emetic)
accelerates gastric emptying and intestinal motility
Therapeutic Uses:
–diabetic, post op gastroparesis and relief of symptoms in GERD
What are the adverse effects of Metoclopramide?
Anti-dopaminergic:
–sedation, diarrhea, and parkinsonian effects limit its high doses and long term use
The next prokinetic drug is Cisapride. What is this drug and the side effects?
5HT4 agonist
Uses: gastroparesis, GERD, and constipation via stimulating Ach
Side effects: Arrhythmias (not used anymore)
The next prokinetic effect drug are the Cholinomimetics: Neostigmine and Bethanechol. what are their uses?
Neostigmine:
–used in the colonic pseudo-obstruction in hospitalized patients
Bethanechol:
–resistant to cholinesterase; long duration of action, used in post operative bowel and bladder atony
Finally the last prokinetic agent to discuss are the Macrolides. What is their use?
Erythromycin acts on motilin receptors of GIT used IV
- -used for gastric emptying before upper GI endoscopic procedures
- -tolerance may develop in gastroparesis
Moving on to Emesis: what is this?
Vomiting or throwing up is an involuntary, forceful expulsion of contents of stomach through the mouth or sometimes from nose
Review the Emesis diagram number 49 of the GI slides (pharm)
1.Sensory input (pain, smell, sight) as well as memory, fear and anticipation all are factors that act on the HIGHER CORTICAL CENTERS and lead to n/v
2.D2, 5HT3 (GI distention, or acute GI infection activates the 5HT3) ,Opioid/Ach and substance P receptors as well as chemotherapy is the CHEMORECEPTOR TRIGGER ZONE (AREA PROSTREMA 4TH VENTRICLE) (outside of BBB)
3. Chemotherapy and Radiotherapy act on the STOMACH AND SI and lead to n/v
4. Muscarinic and H1 receptors act on LABYRINTHS (this is responsible for motion sickness)
ALL 4 of these bolded centers act on the medulla which is the vomiting center
What are the major categories of antiemetics?
- 5HT3 inhibitors
- H1 antihistamines and antimuscarinics
- NK1 receptor blockers
- Corticosteriods
- D2 receptor antagonist
- Benzamide
- Metoclopramide
- Cannabinoids
First anti-emetic drug is Ondansetron, what is the MOA and clinical indications?
MOA:
–block 5HT3 in the gut and CNS
Clinical indications:
–chemotherapy induced–moderate to severe emesis or post operative nausea and vomiting
–route of administration usually IV and for prophylaxis they are given orally
2nd anti-emetic drug are the H1 antihistamines and Antimuscarinics. What are these drugs?
H1 antihistamines: Diphenhydramine, Cyclizine and Meclizine: used in motion sickness and chemotherapy induced sickness
Antimuscarinics: Scopolamine: effective in emesis due to motion sickness