Antiemetic and Antinausea Drugs Flashcards
Nausea
Vomiting
Antiemetic drugs
Nausea
Sensation often leading to the urge to vomit
Emesis (vomiting)
Forcible emptying of gastric and, occasionally, intestinal contents
Antiemetic drugs
Used to relieve nausea and vomiting
Vomiting Centre and Chemoreceptor Trigger Zone
- Location
- What happens when its stimulated?
Vomiting centre
Chemoreceptor trigger zone (CTZ)
-Both located in the brain
-Once stimulated, cause the vomiting reflex
3 Types of Nausea and Vomiting
Chemotherapy induced
Postoperative
General
7 Antiemetics and Antinausea Drugs
Anticholinergic drugs
Antihistamines (histamine 1 [H1] receptor blockers)
Antidopaminergic drugs
Neurokinin ANTAGONISTS
Prokinetic drugs
Serotonin BLOCKERS
Tetrahydrocannabinoids
Antiemetics and Antinausea Drugs: Mechanism of Action
Many different mechanisms of action
Most work by blocking one of the vomiting pathways, thus blocking the stimulus that induces vomiting.
Site of action of Antinausea drugs
Labyrinth (inner ear)
-Anticholinergics
-Antihistamine
-Neuroleptics
-Prokinetic
GI Tract
-Prokinetic
-Serotonin Blockers
Cerebral Cortex
-Tetrahydrocannabinol (THC)
-Corticosteroids
-Benzodiazepines
Vomiting Centre (Medulla)
-Serotonin Blockers
Chemoreceptor Trigger Zone (CTZ)
-Neuroleptocs
-Prokinetic
-Serotonin Blockers
Antiemetic Indications
Specific indications vary per class of antiemetics.
General use for each type: prevention and reduction of nausea and vomiting
Anticholinergic drugs (acetylcholine blockers)
- 1 medication
- Mechanism of action
scopolamine
Bind to and block acetylcholine receptors in the inner ear labyrinth
Block transmission of nauseating stimuli to CTZ
Also block transmission of nauseating stimuli from the reticular formation to the vomiting centre
Antihistamine drugs (H1 receptor blockers)
- 2 medications
- Mechanism of action
- Also used for? (4)
dimenhydrinate (Gravol®)
diphenhydramine (Benadryl®)
Inhibit acetylcholine by binding to H1 receptors
Prevent cholinergic stimulation in vestibular and reticular areas, thus preventing nausea and vomiting
Also used for motion sickness, nonproductive cough, allergy symptoms, sedation
Antidopaminergic drugs
- 1 medication
- Mechanism of action
prochlorperazine (Proclorazine®)
Block dopamine receptors in the CTZ
Also used for psychotic disorders, intractable hiccups
Neurokinin receptor antagonists
- 1 medication
- Mechanism of action
- Used in conjuction with _____ and _______
- Use augments the? why?
aprepitant (Emend®)
Inhibit substance P/neurokinin 1 receptors in the brain stem
Used in conjunction with serotonin blockers and glucocorticoids
Use augments the serotonin blockers and glucocorticoids to inhibit acute and delayed phases of chemotherapy-induced emesis
Prokinetic drugs
- 1 medication and its long term use effect
- Mechanism of action
- Also stimulates
- Also used of
metoclopramide (Metonia®)
-Long-term use may cause irreversible tardive dyskinesia (movement disorder)
Block dopamine receptors in the CTZ
Cause CTZ to be desensitized to impulses it receives from the gastrointestinal tract
Also stimulate peristalsis in gastrointestinal tract, enhancing emptying of stomach contents
Also used for gastroesophageal reflux disease, delayed gastric emptying
Serotonin blockers
- 1 medication
- Mechanism of action
ondansetron (Zofran®)
Block serotonin receptors in the gastrointestinal tract, CTZ, and vomiting centre
Used for nausea and vomiting in patients receiving chemotherapy and for postoperative nausea and vomiting
Tetrahydrocannabinoids
- Major psychoactive substance in ________
- Mechanism of action
- 1 medication
- Used for nausea and vomiting associated with?
Major psychoactive substance in marihuana
Inhibitory effects on reticular formation, thalamus, cerebral cortex
Alter mood and body’s perception of its surroundings, which may help relieve nausea and vomiting
Medical marihuana
Used for nausea and vomiting associated with chemotherapy and for anorexia associated with weight loss in (AIDS) patients
2 Miscellaneous Antinausea Drugs
aprepitant
doxylamine succinate
pyridoxine hydrochloride
doxylamine succinate
pyridoxine hydrochloride
doxylamine succinate- (used for morning sickness with pregnancy)
Pyridoxine hydrochloride (combination known as Diclectin – used for morning sickness – N & V - during pregnancy)
Antiemetic Adverse Effects
Vary according to drug used
Stem from their nonselective blockade of various receptors
Ginger
- Used for
- Adverse effects
- Drug interactions
Used for nausea and vomiting, including that caused by chemotherapy, morning sickness, and motion sickness
Adverse effects
Anorexia, nausea and vomiting, skin reactions
Drug interactions
May increase absorption of oral medications
Increase bleeding risk with anticoagulants
Nursing Implications
Assess complete nausea and vomiting history, including precipitating factors.
Assess current medications.
Assess for contraindications and potential drug interactions
Monitor therapeutic effects.
Watch for and monitor adverse effects.
Important to teach?
Many of these drugs cause severe drowsiness; warn patients about driving or performing any hazardous tasks.
Taking antiemetics with alcohol may cause severe central nervous system depression.
Teach patients to change positions slowly to avoid hypotensive effects.
For chemotherapy, antiemetics are often given 30 to 60 minutes before chemotherapy begins.
IV antiemetic schedule
30 minutes before chemo
prokinetic drugs are also used for?
delayed gastric emptying
aprepitant
this drug may not help more severe nausea caused by chemo
marihuana therapy
useful for N & V due to chemo
stimulate apetite due to nutritional wasting
may cause drowsiness and euphoria
