Antiemetic and Antinausea Drugs

Question 1

What are antiemetic drugs?

Answer 1

drugs given to relieve nausea and vomiting

Question 2

Whare are 4 types of antiemetic drugs?

Answer 2

Anticholinerguc drugs: Scopolamine (Scopace)

Antidopaminergic drugs: Promethazine (Phenegran)

Serotonin blockers: Ondansetron (Zofran)

Tetrahydrocannabinoids: Drobabinol (Marinol)

Question 3

Anticholinergics
- Mechanism of action
- Indications

Answer 3

MOA:
- bind to and block ACh receptors in the vestibular nuclei –> nausea-inducing signals can’t be transmitted to the chemoreceptor trigger zone (CTZ)

Indications:
- motion sickness
- secretion reduction before surgery
- nausea and vomiting

Question 4

Antidopaminergic
- Mechanism of action
- Indications

Answer 4

MOA:
- block dopamine receptors in the chemoreceptor trigger zone (CTZ)

Indications:
- psychotic disorders (mania, schizophrenia, anxiety)
- intractable hiccups
- nausea/vomiting

Question 5

Serotonin Blockers
- Mechanism of action
- Indications

Answer 5

MOA:
- block serotonin receptors located in the GI tract, chemoreceptor trigger zone (CTZ) and vomiting center
- specifically the 5 hydroxytryptamine 3 receptors are the site of action of the serotonin blockers like ondansetron

Indications:
- nausea/vomiting associated w/chemotherapy
- post-op nausea/vomit

Question 6

Tetrahydrocannabinoids
- Mechanism of action
- Indications

Answer 6

MOA:
- THC is the major psychoactive substance in marijuana; can be antiemetic because of its inhibitory effects on the reticular formation/thalamus/ and cerebral cortex; can also stimulate appetite

Indications:
- nausea/vomiting associated w/chemotherapy
- anorexia associated with weight loss in patients with AIDS and cancer

Question 7

Antiemetics Nursing Management

Answer 7

• assess complete nausea and vomiting history, including precipitating factors
• assess current meds
• many of the drugs cause severe drowsiness
• warn patients about driving or performing any hazardous tasks
• taking antiemetics with alcohol may cause severe CNS depression
• teach patients to change positions slowly to avoid hypotensive effects
• for chemotherapy antiemetics are often given 30 to 60 minutes before chemotherapy begins
• watch for fall precautions