Pharmacology for Technicians PTCB Test Prep

PTCB Guide to Antiemetic Drugs

Dec 16th, 2023
ptcb guide to antiemetic drugs

What are antiemetic drugs?

Antiemetic drugs are medicines used to treat or prevent nausea and vomiting. “Antiemetic” takes its name from the word “emesis”, which is the medical term for vomiting.

There are many different causes of nausea and vomiting. Some of the most common include:

  • Motion sickness, vertigo
  • Hyperemesis gravidarum (morning sickness)
  • Chemotherapy
  • Side effects of some drugs, such as general anesthetics and opioid analgesics
  • Altitude sickness
  • Bulimia nervosa

Not all antiemetic drugs can be used to treat the same causes of nausea and vomiting.

Some antiemetic drugs are only used to treat motion sickness (antihistamines), whereas other antiemetic drugs are specifically used to treat nausea and vomiting caused by chemotherapy (5-HT3 receptor antagonists).

How should I prepare for the PTCB exam?

Note that pharmacy technicians are not expected to know each antiemetic drug class in detail.

Instead, technicians are expected to have a rounded knowledge of each drug class:

  • Identifying an antiemetic drug from a list of drugs.
  • Knowing what antiemetic drugs are used to treat.
  • Knowing the major brand names of the most prescribed antiemetic drugs.
  • Any serious adverse effects or drug interactions.
  • The broad outline of how each drug class works; its mechanism.

Antiemetic Drug Summary

Below, we have put together a table detailing each major drug class used as antiemetic drugs – example members of that class, as well as the major brand name of each drug.

Drug ClassExamplesBrand Names
(5-HT3 antagonists)
Dopamine antagonists
(antipsychotic drugs)
Bonine, Antivert
NK1 antagonistsAprepitant

What is each drug class used to treat?

  • Antihistamines tend to be used to treat motion sickness, morning sickness, and nausea and vomiting caused as a side effect of opioid analgesics.
  • 5-HT3 receptor antagonists – also known as “setrons” – are used to treat post-operative nausea and vomiting (PONV) and chemotherapy-induced nausea and vomiting (CINV).
  • NK1 receptor antagonists are also primarily used to treat PONV and CINV.
  • Benzodiazepines – such as midazolam – are effective at treating nausea and vomiting caused by general anesthesia. This antiemetic effect is enhanced if the benzodiazepine is given alongside a 5-HT3 receptor antagonist.
  • Dexamethasone is primarily used to treat PONV and CINV.
  • Dopamine antagonists are used to treat nausea and vomiting caused by cancer, chemotherapy, radiation sickness, and opioid toxicity.

PTCB Exam-Style Questions

Below, we have put together some practice PTCB exam questions on the topic of antiemetic medicines; testing all material covered in this article entry. You can find the answer to each question below. Go through each of these questions first and make a note of your answers.

Q1. Which of these antiemetic medicines works as an antagonist of serotonergic, 5-HT3 receptors?

a) Emend

b) Versed

c) Dramamine

d) Zofran

Q2. Patients with motion sickness are more likely to be prescribed a medicine from which class?

a) Antihistamines

b) Steroids

c) NK1 receptor antagonists

d) Dopamine antagonists

Q3. What is the active ingredient of the medicine, Benadryl?

a) Prochlorperazine

b) Dimenhydrinate

c) Palonosetron

d) Diphenhydramine

Q4. Setrons are most effective at treating nausea and vomiting from which of these causes?

a) Hyperemesis gravidarum

b) Altitude sickness

c) Vertigo

d) Chemotherapy

Q5. Medicines Compro and Zyprexa belong to which of these antiemetic drug classes?

a) NK1 receptor antagonists

b) Dopamine antagonists

c) Benzodiazepines

d) 5-HT3 receptor antagonists

Answer Key

These five questions represent the same style and difficulty of PTCB exam questions on the topic of antiemetic drugs. If you scored high, you can be confident that you already have a strong grasp of this medicine class.

Question 1: Zofran

Ondansetron is the active ingredient of the medicine, Zofran. Ondansetron works as an antagonist of serotonergic (serotonin-related) 5-HT3 receptors in the brain.

Question 2: Antihistamines

Antihistamines are considered among the first-line agents in the treatment of motion sickness and vertigo.

Examples include dimenhydrinate, diphenhydramine, and promethazine.

Question 3: Diphenhydramine

Diphenhydramine is the active ingredient of the medicine, Benadryl.

Question 4: Cancer chemotherapy

Setrons are most effective at treating nausea and vomiting due to cancer chemotherapy. Examples include granisetron and palonosetron.

Question 5: Dopamine antagonists

Prochlorperazine is the active ingredient of Compro, and olanzapine is the active ingredient of the medicine, Zyprexa. Both drugs work as dopamine antagonists, and both drugs also belong to the antipsychotic drug class.

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