Download (5-Hydroxytryptamine 3).

5-HT3 (5-Hydroxytryptamine 3)
Group 3
Drug Classifications/Indications for use (action)
Antiemetics – Used to prevent and treat nausea and vomiting.
Expected Outcome (Therapeutic Effect)
1. Verbal reports of decreased nausea
2. Decreased frequency or absence of vomiting
Subclasses (Names of different classes within this drug classification)
5-HT3 (5-Hydroxytryptamine 3)
Prototype: None
Ondansetron was first drug of this group. 4 drugs: ondansetron, granisetron, dolestron and palonsetron (all end in
TRON).
Polonsetron has the longest half-life (40 hours) and is given 30 minutes prior to chemotherapy in the same IV
access. Drug action begins rapidly
Characteristic Differences
h-Hydroxythrptamine3 (5-HT3) drugs are serotonin receptor antagonists. They are used to treat moderate to
severe nausea and vomiting associated with cancer chemotherapy, radiation therapy, and postoperative status.
These drugs antagonize serotonin receptors, preventing their activation by the effects of emetogenic drugs and
toxins.

In cancer chemotherapy, emetogenic drugs are thought to stimulate the release of serotonin from the
enterochromaffin cells of the small intestine; this released serotonin then activates 5-HT3 receptors located
on vagal afferent nerves in the CTZ to initiate the vomiting reflex.
o Emetogenic drugs- drugs having the capacity to induce vomiting
o Enterochromaffin cells - a type of enteroendocrine cell (specialized endocrine cells of the
gastrointestinal tract that produce hormones such as serotonin) occurring in the epithelia lining the
lumen of the digestive tract, duodenum of small intestines and the respiratory tract. Rare and slow
growing carcinoid tumors develop from these cells. When a tumor arises it has the capacity to
secrete large volumes of hormones.
o CTZ (chemoreceptor trigger zone) – Signals are relayed to the vomiting center in the medulla
oblongata by the activation of the chemoreceptor trigger zone. Receptors involved include
serotonin, dopamine, muscarinic.
Adverse Effects
Adverse effects are mild to moderate.
 Diarrhea
 Headache
 Dizziness
 Constipation
 Muscle aches
 Transient elevation of liver enzymes
o Transient - lasting only for a short time; impermanent
o What does elevation of liver enzymes mean - Any agent that damages the liver may cause elevation
of the liver enzymes
Top 3 Concerns w/Patient Care and Nursing Process
1. Administer antiemetic drugs 30 to 60 minutes before radiation therapy or cancer chemotherapy.
2. Some patients may experience less nausea and vomiting if they avoid or decrease food intake for a few
hours before scheduled chemotherapy.
3. The 5-HT3 receptor antagonists are usually considered the most effective antiemetics for chemotherapy.
Contraindications/Other
Children: Use caution when using 5-HT3 drugs. There are varying age/drug suitability issues and some cannot be
used in children under the age of 18. Recommended use of 5-HT3 receptor antagonists plus a corticosteroid
before administering chemotherapy to pediatric oncology pts.
 2 years of age and younger – do not use granisetron and dolasetron
 3 years of age and younger – little information available on effects of endansetron
 18 years of age and younger – do not use palonosetron
Hepatic Impairment: Use cautiously because these drugs are metabolized in the liver. Do not exceed 8 mg dose IV
or 8mg daily PO of ordansetron.