What is Palonosetron (Aloxi)?

Palonosetron (Aloxi) belongs to the class of drugs called serotonin (5-HT3) receptor antagonists. Serotonin is a naturally occurring chemical messenger that plays an important role in triggering nausea and vomiting.

Nausea and vomiting are common side effects experienced by patients undergoing chemotherapy or surgery. Palonosetron is an intravenous medication used to prevent nausea and vomiting associated with chemotherapy and surgery. Due to its long duration of action, it is effective in preventing both acute nausea and vomiting (within 24 hours) and delayed nausea and vomiting that may occur several days after chemotherapy.

What Drug Class Is Palonosetron?

Palonosetron is a serotonin (5-HT3) receptor antagonist. 

Blocking 5-HT3 results in the blockage of serotonin both peripherally, in the gastrointestinal tract, and centrally in the chemoreceptor trigger zone of the brain, which results in a strong antiemetic effect. 

Brand Name

Palonosetron is sold under the brand name, Aloxi.

What Is an Antiemetic Drug?

In medical terms, emesis is described as the process of vomiting. An antiemetic agent is a drug that is used to prevent nausea and vomiting.

What Is Palonosetron Used For?

Palonosetron is used to prevent acute and delayed nausea and vomiting associated with initial and repeat courses of chemotherapy. It is also used to prevent postoperative nausea and vomiting (PONV) in adults undergoing surgery. Because of its long half-life, palonosetron may provide protection against chemotherapy-induced nausea and vomiting for several days following treatment. 

5-HT3 receptor antagonists are FDA-approved medications used to prevent nausea and vomiting associated with chemotherapy, radiation therapy, and surgery.  For example, it may be used after receiving cancer-treating drugs (chemotherapy), undergoing radiation therapy, or experiencing nausea and vomiting associated with postoperative anesthesia.

Route of Administration and Strength 

Palonosetron (Aloxi) is available in the United States as an intravenous injection for the prevention of chemotherapy-induced and postoperative nausea and vomiting.

The drug comes in a sterile, clear, and colorless vial that contains 0.25 mg of drug per 5 ml. 

Dosage

In adults (17 years and older), palonosetron injection is given 30 minutes before the start of chemotherapy. The infusion is given over 30 seconds as a single 0.25 mg dose.  

In children from one month to less than 17 years of age, the injection is infused 30 minutes before the start of chemotherapy, and it is dosed at 20 micrograms per kilogram. Infusion is given over 15 minutes as a single dose.  

The dose of palonosetron injection given to prevent postoperative nausea and vomiting in adults is 0.075 mg IV administered 10 seconds immediately before administering anesthesia as a single dose.

Instructions Before Administration:

Before administering palonosetron injection:

• Visually examine the vial for any particulate matter or discoloration. If present, do not administer and discard immediately.
• Do not mix with any other medication.
• Before and after the administration, flush the infusion line with normal saline.  

What Are the Side Effects of Palonosetron?

Side effects vary from patient to patient. The two common side effects of palonosetron include:

• Headache
• Constipation

Serious side effects may include:

• Chest pain, severe dizziness, or symptoms of an abnormal heartbeat 
• Trouble breathing
• Fast or irregular heartbeat
• Allergic reactions, including swelling of the face, lips, tongue, or throat
• Hives or severe skin reactions
• Serotonin syndrome (a potentially life-threatening condition)
• Loss of coordination
• Muscle rigidity, twitching, or tremors
• Excessive sweating or shivering
• Agitation, confusion, or hallucinations

Although rare, patients experiencing symptoms of a serious allergic reaction or serotonin syndrome should seek immediate medical attention.

Is Palonosetron Chemotherapy?

No, it is an antiemetic drug given before chemotherapy to prevent nausea and vomiting.

Does Palonosetron Cause Constipation?

Constipation and headache are the most common side effects associated with palonosetron injection. If the condition gets severe, the patient should inform their doctor or pharmacist.

What Are the Best Anti-Nausea Medications for Chemotherapy?

The best anti-nausea medications for chemotherapy include:

• Ondansetron (Zofran)
• Palonosetron (Aloxi)
• Dolasetron (Anzemet)
• Granisetron (Kytril)

Palonosetron vs. Ondansetron

Several clinical studies have compared palonosetron and ondansetron for the prevention of chemotherapy-induced nausea and vomiting (CINV). Results suggest that palonosetron may provide better control of delayed CINV in certain patient populations and chemotherapy regimens, largely due to its longer half-life and stronger receptor binding.

Both medications are effective 5-HT3 receptor antagonists and are widely used in cancer care. The choice between palonosetron and ondansetron depends on factors such as chemotherapy regimen, risk of nausea and vomiting, cost, and institutional treatment protocols.

Contraindications

Palonosetron should not be given to patients with known hypersensitivity or allergy to palonosetron or any of its components.

Precautions

Serotonin Syndrome

Serotonin syndrome is when your body has too much serotonin. It usually occurs when patients use a combination of serotonergic drugs together, for example, SSRIs (selective serotonin reuptake inhibitors), SNRIs (serotonin and norepinephrine reuptake inhibitors), monoamine oxidase inhibitors, lithium, 5-HT3 receptor antagonists, fentanyl, or other antidepressants. 

Symptoms of serotonin syndrome should be monitored in patients while receiving palonosetron injection, as the condition can also occur without concomitant serotonin medication intake. Symptoms include:

• Mental instability issues like agitation, hallucination, or coma.
• Autonomic instability like tachycardia, irregular blood pressure, dizziness, and flushing.
• Neuromuscular problems like tremors, seizures, rigidity, or incoordination.
• Nausea, vomiting, and diarrhea.

Pregnancy and Breastfeeding

Limited data are available regarding the use of palonosetron during pregnancy. Palonosetron should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus.

It is not known whether palonosetron passes into human breast milk. Patients who are pregnant, planning to become pregnant, or breastfeeding should discuss the risks and benefits of treatment with their healthcare provider before receiving palonosetron.

Drug Interactions

Drugs that may interact with palonosetron include:

• Selective serotonin reuptake inhibitors (SSRIs), such as fluoxetine and sertraline
• Serotonin-norepinephrine reuptake inhibitors (SNRIs), such as venlafaxine and duloxetine
• Monoamine oxidase inhibitors (MAOIs)
• Tramadol
• Fentanyl
• Lithium
• Linezolid
• St. John’s Wort

Patients should inform their healthcare provider about all prescription medications, over-the-counter medications, vitamins, and herbal supplements before receiving palonosetron.

Half-Life

The elimination half-life of palonosetron is approximately 40 hours. This extended half-life contributes to its effectiveness in preventing delayed chemotherapy-induced nausea and vomiting.

Conclusion

Nausea and vomiting are common side effects of chemotherapy and surgery. Palonosetron hydrochloride is administered before chemotherapy or surgery to help prevent both acute and delayed nausea and vomiting. Its long half-life allows it to provide protection for several days following chemotherapy, making it an important option for the prevention of chemotherapy-induced nausea and vomiting.  It is typically administered as a single IV dose before chemotherapy or surgery.  Headache and constipation are the most common side effects of palonosetron. The drug should be used with caution during pregnancy, breastfeeding, and when there is a known allergy to palonosetron or any of its compounds. Additionally, drug use should be avoided or used with monitoring in patients receiving serotonergic drugs, especially antidepressants, and any other drugs known to interact with palonosetron.