Can pantoprazole (Pantop) and ondansetron (Emeset) cause anaphylaxis?

Anaphylaxis Risk with Pantoprazole (Pantop) and Ondansetron (Emeset)

Yes, both pantoprazole (Pantop) and ondansetron (Emeset) can cause anaphylaxis, though it is rare with both medications.

Pantoprazole (Pantop) and Anaphylaxis

Risk and Evidence

• Pantoprazole is explicitly contraindicated in patients with known hypersensitivity to any component of the formulation or any substituted benzimidazole 1
• The FDA label specifically states that hypersensitivity reactions to pantoprazole may include anaphylaxis, anaphylactic shock, angioedema, bronchospasm, acute tubulointerstitial nephritis, and urticaria 1
• Multiple case reports have documented anaphylactic reactions to pantoprazole:
  • A 38-year-old female developed periorbital edema, skin edema, pruritus, nausea, vomiting, and breathing difficulty within 20 minutes of ingesting pantoprazole 40 mg 2
  • A 32-year-old female developed rashes, itching, and swollen lips and eyes after taking pantoprazole 40 mg 2
  • A 75-year-old female developed anaphylaxis within minutes of receiving intravenous pantoprazole 3

Cross-Reactivity with Other PPIs

• Cross-reactivity exists between different proton pump inhibitors 4
• In a study of 9 patients with omeprazole allergy, 4 also tested positive to pantoprazole on skin testing 4
• Lansoprazole may be better tolerated in patients with allergies to other PPIs 4

Ondansetron (Emeset) and Anaphylaxis

Risk and Evidence

• The FDA label for ondansetron clearly states that hypersensitivity reactions, including anaphylaxis and bronchospasm, have been reported in patients who have exhibited hypersensitivity to other selective 5-HT3 receptor antagonists 5
• The label recommends discontinuing ondansetron if hypersensitivity reactions occur and treating promptly per standard of care 5
• Ondansetron is contraindicated in patients with known hypersensitivity to the drug or any components of its formulation 5

Management of Suspected Anaphylaxis

Recognition of Anaphylaxis

Anaphylaxis typically presents with:

• Respiratory symptoms: bronchospasm, dyspnea
• Cutaneous manifestations: urticaria, angioedema, flushing
• Cardiovascular symptoms: hypotension, tachycardia
• Gastrointestinal symptoms: nausea, vomiting, abdominal pain 6

Immediate Management

1. Stop the suspected causative agent immediately
2. Maintain airway, breathing, and circulation
3. Administer epinephrine (first-line treatment)
4. Provide supplemental oxygen
5. Give intravenous fluids for hypotension
6. Consider H1 and H2 antihistamines and corticosteroids as adjunctive therapy 6

Prevention in High-Risk Patients

• For patients with a documented history of anaphylaxis to either medication:
  • Avoid the medication completely
  • Consider alternative drugs from different classes
  • If the medication is absolutely necessary, consider desensitization under specialist supervision 7
• Document the allergy clearly in the patient's medical records
• Educate patients about their allergy and provide them with information about alternative medications

Clinical Implications

For Pantoprazole (Pantop)

• Consider alternative acid-suppressing medications (H2 blockers or different PPIs) in patients with a history of hypersensitivity reactions
• If a PPI is necessary, lansoprazole may be a safer alternative in patients with pantoprazole allergy 4

For Ondansetron (Emeset)

• Consider alternative antiemetics from different classes in patients with a history of hypersensitivity reactions
• Monitor patients closely during first administration, especially those with a history of hypersensitivity to other 5-HT3 receptor antagonists

Important Considerations

• The risk of anaphylaxis should not prevent appropriate use of these medications in patients without a history of hypersensitivity
• Healthcare providers should be prepared to recognize and treat anaphylaxis promptly if it occurs
• Patients should be informed about the potential risk and advised to seek immediate medical attention if symptoms of hypersensitivity develop

Remember that while anaphylaxis is a serious concern, it remains a rare adverse effect with both medications, and the benefits of treatment often outweigh the risks in patients without known allergies to these drugs.