Understanding Selpercatinib and Its Role
Selpercatinib, sold under the brand name Retevmo®, is a targeted cancer therapy belonging to a class of drugs known as kinase inhibitors. It is specifically a RET inhibitor, which means it works by blocking the action of an abnormal protein encoded by the rearranged during transfection (RET) gene. Certain mutations or fusions in the RET gene can cause cancer cells to grow and multiply uncontrollably. By selectively inhibiting this protein, selpercatinib helps to slow or stop the spread of cancer cells.
This medication is prescribed for specific types of cancers that have a RET gene alteration, including:
- Non-small cell lung cancer (NSCLC)
- Medullary thyroid cancer (MTC)
- Other types of thyroid cancer
- Various solid tumors
Before starting treatment, a doctor will perform a test to confirm the presence of an abnormal RET gene to ensure the patient is a candidate for this therapy. Treatment typically continues until the disease progresses or the patient experiences unacceptable toxicity.
How is Selpercatinib Administered?
Selpercatinib is an oral medication that comes in capsule and tablet form. It is crucial to follow the prescribing doctor's instructions precisely.
Core Administration Instructions:
- Dosage Frequency: It is usually taken twice daily, approximately every 12 hours. In some younger pediatric patients, a three-times-daily schedule may be prescribed based on the healthcare provider's assessment.
- With or Without Food: Selpercatinib can generally be taken with or without food. However, there are important exceptions when taken with certain other medications (see Drug Interactions section).
- How to Take: The capsules and tablets must be swallowed whole. They should not be crushed, chewed, opened, or split. Patients who are unable to swallow the capsule whole should discuss alternative options with their healthcare provider.
- Missed Dose: If a dose is missed, it should be taken as soon as remembered. However, if it is less than 6 hours until the next scheduled dose, the missed dose should be skipped entirely, and the regular schedule should be resumed. A double dose should never be taken to make up for a missed one.
- Vomiting: If vomiting occurs after taking a dose, another dose should not be taken. The patient should wait until the next scheduled dose.
Determining the Appropriate Dose
The specific dose of selpercatinib is determined by a healthcare professional based on individual factors such as the patient's age, body size, and overall health.
Factors Influencing Dosage:
- Age and Weight/Body Surface Area: Dosage calculations differ for adults, older children (12 and above), and younger children (2 to under 12). Adult dosing is typically based on body weight, while pediatric dosing for younger children is based on body surface area.
- Response to Treatment and Side Effects: The healthcare provider will monitor how the patient responds to the medication and any side effects experienced. Adjustments to the dose may be made to optimize treatment outcomes and manage adverse reactions.
- Other Health Conditions: Existing medical conditions may influence the appropriate starting dose or necessitate dose adjustments.
A healthcare provider may adjust the dose based on how well the medication is working and any side effects experienced.
Important Considerations and Drug Interactions
Certain medications can interact with selpercatinib, affecting how it is absorbed and its concentration in the blood. Special administration timing is required for acid-reducing agents.
| Medication Type | Administration Instruction with Selpercatinib | Rationale |
|---|---|---|
| Proton Pump Inhibitors (PPIs) (e.g., omeprazole, lansoprazole) | Take selpercatinib with food. | PPIs reduce stomach acid, which can decrease the absorption of selpercatinib. Taking it with food helps counteract this effect. |
| H2 Blockers (e.g., famotidine, cimetidine) | Take selpercatinib at least 2 hours before or 10 hours after the H2 blocker. | This timing separation is necessary to avoid reduced absorption of selpercatinib due to changes in stomach acidity. |
| Antacids (containing aluminum, calcium, magnesium) | Take selpercatinib at least 2 hours before or 2 hours after the antacid. | Locally-acting antacids can interfere with absorption; this time window prevents that interaction. |
Patients should also avoid grapefruit and St. John's Wort, as they can interfere with the medication. It is essential to inform the healthcare team of all medications, including prescriptions, over-the-counter drugs, vitamins, and herbal supplements.
Managing Side Effects and Dose Adjustments
Selpercatinib is a powerful medicine that can cause side effects. Common side effects include dry mouth, diarrhea, fatigue, high blood pressure (hypertension), and elevated liver enzymes. More serious side effects can include liver toxicity, lung inflammation, and changes to heart rhythm (QTc prolongation).
To manage these, a doctor may recommend:
- Dose Reduction: If a patient experiences significant adverse reactions, the doctor may reduce the daily dose based on established guidelines. The specific reduction steps are determined by the healthcare provider based on the severity of the side effect. In some cases, if dose reductions are not sufficient to manage side effects, the medication may be discontinued.
- Treatment Interruption: For certain side effects, like severe liver enzyme elevation (hepatotoxicity) or before a planned surgery, a doctor may temporarily stop treatment. Treatment is typically recommended to be stopped at least 7 days before surgery and withheld for at least 2 weeks after to ensure proper wound healing.
- Supportive Care: For side effects like diarrhea or nausea, dietary changes and other medications can be prescribed. Regular monitoring of blood pressure, liver function, and electrolytes is a standard part of treatment.
Conclusion
Administering selpercatinib correctly is vital for its effectiveness and safety. It is taken orally, typically twice a day, with dosage determined by a healthcare provider based on factors like age and body size. Patients must swallow the medication whole and adhere to specific timing rules if also taking acid-reducing agents. Close communication with a healthcare team is essential for monitoring response, managing side effects through potential dose adjustments, and ensuring the best possible outcome for patients with RET-altered cancers.
For more information, patients can review materials from the manufacturer. Retevmo® (selpercatinib) Information
