Onpattro (patisiran) is a medication that treats the polyneuropathy symptoms of hereditary transthyretin-mediated (hATTR) amyloidosis, a rare, progressive, and fatal genetic disease. It works by using small interfering RNA (siRNA) encapsulated in a lipid nanoparticle to target and silence the production of the faulty transthyretin (TTR) protein in the liver. Consistent dosing is critical for managing this condition. All patients must receive premedication at least 60 minutes prior to each infusion to reduce the risk of infusion-related reactions (IRRs).
The Standard Onpattro Dosing Schedule
The standard dosing frequency for Onpattro is once every three weeks. This schedule is maintained over the long term to consistently suppress the production of the TTR protein. The specific dosage amount, however, is determined by the patient's actual body weight.
- For patients weighing less than 100 kg: The dosage is calculated based on body weight.
- For patients weighing 100 kg or more: A different dosage is used, regardless of further increases in weight.
This intravenous infusion is performed by a healthcare professional and typically takes about 80 minutes. While traditionally administered in a clinic or hospital setting, home infusion may be an option for some patients, pending a physician's evaluation.
Managing a Missed Onpattro Dose
Maintaining the every-three-week schedule is important for treatment efficacy. If a dose is missed, there is a specific protocol to follow based on when the missed dose is administered:
- If the dose is administered within 3 days of the missed dose: Continue dosing according to the patient's original schedule.
- If the dose is administered more than 3 days after the missed dose: Continue dosing every three weeks thereafter from the new administration date.
This ensures that treatment continues without significant interruption, even if there is a slight delay.
Onpattro vs. Other hATTR Amyloidosis Treatments
Onpattro is not the only treatment for hATTR amyloidosis. Other medications, such as Tegsedi (inotersen) and Amvuttra (vutrisiran), have different dosing schedules and administration methods. A comparison helps illustrate the differences in pharmacological approach.
| Feature | Onpattro (patisiran) | Tegsedi (inotersen) | Amvuttra (vutrisiran) |
|---|---|---|---|
| Dosing Frequency | Once every 3 weeks | Once every week | Once every 3 months |
| Administration Method | Intravenous (IV) infusion | Subcutaneous (SC) injection | Subcutaneous (SC) injection |
| Administered By | Healthcare professional | Can be self-administered at home | Healthcare professional |
| Dosing Calculation | Weight-based | Fixed dose | Fixed dose |
| Potential Risks | Infusion-related reactions | Serious bleeding or kidney problems | Infusion-related reactions, arthralgia |
Other Important Considerations
Beyond the administration schedule, patients on Onpattro need to be aware of other aspects of the treatment. One critical factor is the impact on vitamin A levels. Onpattro treatment can lead to a decrease in serum vitamin A levels, requiring daily supplementation. Patients should be advised to take a vitamin A supplement as recommended by their healthcare provider.
Additionally, infusion-related reactions (IRRs) are a potential side effect, affecting about 19% of patients in clinical studies. Symptoms may include flushing, back pain, nausea, or abdominal discomfort. The frequency of these reactions tends to decrease over time with continued treatment. The required premedication is crucial for minimizing these effects. For more detailed prescribing information, refer to the official FDA label for Onpattro.
Conclusion
The standard dosing for Onpattro is an intravenous infusion every three weeks, with the exact dose calculated based on body weight. This schedule is a core component of the treatment plan for hATTR amyloidosis. Adherence to the prescribed frequency, understanding the procedure for missed doses, and managing associated requirements like premedication and vitamin A supplementation are all essential for effective treatment. Patients should always work closely with their healthcare team to ensure the schedule and dosage are tailored to their specific needs.
