Source published 19 October 2026 by MHRA news (GOV.UK)
Key Takeaways
- The Medicines and Healthcare products Regulatory Agency (MHRA) has authorised plozasiran (Redemplo) as an adjunct to a low-fat diet for adults with familial chylomicronaemia syndrome (FCS).
- Plozasiran acts by inhibiting hepatic production of apolipoprotein C3, thereby lowering circulating triglyceride levels.
- The therapy is delivered as a 25 mg subcutaneous injection administered once every three months.
- In a key trial of 75 adults, plozasiran achieved an approximate 80% median reduction in triglycerides at 10 months compared with 17% for placebo, with fewer acute pancreatitis events observed.
- The most common adverse reaction is hyperglycaemia (affecting more than 1 in 10 patients); other common effects include headache, nausea, and injection-site reactions.
MHRA Authorisation and Regulatory Route
On 19 October 2026, the MHRA granted marketing authorisation for plozasiran (Redemplo) to treat adult patients with familial chylomicronaemia syndrome. The licence was awarded to Arrowhead Pharmaceuticals Ireland Limited through Route B of the International Recognition Procedure (IRP), relying on assessments from the European Medicines Agency (EMA) as the reference regulator.
The regulatory agency evaluated the therapy to assess whether its therapeutic benefits outweigh potential clinical risks. Product information, including the Summary of Product Characteristics (SmPC) and the Patient Information Leaflet (PIL), will be made available via the MHRA Products website.
Clinical Indication and Mechanism of Action
Familial chylomicronaemia syndrome is a rare metabolic disorder characterised by severely elevated levels of serum triglycerides. In clinical practice, this extreme hypertriglyceridaemia places patients at serious risk of acute pancreatitis, an inflammatory condition presenting with severe abdominal pain that can lead to life-threatening systemic complications.
Plozasiran is indicated specifically to lower triglyceride concentrations alongside dietary fat restriction. The drug functions by reducing the synthesis of apolipoprotein C3 in the liver.
Because apolipoprotein C3 naturally inhibits the clearance and breakdown of plasma fats, suppressing its production facilitates the clearance of circulating triglycerides.
The approved dosing regimen consists of a 25 mg subcutaneous injection administered once every three months. Following appropriate training, the injection may be given either by the patient or by a designated caregiver.
Clinical Evidence and Pancreatitis Outcomes
The MHRA decision is based on data from a primary clinical study evaluating 75 adult patients diagnosed with FCS. Throughout the investigation, all participants maintained a controlled diet; 50 participants received plozasiran, while 25 were assigned to a placebo control group.
At the 10-month evaluation point, patients in the plozasiran arm exhibited a median reduction in triglyceride levels of approximately 80%, compared with a 17% reduction observed in the placebo group. In addition to biochemical lipid lowering, clinical investigators documented fewer episodes of acute pancreatitis among patients receiving active treatment.
Commenting on the regulatory approval, Julian Beach, Executive Director of Operations at the MHRA, stated: "This authorisation provides an additional treatment option for adults with familial chylomicronaemia syndrome, a rare condition that can cause serious and painful complications. Clinical trial data showed that plozasiran substantially reduced triglyceride levels when used alongside a controlled diet.
As with all medicines, we will continue to monitor the safety of plozasiran closely."
Safety Considerations and Adverse Reaction Reporting
The primary adverse reaction identified in clinical trials was hyperglycaemia, which occurred in more than 1 in 10 individuals receiving the medicine. Other adverse effects reported at lower frequencies (affecting up to 1 in 10 patients) included nausea, headache, and localised injection-site reactions.
Healthcare professionals and patients are advised to monitor for potential treatment-related side effects. Any suspected adverse drug reactions should be reported via the MHRA Yellow Card scheme or through the Yellow Card mobile application to facilitate ongoing post-authorisation safety surveillance.
Source: MHRA news (GOV.UK)
