patisiran patisiran patisiran, sold under the brand name onpattro, is a medication used for the treatment of polyneuropathy in people with hereditary transthyretin-mediated amyloidosis, a fatal rare disease that is estimated to affect 50,000 people worldwide. patisiranclinical datatrade namesonpattroother namesaln-18328ahfs/drugs.commonographlicense data us dailymed: patisiran pregnancycategory au: d routes ofadministrationintravenousatc coden07xx12 (who) legal statuslegal status au: s4 (prescription only) ca: ℞-only us: ℞-only eu: rx-only identifierscas number1420706-45-1drugbankdb14582unii50fkx8cb2ykeggd11116as salt: d10794chemical and physical dataformulac412h520n148o290p40molar mass13424.388 g·mol−1 it is the first small interfering rna-based drug approved by the u.s. food and drug administration (fda) and the first drug approved by the fda to treat this condition. it is a gene silencing drug that interferes with the production of an abnormal form of transthyretin. patisiran utilizes a novel approach to target and reduce production of the ttr protein in the liver via the rnai pathway. patisiran was developed and is marketed by alnylam. the fda considers it to be a first-in-class medication. history patisiran was granted orphan drug status, fast track designation, priority review and breakthrough therapy designation due to its novel mechanism and the rarity of the condition it treats. it was approved for medical use in the united states and in the european union in august 2018. the per-patient cost is between us$451,430 and us$677,145 per year, depending on the number of vials needed. formulation the sirna active component of patisiran is formulated into lipid nanoparticles, which protect the rna and facilitate its delivery to target tissues. the lipid nanoparticle formulation includes buffer components, as well as the lipid components dlin-mc3-dma, distearoylphosphatidylcholine, cholesterol, and the pegylated lipid dmg-peg 2000. society and culture economics as of 2020, there were 1050 people globally receiving patisiran, generating $65.5m in net-revenues for alnylam pharmaceuticals.