peginterferon beta-1a peginterferon beta-1a peginterferon beta-1a', sold under the brand name plegridy, is medication used to treat multiple sclerosis. peginterferon beta-1aclinical datatrade namesplegridy, plegridy penahfs/drugs.commonographmedlineplusa614059license data eu ema: by inn us dailymed: peginterferon_beta-1a pregnancycategory au: d routes ofadministrationsubcutaneous injectiondrug classantineoplastic agentatc codel03ab13 (who) legal statuslegal status au: s4 (prescription only) us: ℞-only eu: rx-only in general: ℞ (prescription only) identifiers iupac name 1-ether with n-(3-hydroxy-2-methylpropyl)interferon β-1a (human) α-methyl-ω-hydroxy-poly(oxy-1,2-ethanediyl) cas number1211327-92-2drugbankdb09122uniii8309403r0keggd10483chemical and physical dataformulac913h1417n246o256ps7 nmolar mass44 000 g·mol−1 the most common side effects include headache, muscle pain, joint pain, influenza (flu)-like symptoms, pyrexia (fever), chills, asthenia (weakness), and erythema (reddening of the skin), pain or pruritus (itching) at the injection site. peginterferon beta-1a was approved for medical use in the united states and in the european union in 2014. medical uses in the united states peginterferon beta-1a is indicated for the treatment of relapsing forms of multiple sclerosis (ms), to include clinically isolated syndrome, relapsing-remitting disease, and active secondary progressive disease, in adults. in the european union peginterferon beta-1a is indicated for the treatment of relapsing remitting multiple sclerosis in adults.