Announcement of Launch in Japan of RAVICTI® Oral Liquid 1.1 g/mL

Announcement of Launch in Japan of RAVICTI^® Oral Liquid 1.1 g/mL

Tokyo, Japan —April 15, 2026— OrphanPacific, Inc. (Head Office: Minato-ku, Tokyo; President and Representative Director: Megumi Hara) today announced that RAVICTI® Oral Liquid 1.1 g/mL (generic name: glycerol phenylbutyrate), indicated for the treatment of urea cycle disorders (UCD), has been listed on the Japanese National Health Insurance (NHI) drug price list and launched in Japan today.

RAVICTI® obtained marketing authorization in Japan on December 22, 2025. RAVICTI® is a prodrug of phenylbutyrate, formulated as an oral liquid that is easy to administer with minimal taste and odor. Even when the same amount of active ingredient (dose) as BUPHENYL® Tablets 500 mg and Granules 94% (generic name: sodium phenylbutyrate) is required, RAVICTI® allows patients to take a smaller volume of liquid due to its formulation characteristics, while providing comparable and sustained blood ammonia control. These features are expected to help reduce treatment burden and offer an additional therapeutic option for patients with UCD and their families.

Through the NHI price listing and launch of RAVICTI®, OrphanPacific aims to improve access to this treatment for patients in Japan and to help address unmet medical needs in the management of UCD. The company will continue to provide appropriate information to healthcare professionals to support the proper use of RAVICTI® and remains committed to the development and supply of medicines for

rare diseases, contributing to improved quality of life for patients and their families. Under an exclusive license agreement entered into with Immedica in May 2022, OrphanPacific is responsible for regulatory approval, commercialization, and local activities for RAVICTI® in Japan.

Summary of NHI Drug Price Listing and Launch

• About Urea Cycle Disorders (UCD)

The urea cycle, primarily in the liver, converts toxic ammonia produced in the body into non-toxic urea. UCD is a group of disorders caused by congenital defects in enzymes involved in this cycle, leading to hyperammonemia and symptoms such as vomiting, poor feeding, tachypnea, seizures, impaired consciousness, behavioral abnormalities, and developmental delays. In severe cases, it can be life-threatening. Most cases present in infancy, but some are diagnosed in adulthood. The estimated incidence is 1 in 8,000 to 44,000, and UCD is designated as an intractable disease in Japan.

Reference: Nanbyou Information Center (https://www.nanbyou.or.jp/entry/4732)

• About RAVICTI® (glycerol phenylbutyrate)

RAVICTI® is a medicine used to treat patients of all ages with UCDs, including deficiencies of carbamoyl phosphate synthetase I (CPS1), ornithine carbamoyltransferase (OTC), argininosuccinate synthetase (ASS), argininosuccinate lyase (ASL), arginase I (ARG1), ornithine translocase deficiency (ORNT1), and N-acetylglutamate synthase (NAGS) who cannot be managed by dietary protein restriction and/or amino acid supplementation alone. RAVICTI® must be used with dietary protein restriction and, in some cases, dietary supplements (e.g., essential amino acids, arginine, citrulline, protein-free calorie supplements). The medicine is used to reduce the amount of ammonia in the blood in order to reduce the risk of neurological consequences.

• About OrphanPacific, Inc.

OrphanPacific is a Japanese pharmaceutical company dedicated to the development, manufacturing, and marketing of drugs for rare diseases, thereby delivering new treatment options to patients with rare diseases. Our mission is “Bringing smiles and happiness to patients with rare diseases and their families.” With a commitment to “Leave No One Behind,” we are proactively engaged in the development and provision of therapies for rare diseases with extremely small patient populations.
OrphanPacific is a wholly owned subsidiary of CMIC Holdings (https://www.cmicgroup.com/), a pioneer and leading CRO (Contract Research Organization) in Japan. By leveraging the full breadth of CMIC Group’s expertise and experience in pharmaceutical development, manufacturing, and marketing, we strive to ensure that as many patients with rare diseases as possible have access to therapies. https://www.orphanpacific.com/

• About Immedica

Immedica is a pharmaceutical company, headquartered in Stockholm, Sweden, focused on the commercialization of medicines for rare diseases and specialty care products. Immedica’s capabilities cover marketing and sales, compliance, pharmacovigilance, quality assurance, regulatory, medical affairs and market access, as well as a global distribution network serving patients in more than 50 countries. Immedica is fully dedicated to helping those living with diseases which have a large unmet medical need. Immedica’s therapeutic areas are within RARE metabolic, RARE hematology & oncology, RARE neurology and specialty care. Immedica was founded in 2018 and employs today around 180 people across Europe, the Middle East and the United States. Immedica is backed by the investment firms KKR and Impilo.

For more information visit www.immedica.com.

Contact

OrphanPacific, Inc. Corporate Planning Department

Email: info@orphanpacific.com

Tel: 03-6779-8151