The Ministry of Food and Drug Safety designated Nusinersen and Tacrolimus as orphan drugs Thursday, modifying regulations on its selection of rare disease therapies.

The change comes as part of the ministry’s efforts to increase the number of treatments available for patients with rare diseases who have no alternatives. Rare drug designations place the drug on a fast-track system which gives it priority review during the drug approval process.

Biogen’s Nusinersen, also known as Spinraza, is a biologic drug used to treat spinal muscular atrophy (SMA) – a rare neuromuscular disorder. Patients with the genetic disorder suffer from muscular dystrophy and weakness as well as difficulty breathing, sitting, and walking.

Nusinersen’s clinical trials conducted on infants with SMA showed children treated with the injections had significantly improved motor ability compared to those untreated.

The U.S. Food and Drug Administration approved the drug in December 2016 as the first drug for SMA. The drug has also gained approval in Europe, Japan, and Canada.

Tacrolimus is used to treat keratoconjunctivitis, or inflammation of the eye. Patients with keratoconjunctivitis experience eye irritation as well as sensitivity to light which causes burning and itching. The disease causes drying of the membrane which lines the eyelids and covers the white of the eye and the cornea.

Patients may use Tacrolimus eye drops when anti-allergic agents are ineffective.