Recently, the first oral drug- Risdiplam was approved by the FDA on 7 August 2020, for the treatment of spinal muscular atrophy (SMA) patients aged two months and older. SMA is a rare and common fatal genetic disease affecting muscle strength and movement.

Risdiplam encompasses a survival of motor neuron 2-directed RNA splicing modifier. Two clinical trials have investigated its efficacy in patients suffering infantile-onset and later-onset SMA. Twenty-one patients (mean age of 6.7 months) were included in infantile-onset SMA study. Efficacy was proved as per the ability to sit without support for at least 5 seconds and survival without lasting ventilation in this open-label study. As found, 41% of patients were able to sit individually for >5 seconds after a year of treatment. Also, 81% of patients were alive without lasting ventilation, which is an obvious improvement from characteristic disease progression without treatment after 23 or more months.

In the second randomized, placebo-controlled study, a total of 180 patients with SMA aged 2 to 25 years were included. The change from starting in MFM32 (a test of motor function) total score at the 1-year mark was regarded as the primary endpoint. The patients using Risdiplam had a 1.36 rise on an average in their score at the 1-year mark than a 0.19 decrease in patients on placebo (inactive treatment).

Rash, fever, diarrhoea, ulcers of the mouth area, joint pain and urinary tract infections (UTI) were frequently observed side effects of Risdiplam. Similar side effects were observed in cases of infantile-onset SMA and later-onset SMA. Additionally, UTI, pneumonia, vomiting and constipation were prevalent in infantile-onset.

As risdiplam may increase plasma concentrations of some drugs, therefore, patients should avoid taking risdiplam together with drugs that are multidrug and toxin extrusion substrates.

Risdiplam obtained orphan drug designation, which offers reasons to promote and boost drug development for rare disorders. The application was presented a Rare Pediatric Disease Priority Review Voucher.