Mumbai, June 8 : Pharma major Lupin on Monday said the US health regulator Food and Drug Administration (FDA) has granted Orphan Drug Designation (ODD) to its drug mexiletine hydrochloride for the treatment of myotonic disorders. The FDA grants ODD status to medicines intended for the treatment, diagnosis or prevention of rare diseases or disorders that affect fewer than 2 lakh people in the US. "The decision by the US FDA to grant orphan drug designation to mexiletine brings us closer to providing a licensed treatment option for patients in the US," Vinita Gupta, CEO, Lupin Limited, said in a statement. Myotonic disorders are a group of neuromuscular disorders characterised by a shared symptom called myotonia which is an inability to relax a contraction of skeletal muscle which originates from a voluntary muscular contraction such as shaking someone's hand and blinking, or everyday activities such as walking across a street and climbing stairs. Mumbai-based Lupin's drug NaMuscula (mexiletine hydrochloride) is the only licensed product to treat myotonia in adults with non-dystrophic myotonic (NDM) disorders. "We are pleased to have this opportunity to further our commitment to these patients," Gupta added. In April, the company had received an Establishment Inspection Report (EIR) from US FDA for its manufacturing plant in Nagpur. Lupin is the third-largest pharmaceutical company in the US by prescriptions and in India by global revenues. The company invests 9.6 per cent of its revenues on research and development. It has 15 manufacturing sites and seven research centres, with more than 20,000 professionals working globally. /IANS