The present invention relates to a pharmaceutical composition comprising glucosylceramide synthase inhibitor and a one or more pharmaceutically acceptable excipients. The present invention specifically relates to a sublingual pharmaceutical composition of eliglustat or a pharmaceutically acceptable salt thereof and a one or more pharmaceutically acceptable excipients. Moreover, the present invention further relates to a pharmaceutical composition of eliglustat or a pharmaceutically acceptable salt thereof which is used in the treatment of individual with lysozymal storage diseases selected from the group consisting of, Gaucher disease, Sphingolipidoses, Farber disease, Krabbe disease, Fabry disease, Schindler disease, Tay-Sachs disease and Niemann-Pick disease.
