The present invention discloses a process for the synthesis of alkyl ester pro drugs of Ibuprofen of formula (I) and its encapsulation with polymeric nanoparticles for controlled drug release. More particularly, the present invention discloses a process for the synthesis of alkyl ester prodrugs of Ibuprofen of formula (I) from respective alcohols with increased pharmacological activity, low ulcerogenicity and good chemical stability. Further, the present invention discloses the study of said drug in vitro and in vivo controlled release pattern. Formula (I)