Dear Manish Gupta,
This is one of the toughest challenges for an HR professional in the industry. You should refer to the link below for some ideas that can be presented in a PowerPoint form to employees. Additionally, I have a suggestion. I am not sure how it will be received, but you can discuss it with the management. My proposal is to provide an increment of 200 Rs to 500 Rs to employees who do not have any drug habits. It should be communicated that a company medical practitioner will conduct monthly checks, and if an employee is found to have lied, any increment given to them as per this policy will be revoked.
http://rctfi.org <link updated to site home>