This has been clarified in Clause 6.8.1 h) of the MCI Act–

“Endorsement: A medical practitioner shall not endorse any drug or product of the industry publically. Any study conducted on the efficacy or otherwise of such products shall be presented to and/or through appropriate scientific bodies or published in appropriate scientific journals in a proper way”.

(Indian Medical Council (Professional Conduct, Etiquette and Ethics) Regulations, 2002)