First do search which pharma company is developing it than mail them to provide gift sample. Also u can send them letter for gift sample forwarded by your head.
It may be due to covid-19 pandemics. Pharma sector is overloaded. it takes time to get gift samples from companies as transport facility is also under lockdown. its better, if you wait for some time and thn again send request to companies.
its better u may contact to your supervisor. He will surely guide and help You.