In my limited understanding, one need to differentiate a bulk drugs (or API) from forumlator. The real skill in pharma is mainly to manufacture bulk drugs. While novel drug delivery system (NDDS), is also an area of significant value addition, in domestic market, innovation are mostly in API then with forumlator (except some higher end products like insulin injections/ asthma pumps).
BDH in my limited understanding has forumlation capacity (tablet/capsule/ syrup etc) then bulk drug capacity. Hence, they can buy drug and convert in tablet. While approval with WHO and other authorities are important factors, but still, bulk drug of HCQ would be major beneficiary (even assuming Government does not control price).
So in my limited understanding, BDH is unlikely to gain majorly due to COVID crisis due to HCQ. Having said that, change in Pharmaceutical sector perception and decline price may be positive and I have no view on same.
Discl: No investment, Not SEBI registered investment advisor, Not recommending.