The brand name could be used to sell anything, which comes under the established brand personality.
For example, the Burnol brand name could be used to sell an antiseptic like Dettol.
Buying a brand provides a ready-made market. Apparently, Ranbaxy bought Mox because its own brand in the name family, Amoxycillin was not doing too well.
Buying a brand saves a lot of brand building time and cost.
Drug companies are known to recoup the cost of acquiring a brand in less than four years.