MUMBAI (Reuters) - Indian drug maker Ranbaxy Laboratories Ltd. (RANB.BO: Quote, Profile, Research) will buy the unbranded generic business of GlaxoSmithKline Plc’s (GSK.L: Quote, Profile, Research) Italian division Allen S.p.a, the Indian company said on Monday. It said the deal will be effective from April 1. It did not indicate the value of the acquisition.