Drug firms Takeda of Osaka, Japan, and Abbott Laboratories of Chicago, Illinois, are splitting up a joint venture begun in 1977.

Takeda, which may pay Abbott US$1.5 billion for the split, is expected to retain the heartburn drug Prevacid (lansoprazole), with Abbott taking the cancer drug Lupron (leuprolide). Both drugs had been produced through the joint venture TAP Pharmaceutical Products, based in Lake Forest, Illinois. Together, the two drugs accounted for around $3 billion in sales last year.