March 26 (Bloomberg) — Abandoning a long-held industry tradition, GlaxoSmithKline Plc and Merck & Co. won't help low-income Obamacare patients pay for their high-priced drugs.

The drugmakers say they won't provide the assistance until the government decides whether programs overseen by the U.S. health-care act are subject to federal laws banning kickbacks that steer business to companies. So far, U.S. agencies have sent mixed messages on the issue, industry officials said.

Historically, drugmakers use coupons and debit cards to encourage the use of high-priced medicines rather than less expensive older treatments and generics pushed by insurers using high co-pays as a cudgel. In the case of Amgen Inc.'s Neulasta for chemotherapy patients, the company pays as much as $10,000 a year to help patients get the medicine. Amgen is among a group of companies continuing their aid programs.