BANGKOK — When Thailand announced earlier this year that it was breaking patents on drugs to treat HIV and heart disease, Western pharmaceutical companies reacted with fury.

Abbott Laboratories, the maker of the AIDS drug Kaletra, took the radical step of withdrawing all of its new products from Thailand, depriving Thais of access to new drugs for rheumatoid arthritis, kidney disease, heart disease and high blood pressure.

"Thailand has chosen to break patents on numerous medicines, ignoring the patent system," said Jennifer Smoter, a spokeswoman for Abbott, which is based near Chicago. "As such, we've elected not to introduce new medicines there."

But two months after the uproar began, there are signs that Thailand has gained the upper hand. Its aggressive stance could be paving the way for other developing countries to extract lower drug prices from pharmaceutical giants in Europe and the United States.