The energy for an endergonic reaction is obtained by coupling the reaction with an exergonic reaction. A familiar example of coupling exergonic reactions to endergonic reactions to promote spontaneity comes from ATP.
That's a key distinction, because foreign countries with weak patent laws routinely inundate the market with knockoff products. The only way you're going to control your product in the market is if you have the ability to tell others to stop, Wolin says. In the United States and elsewhere, it's the patent system. That's the only way..
In addition, a patent on a changed compound does not prevent sales of the generic versions of the original drug unless regulators take the original drug off the market, as happened in the case of terfenadine. Patent protection allows the company to recoup the cost of developing that particular drug.