What happened

This surely won't be a week to remember for Amarin (AMRN -0.94%). Following Monday's stinging Supreme Court loss regarding patent protection for its one and only commercialized drug, on Tuesday one of the company's rivals announced the launch of a new generic for that product. Amarin's shares fell by 3.2%.

So what

The ruling scotched Amarin's attempt to dispute a lower court's decision that its core patents on the drug, Vascepa, were invalid. So now that they are entirely free to make Vascepa generics without worrying about a legal reversal, pharmaceutical companies eagerly continue to do so.

On Tuesday Dr. Reddy's Laboratories (RDY -2.55%) formally launched its icosapent ethyl capsules, which will be available in 120-count bottles of 1-gram capsules. This product was approved by the Food and Drug Administration (FDA) last August.

Person about to ingest medication.

Image source: Getty Images.

Dr. Reddy's, not coincidentally, was one of the two generic-drug makers (along with Hikma Pharmaceuticals) embroiled in that original patent protection case against Amarin. Hikma rolled out its own icosapent ethyl capsules last November.

Many pharmaceutical industry experts consider Vascepa to be a potential blockbuster drug. Derived from fish oil, it has been shown to be quite effective in treating patients with elevated triglyceride levels.

Now what

The Dr. Reddy's rollout is a fresh nail in the coffin for Amarin's big Vascepa dreams in the U.S. While the branded drug still has great potential, this will have to be realized in a collection of markets abroad rather than this one massive and lucrative country.