As a result the drug can enter the brain tissue.

Two earlier cases provide a glimpse of how illegal drugs can enter the system.

"Anything can happen when drugs enter the equation," said Banks.

In some cases, these drugs have entered the environment.

Once a drug enters the body, elimination and distribution begins.

Still, the potential for corruption has increased along with the volume of drugs entering the country, agency officials say.

The wounded man trembled slightly as the drug entered his system.

Having spent $80 million in developing the drug, the company wants to recoup its investment before new drugs enter the market.

The drug had entered clinical trials for treatment of anxiety and depression.

Mexico is a major source of drugs entering the United States.