ORLANDO, Fla. -

The U.S. Food and Drug Administration and Interpol took action this week against more than 4,100 internet pharmacies that have been illegally selling “potentially dangerous, unapproved or counterfeit drugs to consumers.“

The joint international investigation, called Operation Pangea V, shutdown roughly 18,000 illegal pharmacy websites and seized about $10.5 million worth of pharmaceuticals worldwide.

The Internet sweep ran from Sept.25 to this past Tuesday, Oct. 2.

“Consumers in the United States and around the world face a real threat from Internet pharmacies that illegally sell potentially substandard, counterfeit, adulterated or otherwise unsafe medicines,” said FDA Commissioner Margaret A. Hamburg, M.D. “This week’s efforts show that strong international enforcement efforts are required to combat this global public health problem.”

Among the illegal medicines identified through the operation were:

· Domperidone: This medicine was removed from the United States market in 1998 because it may cause serious adverse effects, including irregular heartbeat, stopping of the heart or sudden death.

· Isotretinoin (previously marketed as Accutane in the United States): This medicine is used to treat severe nodular acne and carries significant potential risks, including severe birth defects if pregnancy occurs while using this medicine.

· Tamiflu (oseltamivir phosphate): This medicine, which is used to treat the flu, is often sold online as “generic Tamiflu.” However, there is no FDA-approved generic version of Tamiflu. Previous FDA tests found that fraudulent versions of “generic Tamiflu” contained the wrong active ingredient, which would not be effective in treating flu.

· Viagra (sildenafil citrate): This medicine is used to treat erectile dysfunction. Due to its vasodilation effects, sildenafil citrate should not be used by consumers with certain heart conditions.

The FDA reports agents tracked other drugs used to treat high cholesterol, diabetes and high blood pressure already on the way to U.S. consumers. The FDA encourages consumers to report suspected criminal activity at www.fda.gov/oci.