International Isotopes Inc. Announces Execution of a Contract Manufacturing Agreement with Progenics Pharmaceuticals, Inc.

International Isotopes Will Manufacture Azedra® and Other Iodine Products Under a Manufacturing And Supply Agreement

Idhao Falls, Idaho, April 9, 2019 /PRNewswire/ -- International Isotopes Inc. (OTCQB: INIS) (the "Company") has announced it has executed a manufacturing and supply agreement with Progenics Pharmaceuticals Inc. ("Progenics"). Under this agreement, the Company will provide contract manufacturing services for AZEDRA® (Ultratrace® Iobenguane I-131) and other iodine products.

Steve T. Laflin, President and CEO of the Company, said, "We are very pleased to have an opportunity to enter into this manufacturing and supply agreement with Progenics. Contract manufacturing for Progenics builds upon our license qualifications and experience in handling iodine-131 and helps further broaden our customer base and technical experience. Speaking for the entire team at the Company, we certainly welcome this new opportunity and look forward to a long and beneficial relationship with Progenics."

About AZEDRA

Progenics had previously announced U.S. Food and Drug Administration ("FDA") approval of AZEDRA in July 2018. AZEDRA is the first and only approved therapy in the U.S. for the treatment of adult and pediatric patients 12 years and older with iobenguane scan positive, unresectable, locally advanced or metastatic pheochromocytoma or paraganglioma who require systemic anticancer therapy. Progenics also plans to explore potential pathways for additional AZEDRA indications in other multiple MIBG-avid tumor indications, including gastroenteropancreatic and other neuroendocrine tumors.

About International Isotopes Inc.

International Isotopes Inc. manufactures a full range of nuclear medicine calibration and reference standards and provides radiochemicals for clinical research and life sciences. The Company also produces bulk cobalt-60 and manufactures a variety of cobalt-60 products such as teletherapy sources and provides a wide range of radiological field services on a contract basis to clients.

For More Information Contact:

David Drewitz

Creative Options Communications

Investor and Public Relations

david@creativeoptionscommunications.com

www.creativeoptionsmarketing.com

Phone: 972-814-5723

For more information, please visit the Company web site: www.internationalisotopes.com

Source International Isotopes Inc.

Web Site: http://www.intisoid.com