As a response to recent cases of counterfeiting, Pfizer said that it would place new requirements on wholesalers and distributors that handle its products.

In a letter to the company’s wholesale customers, Pfizer said its products may be bought only from Pfizer or from wholesalers authorized by the company to handle those medications. Products may be sold only to pharmacies, hospitals, physicians or other distributors in the United States who are properly licensed by the states in which they operate, or to other Pfizer-authorized wholesalers. The restrictions take effect immediately and the company will refuse to do business with those who don’t comply.

“This is, first and foremost, a necessary step to protect patient safety,” said Pfizer chairman and CEO Hank McKinnell. “Pharmaceutical counterfeiting is a growing problem in the US and we must do everything we can to eliminate opportunities for counterfeiters to introduce fake products into the marketplace.”

Pfizer said its new initiative would help prevent distributors from purchasing its products on the secondary market, which has been a primary avenue for counterfeits to enter the U.S. distribution system. The company said it also will periodically audit purchases and sales of Pfizer medicines by its wholesalers and will require that they put in place a comprehensive plan to ensure the safety of the nation’s drug supply.

The company pointed out that this effort alone won’t solve the counterfeiting problem and said its customers are taking additional steps on their own to make the pharmaceutical distribution system more secure. Pfizer said it also is introducing new technology, improving product packaging and working very closely with law enforcement agencies and the FDA in a multi-faceted approach to combat counterfeiting.

“We’re in the healthcare business and people depend upon us,” McKinnell said. “We’re committed to do what it takes to further protect the health of the millions of patients who purchase and use our products every day.”