An important drug that serves as the backbone of treatment for most childhood cancers, has become increasingly rare, and doctors are warning that they may soon be forced to consider rationing doses(定量供应剂量)．
There have been longterm shortages of certain drugs and medical supplies in the United States for years, but doctors say the loss of this medication, vincristine(长春新碱) is leading to lots of problems, as there is no appropriate substitute. "This is truly a sad situation," said Dr. Yoram Unguru, a doctor at the Herman and Walter Samuelson Children's Hospital at Sinai in Baltimore. "Vincristine is our water. It's our bread and butter. I can't think of a treatment for childhood cancer that doesn't use vincristine." Shortages of the drug will likely affect children throughout the country, he said, forcing doctors to make difficult decisions. "There is no substitution for vincristine that can be recommended," Dr. Unguru said. "You either have to skip a dose or give a lower dose or beg or borrow."
Vincristine is one of the drugs used to manage leukemia, the most common childhood cancer. The Children's Oncology Group, a group of researchers at hospitals and cancer centers, has made recommendations for changing clinical trial treatment rules involving vincristine, including checking the hospital's supply before trial enrollment, and considering using half the dose if the full amount is not available.
"We are all disappointed," said Dr. Michael Link, a doctor at the Stanford University School of Medicine. Without vincristine, many children with acute lymphoblastic leukemia will still be cured, "but this is a difficult disease to treat in general, and with one hand tied behind your back, it makes it much more difficult，"Dr. Link said.
Until earlier this year, there were two suppliers of vincristine: Pfizer and Teva. In July, Teva made a "business decision to discontinue the drug," according to the Food and Drug Administration (FDA). Since then, Pfizer has been the only supplier, and the company lately has been experiencing troubles with production. "Pfizer has experienced a delay, and we are working closely with them and exploring all ways to make sure this important cancer drug is available for the patients who need it," the FDA said. Jessica Smith from Pfizer said the company would speed up additional shipments of the drug over the next few weeks in an effort to make up for Teva's withdrawal from the market.
