Saturday August 23, 2008 (foodconsumer.org) -- The Food and Drug Administration on Friday Aug. 22 announced its approval of Nplate (romiplostim) manufactured by Amgen, Inc. of Thousand Oaks, California as a bone marrow stimulator to treat immune-related low platelet counts.

Nplate is the first of its kind ever approved by the FDA to stimulate the bone marrow to produce platelets that patients with a rare blood disorder need to prevent serious bleeding due to low counts of platelets.

The blood disorder of concern is known as chronic immune thrombocytopenic purpura or ITP, which develops in adults resulting in a low number of platelets. The drug helps with clotting and prevents bleeding, according to the FDA.

In patients with chronic ITP, the immune system destroys platelets and the bone marrow is not able to compensate the loss, leading to increased risk of serious bleeding.  An estimated 140,000 people in the U.S. suffer chronic ITP.

"This product is important in that it offers a new approach to the treatment of patients with an uncommon blood disorder who are often very ill," said Janet Woodcock, M.D., director, Center for Drug Evaluation and Research, FDA.

The treatments available currently include corticosteroids and immunoglobulin. Splenectomy, a procedure to remove the spleen, may also help some patients.

But Nplate is approved only for chronic ITP patients who do not respond to current treatments.

The FDA approval was based on two clinical trials of about 125 patients who had received at least one treatment prior to the trials with one study on patients who still had their spleen and another on patients who had had their spleen removed.

Results from six months of treatment showed patients who received Nplate had significantly higher counts of platelets and maintained higher counts than those who did not receive the medication.

The efficacy was good mostly among those who still kept their spleen.   Of those who underwent a splenectomy, only one experienced maintained an increased in platelet counts.

However, higher platelets counts needed to be maintained by taking Nplate.   Once the treatment was stopped, platelet counts dropped even below the beginning counts. Another side effect is that the drug caused fibrous deposits in the bone marrow and blood clots due to excessive increases in platelets.

Nplate also predisposed some patients with a blood disorder known as myelodysplasia to leukemia, a blood cancer.   A study showed of 44 patients with myelodysplasia, four developed leukemia. But the FDA said further research is needed to determine whether it is Nplate that causes increased risk of leukemia.

Because of these adverse effects, Nplate is only approved for patients who have chronic ITP but do not respond sufficiently to current treatments.

Herbchina2000.com reported that an herbal remedy based on Chinese herbs has been proved to be very successful in treating Primary thrombocytopenic purpura. The source cites a study saying that of 52 cases, 39 patients who were treated with the remedy were recovering and free of symptoms while another 11 improved their conditions.   Another study also showed the remedy is also equally effective at treating Secondary thrombocytopenic purpura. No side effects were observed.

Analysts expect the sales from about 60,000 U.S. patients with chronic ITP to be at anywhere between $66 and $117 million in 2009, Reuters reported.   Also Amgen will face competition from GlaxoSmithKline which also expects to get FDA approval for its Promacta or eltrombopag in September.