Most drug companies benefiting from the FDA’s “accelerated approval” process—a means of expediting approval of drugs intended for patients with life-threatening illness—have not conducted legally required post-marketing studies on their products, according to Rep. Edward J. Markey (D-MA).*
Created in 1992, the FDA’s accelerated approval process uses preliminary data indicating drug safety and efficacy to help bring drugs to the marketplace more quickly. This process greatly reduces the typical 10- to 15-year time period required to conceive, develop, and thoroughly test new drugs in animals and humans. In return for the enormous marketing advantages realized by drug makers, it was agreed that rigorous studies validating the preliminary data would continue in accordance with normal approval procedures.
Released on June 1, 2005, Rep. Markey’s report, Conspiracy of Silence: How the FDA Allows Drug Companies to Abuse the Accelerated Approval Process, reveals that at least 17 drug companies have not completed the FDA-required post-marketing studies. Of the 91 post-marketing studies promised since 1992, only 49 have been completed. Of the 42 pending studies, half have not even been initiated, though some of the approved drugs have been on the market for years; three are in progress but behind schedule; and only 18 are currently meeting scheduled milestones.
Although the FDA has the authority to withdraw drugs from the market in the absence of supporting data, it has not done so in any cases. The need for post-approval studies is well illustrated by AstraZeneca’s Iressa®, approved in May 2003 to treat non-small cell lung cancer. While preliminary data suggested that Iressa® would benefit 10% of patients, the FDA’s review of the mandated follow-up studies by AstraZeneca concluded that Iressa® provided no survival benefit and that patients taking it should discuss treatment alternatives with their physicians.
The FDA must enforce its requirements for post-marketing studies by drug makers in order to protect public safety.
—Linda M. Smith, RN
* Available at: http://www.house.gov/markey/Issues/iss_health_pr050601.pdf. Accessed June 15, 2005.
A diet rich in vitamin B6 may help prevent colorectal cancer, especially in women who consume alcohol, report researchers from Sweden and the United States.*
More than 61,000 women completed questionnaires providing long-term dietary information at the time of study enrollment (1987-1990) and again in 1997. Information was provided regarding family health history, smoking, and dietary intake of red meat, saturated fat, folate, and vitamin B6.
These findings suggest that vitamin B6 may help prevent colorectal cancer, particularly among women who drink alcohol. Vitamin B6 plays essential roles in DNA synthesis, repair, and methylation, and suboptimal B6 levels may contribute to colorectal carcinogenesis by impairing these processes. Moderate alcohol intake may exacerbate colorectal cancer risk by reducing intestinal vitamin B6 absorption and decreasing glutathione synthesis, thus making DNA more vulnerable to damage.
—Linda M. Smith, RN
* Larsson SC, Giovannucci E, Wolk A. Vitamin B6 intake, alcohol consumption, and colorectal cancer: a longitudinal population-based cohort of women. Gastroenterology. 2005 Jun;128(7):1830-7.
A compound found in green tea may work in a fashion similar to the anti-cancer drug methotrexate, according to researchers in Spain and England.*
While epidemiological studies have suggested that green tea prevents certain forms of cancer, its protective mechanism has been unknown. Recently, scientists found that epigallocatechin gallate (EGCG), a green tea polyphenol, inhibits the enzyme dihydrofolate reductase (DHFR), an established target for anti-cancer drugs.
Both healthy and cancerous cells require DHFR to manufacture DNA required for cell growth and replication. Certain cancer drugs such as methotrexate work by binding DHFR and blocking its activity. EGCG also binds to DHFR (though not as tightly as does methotrexate) and thus may produce less severe side effects than the drug.
Green tea’s EGCG content, which is about five times greater than that of black tea, may account for its long history of use as a cancer-preventive agent. EGCG exerts its anti-cancer effects at concentrations equivalent to those found in the serum and tissues of green tea drinkers.
Large amounts of green tea may decrease the effectiveness of folic acid, a protective agent against birth defects. These findings may explain why women who drink considerable amounts of green tea around the time of conception and early pregnancy experience an increased risk of having a child with a neural tube disorder. This finding provides another reason for why women who might become pregnant should supplement with folic acid.
—Elizabeth Wagner, ND
* Navarro-Peran E, Cabezas-Herrera J, Garcia-Canovas F, Durrant MC, Thorneley RN, Rodriguez-Lopez JN. The anti-folate activity of tea catechins. Cancer Res. 2005 Mar 15;65(6):2059-64.
Melatonin helps ameliorate abdominal pain associated with irritable bowel syndrome (IBS), report researchers at the National University Hospital in Singapore.1
Best known as a sleep-promoting neurohormone derived from the pineal gland, melatonin is also synthesized in the gastrointestinal tract, where concentrations may be as much as 100 times those in the blood.2 In the gastrointestinal tract, melatonin supports stomach lining repair, prevents ulcerations, and increases microcirculation; researchers have speculated that melatonin may have promise in managing gastrointestinal tract disorders.2
In the recent Singapore study, 40 subjects with both IBS and sleep disturbances were randomly assigned to one of two groups. The study group received 3 mg of melatonin at bedtime for two weeks, while the control group received placebo. Before beginning the study and upon its completion, each subject completed four questionnaires to assess bowel symptoms, psychological status, sleep quality, and level of daytime sleepiness. Each subject also underwent rectal pressure determination and a recorded overnight sleep study.1
After just two weeks of supplementation, the melatonin-supplemented subjects experienced 58% less abdominal pain, compared to 18% in the placebo group. Such pain indicates gastrointestinal tract hypersensitivity and is the most frequent complaint of IBS sufferers. Other parameters of bowel dysfunction improved in the melatonin group, though this difference was not statistically significant. The two groups reported no differences regarding sleep parameters.1 Melatonin thus shows promise in alleviating the gastrointestinal discomfort associated with IBS.
—Linda M. Smith, RN
1. Song GH, Leng PH, Gwee KA, Moochhala SM, Ho KY. Melatonin improves abdominal pain in irritable bowel syndrome patients who have sleep disturbances: a randomized double blind placebo controlled study. Gut. 2005 May 24; [epub ahead of print]
2. Bubenik GA. Gastrointestinal melatonin: localization, function, and clinical relevance. Dig Dis Sci. 2002 Oct;47(10):2336-48