The consumer advocacy group Public Citizen says that when the Food and Drug Administration (FDA) gave approval for Hetlioz (tasimelteon), a drug to treat non-24 sleep-wake disorder, the agency may mistakenly omitted language from the label indicating that the drug is intended only for patients who are blind, thereby possibly expanding the drug’s use to patients for whom it was not approved.
The FDA issued a new approval letter when it became aware of the mistake, but the second letter did not correct the error. Instead, the FDA changed the description of approved use to match the incorrect labeling, according to the Wall Street Journal.
Public Citizen has petitioned the FDA to correct the label to indicate that the drug is intended only for patients with non-24 sleep-wake disorder who are totally blind, a population of approximately 100,000, according to the drug’s manufacturer. Public Citizen is concerned that existing labeling may encourage use of Hetlioz in people who are not blind and have some other type of sleep disorder, according to the WSJ Pharmalot blog.
In its letter to the FDA, Public Citizen asks that Vanda Pharmaceuticals be required to conduct a large “adequately powered” postmarket clinical trial in totally blind subjects “to obtain more robust safety data in this patient population.” In the preapproval safety database, Public Citizen says, just 139 subjects received tasimelteon for more than 26 weeks and only 183 totally blind subjects with non-24 sleep-wake disorder received the drug at all for any length of time. Non-24-hour sleep-wake disorder is a chronic condition and tasimelteon would be taken for years. Therefore, trial subjects should take tasimelteon for at least two years in order for Vanda to gather more information on the long-term risks, Public Citizen explains.
Public Citizen argues the FDA violated legal standards for drug approval because clinical data submitted by Vanda did not include studies of people who have non-24 sleep-wake disorder but are not blind. Vanda applied to market the drug only to people with the disorder and who are blind, but the current labeling would permit its use by people are not blind. Public Citizen maintains there is no evidence the drug is safe and effective for people who have the disorder and are not blind. Further, Public Citizen says the product labeling should include data about toxic effects that was seen in animal studies, according to the WSJ. Public Citizen asks that the “carcinogenesis,” “mutagenesis,” and “pregnancy” sections of the prescribing information be updated to indicate risks missing from the current label.
An FDA spokesperson told Pharmalot that the agency will review Public Citizen’s petition and respond directly to the organization. “The actions taken by the FDA in response to the original mistake in approving [the] erroneous label are unacceptable and deeply disturbing,” says Dr. Michael Carome, who heads Public Citizen’s Health Research Group. Carome says the FDA “has allowed a potentially dangerous medication to be given to people for whom there is a lack of substantial evidence that it is safe and effective.”