The U.S. Food and Drug Administration has approved an application for the first generic of Daraprim (pyrimethamine) tablets for the treatment of toxoplasmosis (an infection caused by the parasite Toxoplasma gondii) when used with a sulfonamide (a group of medicines used to treat bacterial infections).
Toxoplasmosis is an infection caused by a single-celled parasite called Toxoplasma gondii that, when severe, can cause damage to the brain, eyes or other organs. A Toxoplasma infection can occur, among other ways, by eating undercooked, contaminated meat or shellfish; drinking water contaminated with Toxoplasma; or by accidental swallowing of the parasite through contact with cat feces that contain Toxoplasma. It is considered to be the leading cause of death attributed to foodborne illness in the United States.
Severe toxoplasmosis is more likely in pregnant women and individuals who have weak immune systems, such as those with HIV or AIDS, those taking certain types of chemotherapy and those who have recently received an organ transplant. However, occasionally even persons with healthy immune systems may experience eye damage from toxoplasmosis.
One area of focus under the action plan is improving the efficiency of the generic drug development, review and approval process, as well as closing loopholes that allow brand-name drug companies to delay the generic competition. As part of these important efforts, the FDA maintains a list of off-patent, off-exclusivity drug products without an approved generic to improve transparency and encourage the development and submission of applications for drugs with limited competition. Pyrimethamine is included on this list. The FDA also prioritizes the review of submissions for generic drugs for which there are fewer than three approved generic versions for the reference listed drug (RLD) and for which there are no blocking patents or exclusivities on the RLD.
Additionally, certain “gaming” tactics have been used at times to delay generic competition. One example is when brand-name drug manufacturers attempt to prevent potential generic applicants from obtaining samples of certain medicines necessary to support approval of a generic drug application. To improve transparency about this issue, the FDA posted a list identifying all drugs for which the FDA has received an inquiry related to limited distribution of the reference drug from a prospective generic applicant. Daraprim is on this list.
Pyrimethamine should not be used in patients with known hypersensitivity to pyrimethamine or with documented megaloblastic anemia due to folate (a naturally-occurring B vitamin) deficiency. Women who are taking pyrimethamine should not become pregnant. Patients should keep pyrimethamine out of the reach of children.
A small “starting” dose for toxoplasmosis is recommended in patients with convulsive disorders to avoid the potential nervous system toxicity of pyrimethamine. Pyrimethamine should be used with caution in patients with impaired renal (kidney) or hepatic (liver) function or in patients with possible folate deficiency, such as individuals with malabsorption syndrome, alcoholism or pregnancy, and those receiving therapy, such as phenytoin (an anti-epileptic drug), affecting folate levels.
