The US Food and Drug Administration (FDA) has drafted a current Good Manufacturing Practice (cGMP) regulation for the production of drugs used in positron emission tomography (PET), a diagnostic tool.
The regulation aims to establish minimum standards for the production and testing of PET drug products, taking into account some of the particular properties of these agents which are not adequately covered in existing cGMP regulations for other drugs.
PET is a medical diagnostic tool in which a radioactive drug is administered to a patient, most commonly by intravenous injection, and the distribution and uptake of the radioactive drug to various bodily organs is imaged using a special camera or scanner. The image helps physicians diagnose diseases such as cancer and heart disease. PET images show biochemical changes of an organ or tissue in the human body, unlike X-ray, CT, or MRI images which show only bodily structures.
One PET drug, known as fludeoxyglucose or [F18] FDG, has been shown to be useful in identifying active tumours, for monitoring the progression or regression of malignancies, and for monitoring the effectiveness of therapeutic interventions. PET drugs have a short half-life, that is, they decay with time and must be used within hours or minutes after production. This characteristic affects how they are produced and as a result, some of the cGMP requirements for traditional pharmaceuticals are not necessary or appropriate for the production of PET drugs, said the FDA.
Originally, PET drug products tended to be produced in academic institutions. Increasingly, however, production of PET drugs has become more commercialised and PET drugs are being reimbursed by private insurance plans in the US, according to the agency.
The FDA Modernisation Act of 1997 suspended the requirement that PET drugs be marketed under approved applications until 2 years after FDA established approval procedures and cGMP requirements for PET drugs.
FDA is publishing the proposed cGMPs for a 90-day comment period, and will then prepare a final rule. Two years after that final rule takes effect, PET producers will be required to submit new drug applications before marketing a PET drug. Although not yet required to submit applications for marketing, recently, two PET centers voluntarily submitted and obtained approval to market FDG.