Preparation and Quality Control of Some Formulated Anticancer Radiopharmaceuticals

For the majority of solid tumors, hypoxia develops because of the inability of the vascular system to supply the growing tumor mass with adequate amounts of oxygen. Over the last decade, it has become evident that hypoxia changes the patterns of gene expression in several ways that alters the malignant potential of tumors, leading to more aggressive survival traits. Tumor hypoxia represents a significant challenge to the curability of human tumors leading to treatment resistance and enhanced tumor progression. This has lead to the development of assays for the detection of hypoxia in patients in order to predict outcome and identify patients with a worse prognosis and/or patients that would benefit from appropriate treatments. A variety of invasive and noninvasive approaches have been developed to measure tumor oxygenation. Example of noninvasive molecular imaging modalities is nuclear medicine which is a branch or specialty of medicine and medical imaging that uses radionuclides and relies on the process of radioactive decay in the diagnosis and treatment of disease. For diagnostic purposes nuclear medicine imaging techniques are performed by means of administering pharmaceuticals that are labelled with radionuclides (gamma emitters), so that they are preferentially accumulated in the organs of interest.Thus, noninvasive imaging methods for identification and quantitation of tumor hypoxia with positron emission tomography (PET) and single-photon emission computed tomography (SPECT) have received serious attention to predict and monitor treatment response. SPECT is a technique widely used in nuclear medicine for the imaging of many organs including the skeleton and heart, as well as for whole body imaging for the detection of tumors. SPECT uses single photon emitting radionuclides ligated with hypoxia specific compounds that generate a signal from the hypoxic areas of tumors. Radiopharmaceuticals are preparation of adequately constant composition, radiochemical, radionucledic purity and uniformity of physiological action for use in nuclear medicine as diagnostic aid or therapeutic agents. Due to the favourable physical properties of 99mTc for gamma camera imaging, it is today the most widely used radionuclide in diagnostic nuclear medicine. The short half-life of 6.02 h (it is short enough to save the patient from high radiation dose and long enough to carry out labelling and scintigraphic measurements) and the nearly pure 140 KeV γ-emission reasonable for SPECT and very low abundance emission make it suitable for imaging processes. Technetium-99m is readily available in a sterile, pyrogen free, and no-carrier added state from ⁹⁹Mo/^99mTc generators