Failure of labelling of anti-granulocyte antibody

Alguns aspectos sobre geradores e radiofármacos de tecnécio-99m e seus controles de qualidade

Radiofármacos marcados com tecnécio-99m são os principais agentes para diagnósticos utilizados nas clínicas de medicina nuclear, em função de uma série de características físicas do radionuclídeo e pela praticidade dos radiofármacos serem preparados no local de uso, por meio de uma reação de complexação entre um agente complexante (fármaco) e o tecnécio-99m. Entretanto, durante esta reação podem ser geradas algumas impurezas que proporcionam a formação de produtos com baixa qualidade ou com características diferentes das desejadas. No presente trabalho serão apresentados alguns dos fatores que podem interferir na qualidade dos radiofármacos e os controles que podem ser utilizados para garantir sua qualidade.

Radiochemical purity of routinely prepared 99Tcm radiopharmaceuticals: a retrospective study

Radiochemical purity is an important quality parameter for radiopharmaceuticals. In this study, the radiochemical purity of 2090 samples out of 7000 routine preparations of 20 different 99Tcm radiopharmaceuticals was tested using standard methods over a period of more than 7 years. The mean radiochemical purity was 96.92% (standard deviation = 6.71%). Seventy-four preparations failed to meet radiochemical purity limits; that is, 3.54% of all preparations tested or 1.06% of all preparations in the observation period. The reasons for substandard preparations were mainly related to laboratory-specific conditions. The introduction of a dedicated quality control protocol allowed the elimination of many sources of labelling failures and could reduce the number of administered preparations with an insufficient radiochemical purity. We stress the need for quality control in the preparation of radiopharmaceuticals and provide original radiochemical purity values of routinely prepared 99Tcm radiopharmaceuticals.

Determination of Sn(II) in technetium cold kits by voltammetry at the hanging mercury drop electrode (HMDE) and relevant radiopharmaceutical applications

A novel approach for the determination of the stannous content in cold kits for labelling with 99mTc is described. The method is based on differential pulse polarography on the hanging mercury drop electrode in a methanol/water/perchloric acid mixture and is easy to perform. Examples for the determination of tin(II) in fractionated technetium cold kits are shown. The stability of tin(II) in solution was mainly dependent on the storage temperature and the kit composition. The low stability of stannous ions under certain conditions was shown to be the main reason for low radiochemical purity. Limits and dangers of fractionating kits are discussed and related to content and instability of tin(II).

Radiopharmaceutical-related pitfalls and artifacts

The primary goal of this review article is to increase the reader's knowledge and understanding of problems associated with the radiopharmaceuticals commonly used in daily practice. To achieve this objective, problems related to the commonly used radiopharmaceuticals are divided into pitfalls and artifacts related to radiopharmaceutical preparation (technetium-99m [99mTc]-labeled and non-99mTc-labeled radiopharmaceutical) and those related to radiopharmaceutical administration. For the radiopharmaceutical formulation-associated pitfalls and artifacts, problems are discussed in terms of factor categories, such as factors associated with radionuclides, factors associated with components, factors associated with preparation procedures, and miscellaneous factors. As for the pitfalls and artifacts caused by radiopharmaceutical administration, these problems are categorized into errors associated with administration technique and nontechnical errors. Clinical manifestations (ie, appearance upon imaging) from the numerous literature-based examples are presented. The effect of the causative factors and the reason each factor can result in radiopharmaceutical preparation and administration problems are discussed. In addition, the possible preventive actions are presented for each group. However, the cause of some pharmaceutical related problems may not be easily recognized, and thus it is difficult to develop preventive and/or corrective plans for these cases.