Formulation of a charcoal suspension for intratumoral injection. Study of galenical excipients

To tattoo human breast cancer prior to chemotherapy, radiotherapy, or surge ry, thus allowing a better localization of the remaining tumor by the surge on, we developed a formulation containing 10% charcoal suspended in water f or parenteral preparations. The present study concerns a new step in the de velopment of the charcoal suspension. We sought to determine whether the ad dition of various excipients could improve the formulation properties and a ffect the labeling of tumor by the suspension. We have tested surfactants ( egg lecithin, polysorbate 80 Cremophor EL, and Pluronic F68), isotonisants (sugars such as glucose and mannitol), polysaccharides (dextrans 20 and 40) , and Cabosil, a pyrogenated silica. Except for glucose and mannitol, which were added at a 5% concentration, the other excipients were added at a 0.1 % concentration. they were dissolved in water for parenteral injection and sterilized at 120 degrees C for 20 min. We then measured diffusion in vivo in mammary tumor. In vivo, when injected intratumorally in mice, a gl eater diffusion of charcoal particles was noted within the tumor (in the case of egg lecithin, polysorbate 80, dextran 20 and 40, and glucose) and sometime s in some organs (e.g., Cremophor EL and mannitol). Pluronic F68 slightly i mproved the stability of the suspension and did not lead to marked diffusio n at the injection site, but it showed slight toxicity and cannot be used i n the formulation. We concluded that the best formulation was an aqueous 10 % micronized peat charcoal suspension.