[Radioiodine testing in clinical routine: Status in Germany 2021]. / Statuserfassung des Radiojodtests im klinischen Alltag in Deutschland 2021.

INTRODUCTION AND AIM: According to the German guideline on Radiation Protection in Medicine, the activity to be applied for radioiodine therapy of benign thyroid diseases is determined for each patient by means of the radioiodine test (RJT). The aim of this study is to record the different parameters of the RJT. MATERIAL AND METHODS: A web-based questionnaire was sent to all nuclear medicine departments in Germany via the DGN office. Parameters regarding tracer and activity, type of probe measurement, number and timing of measurements, use of fixed effective half-lives (eHWZ), calculation model and organ doses were requested. An assessment of continuous measurement of the thyroid iodine uptake over seven days by a wearable probe system was also requested. RESULTS: 38 of 94 facilities responded to the questionnaire. Major differences in RJT implementation were found concerning the parameters number and timing of measurements, probe-patient distance, use of fixed disease-specific eHWZ, and intended organ dose. Despite the DGN Guideline and DIN 6861-1, 74% of the facilities still use the simplified Marinelli formula from the DGN Recommendation of 1998. Only 8% have switched to the two-compartment model. 84% of the institutions expect that a wearable probe system could improve the calculation of the radioiodine activity necessary for treatment, but only 57% expect an improvement in the therapeutic outcome. CONCLUSIONS: The methodology of RJT in Germany is heterogeneous and still based on the "Marinelli method" in most institutions despite new guidelines and recommendations. A continuous measurement of the iodine kinetics using a wearable probe system could result in further improving the radioiodine test in addition to the newer calculation algorithms.

Solvent-Containing Closure Material Can Be Used to Prevent Follicular Penetration of Caffeine and Fluorescein Sodium Salt on Porcine Ear Skin.

AIM: The skin represents a drug delivery portal. The establishment of a skin model capable of distinguishing between the follicular and intercellular penetration pathways remains a challenge. The study described herein was aimed at showing the influence of two nail varnishes as closure material and four application techniques to spread the active pharmaceutical ingredient (API) on a successful follicular closure without inducing penetration-enhancing effects. MATERIALS AND METHODS: For all experiments, ex vivo porcine ear skin was used. In study design A, a standard and a solvent-free nail varnish were compared. It was tested whether the different application techniques (spreading with pipette, careful finger massage, 5-Hz finger massage, 5-Hz automatic massage) potentially destroy an intact follicular closure. Laser scanning microscopy imaging was used to measure if the model drug (fluorescein sodium salt) penetrated into the hair follicles. Study design B investigated how the penetration is affected when applying standard nail varnish containing solvents to skin. It was tested if the varnish blocks the API (caffeine) on completely covered areas and if adjacent areas show increased penetration. Furthermore, lateral diffusion of the API was investigated. After 20 h, the skin layers were separated by tape stripping and heat separation. The tissue samples were homogenized. Caffeine was quantified by chromatography. RESULTS: In study design A, the standard nail varnish showed a secure follicular closure, while the solvent-free nail varnish was not able to prevent follicular penetration. Moreover, rapid application techniques were found to destroy an intact follicular closure. Only the two most gentle application techniques kept the follicular closing intact. In study design B, no caffeine was detected in both skin areas that were completely covered. Since no significant difference in caffeine penetration between the two uncovered groups was found, any influence of the applied closure material on adjacent areas was excluded. CONCLUSION: This study clearly demonstrates that a standard nail varnish in combination with a gentle application technique of the API provides a secure follicular closure. The presented study only investigated the closure for the substances caffeine and fluorescein sodium salt. The results might not be transferable to all kinds of APIs.