In Vitro Simulation of Tissue Back-Pressure for Pen Injectors and Auto-Injectors

Abstract

Purpose: The aim of this project was to show that tissue back-pressure can be measured in vitro using a simple pneumatic model. Methods:A thorough literature study revealed four relevant papers all describing in vivo studies. One of these studies where the subcutaneous tissue back-pressure was determined in 11 patients was used as a reference for the present work. A pneumatic model capable of simulating the back-pressure and the diffusion of drug during subcutaneous injection was developed. The in vitro model was tested using the same type of pen injector as used in the reference study.Results: Comparison of the results revealed that the measured pressure in the in vitro experiments were similar to the subcutaneous tissue back-pressure measured in vivo. G30 0.3 x 8.0 mm and G32 0.23/0.25 x 4.0 mm needles were used for the in vitro experiments, whereas a G31 0.25 x 6.0 mm needle was used for the in vivo experiments. This is one possible explanation of approximately 30 µL/s higher flow rates for the in vitro experiments compared to the in vivo experiment. Conclusion:The low-complexity model allows repeated measurements, and provides a stable data output paving the way for measuring subcutaneous back-pressure in vitro.

Oil extraction through hydraulic pressing from Cambodian soybean seeds and analysis of its physicochemical quality

“…Oil quality with a peroxide value below 10 meq/kg is considered fresh oil, but when the peroxide value is between 20 and 40 meq/kg, the oil becomes rancid (Low & Ng, 1987). The iodine value was 126.01 ± 1.68 g I2/g oil since the higher the iodine value, the greater the number of double bonds (Yildiz, Alfeen, & Yildiz, 2019). Moreover, the acid value was 0.67 ± 0.00 mg KOH/g oil, while the decomposition of the acid value is accelerated by heat and light (Kim & Siang, 1987).…”