After oral administration many physiological parameters play an important role in drug dissolution. And one of them is definitely volume of the media in the gastrointestinal tract, because it defines the amount of liquid available for drug dissolution. According to FDA and EMA a medication administered under fasted conditions should be taken with 240 mL or at least 150 mL of water. To establish whether this amount of water influences drug dissolution, we have simulated paracetamol release under simulation of different gastric emptying profiles in a flow-through system.
The flow-through system with glass beads consisted of a working beaker and two peristaltic pumps. One was used to pump 0,01 M HCl with a constant rate of 2 mL/min into the beaker, which simulated excretion of gastric acid, and the other one was used to pump the contents out of the beaker. Gastric emptying profiles after intake of 240 mL of water that were used as a basis for simulating gastric empyting in the flow-through system were obtained from a scientific article, and were modified just slightly to perform the experiments with the use of available equipment. We compared paracetamol release following 3 different gastric emptying profiles – fast, slow and average. Results obtained with these 3 emptying profiles were compared to dissolution of paracetamol in 40 mL of 0,01 M HCl, when both peristaltic pumps were working at the rate 2 mL/min, which simulated gastric conditions in the fasted state.
We tested 12 formulations with different drug release kinetics. Most of them only differentiated in amount and/or type of polymer used. We have noticed the amount and rate of drug release were influenced by simulated gastric emptying. The biggest difference between drug dissolutions profiles were noticed when testing paracetamol release with constant flow rate of 2 mL/min and under different emptying profiles in formulations with the fastest drug release kinetics. We have also found the biggest differences when comparing paracetamol dissolution under constant flow rate of 2 mL/min and simulated fast emptying profiles, and in contrast, the smallest differences in dissolution profiles when comparing with simulated slow emptying profiles. The results therefore hint the water ingested with medication could impact paracetamol dissolution, but further investigation, especially with other, less-soluble active pharmaceutical ingredients, should be conducted before coming to any conclusions.
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