Introduction The region of unbuffered acidity on top of the gastric contents after a meal, known as the post-prandial acid pocket,1is a chief aetiological factor responsible for the frequently experienced post-prandial reflux.
We previously developed an in vitromodel of the post-prandial acid pocket adhering to the physiological characteristics described in the clinical literature.2Here we further improve this in vitromodel to simulate the occurrence of reflux events and also evaluate some anti-reflux products.
Method A standard refluxogenic meal (McDonalds double sausage and egg McMuffin + black coffee) was blended with 40 ml 0.01 M HCl and transferred to the model stomach within a sealed water chamber. An acid pocket layer of 0.1 M HCl was applied to meet the established clinically measured parameters (70 ml and 2.5 cm depth). A reflux event was simulated by applying air pressure into the water chamber rapidly and the refluxate was captured in a syringe through the modelled lower oesophageal sphincter. The model was validated with two alginate-based anti-reflux products [UK manufactured Gaviscon Double Action (GDA) and USA manufactured Gaviscon Extra Strength (GES)].
Results Application of 50 ml of air to the in vitropost-prandial acid pocket model resulted in refluxate volume of 10 ml (SD 1.7 ml) which is a representative refluxate volume.3
GDA suppressed reflux in the model in a dose dependent manner with 20 ml maximum GDA dose completely supressing 5 sequential reflux events. 10 ml GDA dose let through 2.7 ml of the reflux (mean of 5 events) and 2.5ml GDA dose let through 5.9 ml of the reflux (mean of 5 events). 20 ml maximum dose of GES did not supress reflux and 7.0 ml of the reflux was let through at maximum dose (mean of 5 events).
Conclusion This in vitromodel is representative of a fed stomach via introduction of a classic refluxogenic meal. The post-prandial acid pocket that is modelled represents that described in clinical studies and the model takes into account the pressure changes during a reflux event.
Alginate raft forming anti-reflux products GDA and GES were chosen to validate the model and GDA was able to suppress reflux events in a dose dependent manner with maximum dose (20 ml) totally supressing all reflux events. In contrast GES that does not form a coherent buoyant raft4was a poor reflux suppressant.
This in vitromodel of reflux of the post-prandial acid pocket has potential to screen and evaluate test products without the need of clinical studies.
Disclosure of interest None Declared.
Fletcher, et al. Gastroenterology 2001;121:775–783
Fisher, et al. UEG Journal2014;2(Suppl 1):A578
Sifrim Gut 2005;54:175–178
Hampson, et al. Int J Pharm. 2005;294:137–147