Fig. 4

Resistance of wax-coated capsules to simulated GI fluids (n = 3). To demonstrate the high resistance of the wax coating to enzymatic activity and low pH, the wax-coated capsules were exposed to simulated GI fluids at 37 °C. Visual control after 2 h incubation in simulated pepsin-containing gastric fluid USP at pH 1.2 (a) and subsequent 24 h in pancreatin-containing simulated intestinal fluid USP at pH 6.8 (b) revealed no apparent morphological changes (c). Moreover, no significant change in mass was observed (p = 0.400, mean ± standard deviation, d). GI: Gastrointestinal; USP: United States Pharmacopoeia