In vivo comparison of enteric capsule shells composed of different HPMCAS grades after simultaneous intake by dual MRI labeling and pharmacokinetics

C-labeled caffeine to act as distinguishable pharmacokinetic markers. Different amounts of iron oxide led to distinguishable artifacts in TRUFI sequences. Manganese gluconate led to a bright cloud in VIBE sequences when test capsule disintegrated, allowing for very sensitive detection of opening and interesting visualization of small intestinal spreading after release. Reference HPMCAS grade H capsules mainly disintegrated in ileum, while test capsules disintegrated in more proximal regions of small intestine or in terms of HPMCAS grade L even in stomach already. Utilization of an internal standard with dual labeling by dosing test and reference simultaneously was a relevant improvement in study design. HPMCAS grade M is a robust alternative to HPMCAS grade H if faster and more proximal disintegration is desirable.