Related Experiment Video
Updated: Aug 8, 2026

Models and Methods to Evaluate Transport of Drug Delivery Systems Across Cellular Barriers
Published on: October 18, 2013
In vivo evaluation of a novel pH- and time-based multiunit colonic drug delivery system
C Bott1, M W Rudolph, A R J Schneider
12nd Department of Medicine, JW Goethe University, Frankfurt/Main, Germany.
Background:
Targeted drug delivery to the colon is important for topical treatment of inflammatory bowel diseases. Established targeting systems predominantly focus on either pH- or time-dependent release, or bacterial degradation.
Aim:
To perform a three-phase, crossover design trial evaluating a novel combined pH- and time-based multiunit delivery system.
Methods:
Twelve healthy male volunteers each received 200 mg of caffeine as either uncoated immediate release tablets, coated pellets with pH-dependent rapid release (EUDRAGIT FS 30D), and pellets with pH- and time-based release (inner layer EUDRAGIT RL/RS 30D; outer layer EUDRAGIT FS 30D). Orocecal transit time was measured using lactose-[13C]ureide. Serum concentrations of caffeine were measured by high-performance liquid chromatography.
Results:
In contrast to the uncoated tablet, both coated systems reached the ileocecal region almost at the same time (3.19 +/- 0.71 and 3.33 +/- 0.81 h). Serum caffeine profiles were significantly prolonged for the pH and time delivery system compared with the pH-only based system (median tmax 12.0 vs. 5.5 h; P < 0.001). This was further reflected by a lower Cmax value and a lower area under the curve within 24 h after application.
Conclusion:
Compared with the conventional delivery systems, drug release from the new dosage form may offer a new dimension for the oral treatment of mid to distal ulcerative colitis.
More Related Videos
Related Concept Videos
Methods for Studying Drug Absorption: In vitro
The diffusion cell method uses a two-compartment cell, including a donor compartment with the drug solution, which simulates the environment where the drug is applied, and a receptor compartment with a buffer solution, which simulates the environment...
Methods for Studying Drug Absorption: In situ
The Doluisio method involves perfusing a prepared segment of a rat's small intestine with a solution of radiolabeled drug and a non-absorbable marker. This helps to differentiate between absorbed and non-absorbed drug concentrations. The intestinal segment is connected at both ends using tubing and syringes,...
One-Compartment Open Model for IV Bolus Administration: Estimation of Elimination Rate Constant, Half-Life and Volume of Distribution
In Vitro Drug Dissolution: Alternative Methods
Drug Product Performance: In Vitro–In Vivo Correlation
Modified-Release Drug Delivery Systems: Bioavailability

