In vivo evaluation of a novel pH- and time-based multiunit colonic drug delivery system.

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.

A new 5-aminosalicylic acid multi-unit dosage form for the therapy of ulcerative colitis.

The aim of the present study was to develop a multi-unit dosage form containing 5-aminosalicylic acid (5-ASA) for the treatment of ulcerative colitis (UC), optimised on the basis of recent studies indicating that UC patients have higher intestinal pH than was previously thought to be the case. Pellets with a drug content of 77.4% were prepared by a granulation and spheronization process and then coated with a new pH sensitive poly(meth)acrylate copolymer (Eudragit((R)) FS 30D) to achieve site specific drug release close to the ileocecal valve. Dissolution tests were carried out in a paddle dissolution apparatus in media simulating pH conditions at various locations in the gastrointestinal tract. The pellets released rapidly at pH values above 7.5. Between 6.8 and 7.2 drug release was found to be zero order, while at pH 6.5 and below no release occurred. In a biorelevant medium which simulates the fasting proximal small intestine fluid it was shown that neither surfactants (sodium taurocholate and lecithin) nor changes in ionic strength trigger drug release. Compared to 5-ASA pellets coated with the well established Eudragit((R)) S, and to currently marketed products licensed for the treatment of UC, the multi-unit dosage form coated with the new polymer exhibited an in vitro dissolution profile more appropriate to the pH profile of the ileum and the colon observed in UC patients.