Time and pH dependent colon specific, pulsatile delivery of theophylline for nocturnal asthma

Development of colon targeted multiparticulate pulsatile drug delivery system for treating nocturnal asthma

“…The test was carried out in a USP dissolution type I assembly (Electrolab, TDT-08L, India) at a rotation speed of 100 rpm in 900 ml medium at 37°C in media with pH 1.2 (HCl 0.1 N), pH 7.4 and pH 6.8 (phosphate buffer) for 2 h, 3 h, and the remaining 7 h, respectively. The 5 ml aliquots of the dissolution fluid were removed at specified time intervals and assayed for the amount of TP by spectrophotometer (Shimadzu, UV 1700, Japan) at wavelength 271 nm for all three media (Zahirul, 1999;Gang et al, 2004;Akhgari et al, 2005;2006;Mastiholimath et al, 2007;Siepmann et al, 2008;). …”

“…It was expected to be a reasonably hydrophobic layer with drug release being controlled by the thickness of the layer. In order to simulate the pH changes along the GI tract, three dissolution media with pH 1.2, 7.4, and 6.8 were sequentially used, referred to as sequential pH change method (Gang et al, 2004;Mastiholimath et al, 2007). At pH 1.2 (simulating stomach) none of the formulations released their drug content up to 2 h. In order to determine the levels of factors which yield optimum dissolution responses, mathematical relationships were generated between the dependent and independent variables.…”

Formulation Approach for Nicorandil Pulsatile Release Tablet

“…Where h is the penetration depth of the liquid, t is the time from contact of the liquid and powder, r is the mean radius of the capillary tube in the powder layer, g L is the surface tension of the liquid, q is the contact angle and h is the viscosity of the liquid. 8) (1) This equation can be converted into Eq. 2.…”

“…These dosage forms were intended for drug release in a specific region of the gastrointestinal tract or time dependent release for chronotherapeutics. [1][2][3][4][5] From the technological point of view, most of the dosage forms can be classified as a single-unit type or multiple-unit type. The multiple-unit type is applied when strict time control for release is necessary and rapid release rate is less important.…”

A novel pulsed drug-delivery system: polyelectrolyte layer-by-layer coating of chitosan–alginate microgels

“…For instance, a pulsed drug delivery system can release drug synchronizing with the body's circadian rhythm or disease states to produce maximal therapeutic benefit and minimal side effects. [1][2][3][4][5][6][7][8][9][10] At the same time, most pulsed drug-delivery systems need external triggers for drug release. These external triggers include changes in the physiological environment (eg, glucose levels, hydroxyl radicals, and hyaluronidase at inflammatory sites) or external stimuli (eg, magnetism, ultrasound, temperature changes, electrical effects, and irradiation).…”