Quality by Design (QbD) approach to optimize the formulation of a bilayer combination tablet (Telmiduo®) manufactured via high shear wet granulation.

A bilayer tablet, which consisted of telmisartan and amlodipine besylate, was formulated based on a Quality by Design (QbD) approach. The control and response factors were determined based on primary knowledge and the target values of the control tablet (Twynsta®). A D-optimal mixture design was used to obtain the optimal formulations in terms of D-mannitol, crospovidone, and MCC for the telmisartan layer, and CCM-Na, PVP K25, and Prosolv for the amlodipine layer. The quantitative effects of the different formulation factors on the response factors were accurately predicted using the equations of best fit and a strong linearity was observed between the predicted and actual values of the response factors. The optimized bilayer tablet was obtained using a numeric optimization technique and was characterized compared with a control (Twynsta®) by using various physical evaluations and in vivo pharmacokinetic parameters. The physical stability of Telmiduo® was greater than that of Twynsta® owing to the improvement of formulation factors. The in vivo pharmacokinetic parameters suggested that Telmiduo® might have pharmaceutical equivalence and bioequivalence with Twynsta®. Therefore, the bilayer tablet that consisted of telmisartan and amlodipine besylate could be produced using a more economical and simpler method than that used to produce Twynsta®. Moreover, the suitability of QbD for effective product development in the pharmaceutical industry was shown.

Characterization of monolithic matrix patch system containing tulobuterol.

The aim of this study was to investigate the effect of the functional groups in acrylic adhesive on tulobuterol uptake, release rate and permeation rate across rat dorsal skin. In addition, the relationship between these parameters was identified in order to formulate the monolithic matrix patch system. Seven acrylate pressure sensitive adhesives were used in this study with three different functional groups as follows: (1) no functionality (DT-4098), (2) hydroxyl group (DT-2287, DT-2510, DT-2525, DT-2516), and (3) carboxyl group (DT-2353, DT-2852). Tulobuterol-uptake in PSA was determined by the drug-uptake method. The amount of tulobuterol-uptake in acrylic polymers with a carboxyl group was higher than those in acrylate pressure sensitive adhesives with either a hydroxyl group or a nonfunctional group. The release rate of tulobuterol from the monolithic patches was evaluated and DT-2353 and DT-2852, which contained a carboxyl group, showed lower release rates of tulobuterol than the other acrylate pressure sensitive adhesives. The skin permeation of tulobuterol was investigated using excised rat dorsal skin and the permeation rate of tulobuterol from DT-2353 and DT-2852 was also lower than the other acrylate pressure sensitive adhesives. Taking into consideration the relationship between all the parameters, pressure sensitive adhesives can be categorized into two groups: those containing a carboxylic acid functional group and those containing a non-carboxylic group. These results indicate that there was an interaction between the secondary amino group of tulobuterol and the carboxyl group of the acrylate polymer. Therefore, we suggest that a drug's chemical structure and functional groups in pressure sensitive adhesives must be considered in order to formulate a transdermal patch system.

A new formulation of controlled release amitriptyline pellets and its in vivo/in vitro assessments.

Controlled-release amitriptyline pellets (ATP) were formulated and its oral bioavailability was assessed in human volunteers after oral administration under fasting conditions. Core pellets were prepared using a CF granulator by two different methods (powder layering and solvent spraying) and coated with Eudragit RS or RL 100. Physical characteristics and dissolution rates of core pellets and coated pellets were evaluated to optimize the formulation. Powder layering method resulted in a better surface morphology than solvent spraying method. However, physical properties of the products were poorer when prepared by powder layering method with respect to hardness, friability and density. The dissolution profile of amitriptyline coated with Eudragit RS 100 was comparable to that of commercially available amitriptyline enteric-coated pellets (Saroten retard). After the oral administration of both products at the dose of 50 mg, the mean maximum concentrations (Cmax) were 36.4 and 29.7 ng/mL, and the mean areas under the concentration-time curve (AUC(0-96)) were 1180.2 and 1010.7 ng.h/mL for ATP and Saroten retard, respectively. The time to reach the maximum concentrations (Tmax) was 6 h for both formulations. Statistical evaluation suggested that ATP was bioequivalent to Saroten retard.