A robust experimental design method to optimize formulations of retinol solid lipid nanoparticles.

A robust experimental design method was developed using a response surface methodology and models to facilitate the development process of retinol solid lipid nanoparticles (SLNs). The SLNs were evaluated to determine how different parameters including lipid and surfactant affect size and encapsulation efficiency. This was conducted using factorial analysis and a robust design (RD) method was used to achieve optimal formulations. Two models were developed based on the RD principle and both mean and variance of the response characteristics were estimated functionally using the least squares method. They proved useful in formulation studies aiming to develop optimum by allowing a systematic and reliable design method. A model for maximizing the overall desirability represented by the geometric mean of all objectives was found to provide a better solution. The newly designed method provides useful information to characterize significant factors and obtain optimum formulations, thereby allowing a systematic and reliable design method.

Time-oriented experimental design method to optimize hydrophilic matrix formulations with gelation kinetics and drug release profiles.

A new experimental design methodology was developed by integrating the response surface methodology and the time series modeling. The major purposes were to identify significant factors in determining swelling and release rate from matrix tablets and their relative factor levels for optimizing the experimental responses. Properties of tablet swelling and drug release were assessed with ten factors and two default factors, a hydrophilic model drug (terazosin) and magnesium stearate, and compared with target values. The selected input control factors were arranged in a mixture simplex lattice design with 21 experimental runs. The obtained optimal settings for gelation were PEO, LH-11, Syloid, and Pharmacoat with weight ratios of 215.33 (88.50%), 5.68 (2.33%), 19.27 (7.92%), and 3.04 (1.25%), respectively. The optimal settings for drug release were PEO and citric acid with weight ratios of 191.99 (78.91%) and 51.32 (21.09%), respectively. Based on the results of matrix swelling and drug release, the optimal solutions, target values, and validation experiment results over time were similar and showed consistent patterns with very small biases. The experimental design methodology could be a very promising experimental design method to obtain maximum information with limited time and resources. It could also be very useful in formulation studies by providing a systematic and reliable screening method to characterize significant factors in the sustained release matrix tablet.