Xingchu Gong

Application of Quality by Design to the Process Development of Botanical Drug Products: A Case Study

This paper was designed to assess the value of quality by design (QbD) to improve the manufacturing process understanding of botanical drug products. Ethanol precipitation, a widely used unit operation in the manufacture of botanical drug products was employed to illustrate the use of QbD, taking the process of danshen (the dry root of Salvia miltiorrhiza Bunge) as an example. The recovery of four active pharmaceutical ingredients (APIs) and the removal of saccharides were used to represent the performance of ethanol precipitation. Potentially critical variables, including density of concentrate, ethanol consumption, and settling temperature were identified through risk assessment methods. Design of experiments (DOE) was used to evaluate the effects of the potentially critical factors on the performance of ethanol precipitation. It was observed that higher density of concentrate leads to higher removal of saccharides, but results in lower recovery of APIs. With the rise of ethanol consumption, the recovery of different APIs behaves in different ways. A potential design space of ethanol precipitation operation was established through DOE studies. The results in this work facilitate the enhanced understanding of the relationships between multiple factors (material attributes and process parameters) and the performance of ethanol precipitation. This case study demonstrated that QbD is a powerful tool to develop manufacturing process of botanical drug products.

Monitoring batch-to-batch reproducibility of liquid–liquid extraction process using in-line near-infrared spectroscopy combined with multivariate analysis

Traditional Chinese medicine (TCM) products are usually manufactured through batch processes. To improve batch-to-batch reproducibility, the feasible approaches for real-time monitoring of batch evolution need to be developed. In-line near-infrared (NIR) spectroscopy combined with multivariate data analysis as an efficient process analytical technology (PAT) tool, is presented in this study for real-time batch process monitoring. Liquid-liquid extraction is a widely used purification technology in the TCM manufacture, and selected as the example to demonstrate the effectiveness of this PAT tool. Multi-way partial least squares (MPLS) model was developed based on in-line measured NIR spectral data of ten normal operation condition (NOC) batches. Three kinds of multivariate control charts (scores, Hotelling T(2) and DModX) were used to monitor the evolution of six test batches with artificial batch variations, including the change of starting material quality attributes and abnormal operation conditions. The approach was found very effective for real-time monitoring of process deviations from NOC batches. It is an alternative promising tool for monitoring batch reproducibility of the unit operations during the manufacture of TCM.

Solid-Liquid Equilibria of D-Glucose, D-Fructose and Sucrose in the Mixture of Ethanol and Water from 273.2 K to 293.2 K

Abstract Experimental data on the solubility of D-glucose, D-fructose and sucrose in the mixed solvents composed of water and ethanol from 273.2 to 293.2 K were determined. The solubility of D-glucose, D-fructose and sucrose decreased as the ethanol content increased in the mixed solvent. The solubility of D-glucose, D-fructose and sucrose decreased with decreasing equilibrium temperature. The modified UNIQUAC model, S-UNIFAC model and mS-UNIFAC model were applied to predict the solid-liquid equilibria. The prediction results were compared and discussed. Better prediction accuracy was generated using the modified UNIQUAC model.

Optimization of the Ethanol Recycling Reflux Extraction Process for Saponins Using a Design Space Approach

A solvent recycling reflux extraction process for Panax notoginseng was optimized using a design space approach to improve the batch-to-batch consistency of the extract. Saponin yields, total saponin purity, and pigment yield were defined as the process critical quality attributes (CQAs). Ethanol content, extraction time, and the ratio of the recycling ethanol flow rate and initial solvent volume in the extraction tank (RES) were identified as the critical process parameters (CPPs) via quantitative risk assessment. Box-Behnken design experiments were performed. Quadratic models between CPPs and process CQAs were developed, with determination coefficients higher than 0.88. As the ethanol concentration decreases, saponin yields first increase and then decrease. A longer extraction time leads to higher yields of the ginsenosides Rb1 and Rd. The total saponin purity increases as the ethanol concentration increases. The pigment yield increases as the ethanol concentration decreases or extraction time increases. The design space was calculated using a Monte-Carlo simulation method with an acceptable probability of 0.90. Normal operation ranges to attain process CQA criteria with a probability of more than 0.914 are recommended as follows: ethanol content of 79–82%, extraction time of 6.1–7.1 h, and RES of 0.039–0.040 min−1. Most of the results of the verification experiments agreed well with the predictions. The verification experiment results showed that the selection of proper operating ethanol content, extraction time, and RES within the design space can ensure that the CQA criteria are met.

Quantitative 1H NMR method for hydrolytic kinetic investigation of salvianolic acid B

This work presents an exploratory study for monitoring the hydrolytic process of salvianolic acid B (Sal B) in low oxygen condition using a simple quantitative (1)H NMR (Q-NMR) method. The quantity of the compounds was calculated by the relative ratio of the integral values of the target peak for each compound to the known amount of the internal standard trimethylsilyl propionic acid (TSP). Kinetic runs have been carried out on different initial concentrations of Sal B (5.00, 10.0, 20.0mg/mL) and temperatures of 70, 80, 90°C. The effect of these two factors during the transformation process of Sal B was investigated. The hydrolysis followed pseudo-first-order kinetics and the apparent degradation kinetic constant at 80°C decreased when concentration of Sal B increased. Under the given conditions, the rate constant of overall hydrolysis as a function of temperature obeyed the Arrhenius equation. Six degradation products were identified by NMR and mass spectrometric analysis. Four of these degradation products, i.e. danshensu (DSS), protocatechuic aldehyde (PRO), salvianolic acid D (Sal D) and lithospermic acid (LA) were further identified by comparing the retention times with standard compounds. The advantage of this Q-NMR method was that no reference compounds were required for calibration curves, the quantification could be directly realized on hydrolyzed samples. It was proved to be simple, convenient and accurate for hydrolytic kinetic study of Sal B.

Unit operation optimization for the manufacturing of botanical injections using a design space approach: a case study of water precipitation.

Quality by design (QbD) concept is a paradigm for the improvement of botanical injection quality control. In this work, water precipitation process for the manufacturing of Xueshuantong injection, a botanical injection made from Notoginseng Radix et Rhizoma, was optimized using a design space approach as a sample. Saponin recovery and total saponin purity (TSP) in supernatant were identified as the critical quality attributes (CQAs) of water precipitation using a risk assessment for all the processes of Xueshuantong injection. An Ishikawa diagram and experiments of fractional factorial design were applied to determine critical process parameters (CPPs). Dry matter content of concentrated extract (DMCC), amount of water added (AWA), and stirring speed (SS) were identified as CPPs. Box-Behnken designed experiments were carried out to develop models between CPPs and process CQAs. Determination coefficients were higher than 0.86 for all the models. High TSP in supernatant can be obtained when DMCC is low and SS is high. Saponin recoveries decreased as DMCC increased. Incomplete collection of supernatant was the main reason for the loss of saponins. Design space was calculated using a Monte-Carlo simulation method with acceptable probability of 0.90. Recommended normal operation region are located in DMCC of 0.38–0.41 g/g, AWA of 3.7–4.9 g/g, and SS of 280–350 rpm, with a probability more than 0.919 to attain CQA criteria. Verification experiment results showed that operating DMCC, SS, and AWA within design space can attain CQA criteria with high probability.

Multi-criteria optimization for ultrasonic-assisted extraction of antioxidants from Pericarpium Citri Reticulatae using response surface methodology, an activity-based approach.

An activity-based approach to optimize the ultrasonic-assisted extraction of antioxidants from Pericarpium Citri Reticulatae (Chenpi in Chinese) was developed. Response surface optimization based on a quantitative composition-activity relationship model showed the relationships among product chemical composition, antioxidant activity of extract, and parameters of extraction process. Three parameters of ultrasonic-assisted extraction, including the ethanol/water ratio, Chenpi amount, and alkaline amount, were investigated to give optimum extraction conditions for antioxidants of Chenpi: ethanol/water 70:30 v/v, Chenpi amount of 10 g, and alkaline amount of 28 mg. The experimental antioxidant yield under the optimum conditions was found to be 196.5 mg/g Chenpi, and the antioxidant activity was 2023.8 μmol Trolox equivalents/g of the Chenpi powder. The results agreed well with the second-order polynomial regression model. This presented approach promised great application potentials in both food and pharmaceutical industries.

Design Space Development for the Extraction Process of Danhong Injection Using a Monte Carlo Simulation Method

A design space approach was applied to optimize the extraction process of Danhong injection. Dry matter yield and the yields of five active ingredients were selected as process critical quality attributes (CQAs). Extraction number, extraction time, and the mass ratio of water and material (W/M ratio) were selected as critical process parameters (CPPs). Quadratic models between CPPs and CQAs were developed with determination coefficients higher than 0.94. Active ingredient yields and dry matter yield increased as the extraction number increased. Monte-Carlo simulation with models established using a stepwise regression method was applied to calculate the probability-based design space. Step length showed little effect on the calculation results. Higher simulation number led to results with lower dispersion. Data generated in a Monte Carlo simulation following a normal distribution led to a design space with a smaller size. An optimized calculation condition was obtained with 10000 simulation times, 0.01 calculation step length, a significance level value of 0.35 for adding or removing terms in a stepwise regression, and a normal distribution for data generation. The design space with a probability higher than 0.95 to attain the CQA criteria was calculated and verified successfully. Normal operating ranges of 8.2-10 g/g of W/M ratio, 1.25-1.63 h of extraction time, and two extractions were recommended. The optimized calculation conditions can conveniently be used in design space development for other pharmaceutical processes.

Process development for the decoloration of Panax notoginseng extracts: A design space approach

A systematic, yet simple method for the decoloration of Panax notoginseng extracts has been developed by static adsorption tests and response surface methodology. Through static adsorption experiment screening, acidic alumina was selected because of its high decoloration ratio and saponin recovery ratios. Using response surface methodology, the correlation between the process parameters (i.e., sample volume and flow rate) and decoloration performance was modeled. A design space of the decoloration process was subsequently established through the proposed models. The verification experimental values were in good agreement with the predicted values. The design space was proven reliable, because all the verification experimental results attained the criteria for design space development. Moreover, most of the saponins adsorbed by the acidic alumina could be recovered through dynamic desorption using water and ethanol. The method developed in the current study is highly efficient, flexible, and easy to control, thus providing a promising approach for the decoloration of Panax notoginseng extracts with consistent decoloration performance.

Removing Tannins from Medicinal Plant Extracts Using an Alkaline Ethanol Precipitation Process: A Case Study of Danshen Injection

The alkaline ethanol precipitation process is investigated as an example of a technique for the removal of tannins extracted from Salviae miltiorrhizae Radix et Rhizoma for the manufacture of Danshen injection. More than 90% of the tannins can be removed. However, the recoveries of danshensu, rosmarinic acid, and salvianolic acid B were less than 60%. Total tannin removal increased as the refrigeration temperature decreased or the amount of NaOH solution added increased. Phenolic compound recoveries increased as refrigeration temperature increased or the amount of NaOH solution added decreased. When operated at a low refrigeration temperature, a relative high separation selectivity can be realized. Phenolic compound losses and tannin removal were mainly caused by precipitation. The formation of phenol salts, whose solubility is small in the mixture of ethanol and water used, is probably the reason for the precipitation. A model considering dissociation equilibrium and dissolution equilibrium was established. Satisfactory correlation results were obtained for phenolic compound recoveries and total tannin removal. Two important parameters in the model, which are the water content and pH value of alkaline supernatant, are suggested to be monitored and controlled to obtain high batch-to-batch consistency.