Study On Preparation Technology,quality Evaluation And Pharmacokinetics Of Injectable Diclofenac Sodium Oil Suspension

Objective:Over the past few decades,based on the needs of animal welfare,economic benefits,and food safety,precaution and treatment of animal pain and inflammation is of great significance.Diclofenac sodium（DS）is the third-generation of non-steroidal anti-inflammatory drug and exhibits excellent antipyretic,analgesic,anti-inflammatory and anti-rheumatic activities.However,the drawbacks of DS,including high plasma protein binding rate,short half-life and rapid elimination,limit its clinical applications.In order to address these problems,5%diclofenac sodium oil suspension was prepared to prolong the retention time in vivo,reduce the frequency of administration,and improve the convenience and medication safety.The quality of DS oil suspension was evaluated in this research,and the release property in vivo was investigated.Methods:Ball mill gringing method was used to prepare DS oil suspension.Parameters,including appearance,particle size,sedimentation volume ratio,redispersibility,etc.were regarded as indicators for the optimization of the formulation and preparation process.Quality standards were established following the instructions of Techniqual Guidelines for Veterinary Medicine Research.Qualities of three batches of samples（20210104,20210105,20210106）were assessed.Related substances and content were quantified by high performance liquid chromatography（HPLC）.Influcing factor tests and acceleration experiments were performed to investigate the stability of DS oil suspension.Method for the quantification of the plasmic DS was established via HPLC.Homemade DS oil suspension and commercial DS injection were given to SD rats by intramuscular injection at a single dosage of 10 mg/kg,and pharmacokinetic properties were investigated.Results:The prescription and preparation process of DS oil suspension are as follows:1.Add 0.5 g of aluminum stearate and 0.2 g of lecithin to 90 m L of soybean oil,while stirring and heating until all the ingredients are completely dissolved and the oil solution becomes transparent and golden.Allow the mixture to cool room temperature to obtain the oil gel.2.Add 0.4 g of Span 80 and 0.2 g of Vitamin E to the oil gel,and mix well.3.Gradually add 5 g of DS to the above mixture while stirring.Make up the mixture to 100 m L with soybean oil and mix well to obtain the initial DS oil suspension.4.Pour the initial oil suspension into the ball mill and grind for 3minutes at the speed of 800 rpm（5 cycles,5 min of break in-between）to obtain the final DS oil suspension.The sedimentation volume ratios of the three batches of samples were 0.97,0.98,and 0.97,the redispersibilities were 95%,90%,and 95%,the total impurities were0.21%,0.17%,0.14%,and the DS content were 96.26%,96.16%,97.05%,respectively.All the results meet the quality standards.The established HPLC methods for the quantification of related substances and content of DS oil suspension are highly specific,precise and very stable.The established method for the determination of related substances shows an excellent linear in the range of 5.25～1050.0μg/m L,with the linear fitting equation of A=0.2443C-0.0935 and the correlation coefficient R² of 0.9999.The quantification of the content exhibits a good linear in the range of 0.1～0.6 mg/m L with the linear fitting equation of A=265.6521C-1.2496 and the correlation coefficient R² of0.9997.The content decreased after storage at 60°C for 10 days.No significant moisture absorption was observed after storing the sample with the humidity of 95%for 10 days,and the content had no obvious changes.Exposing DS oil suspension to5000 lx for 10 days led to a significant decrease of content but the appearance maintained the same.Under the conditions of high temperature,high humidity,and strong light irradiation,the impurity content of the sample increased,but it was still within the required range.Acceleration experiments for 3 months,the inspection results of all projects were up to the mustard.The determination of the plasmatic DS was established by HPLC using indomethacin as an internal standard.The method shows a good linear in the range of 0.05-20.0μg/m L with a linear fitting equation of Y=0.5481C+0.0036 and the correlation coefficient R² of 0.9999.The established method is highly specific,precise and accurate,stable and can be used for the detection of the plasmatic DS.With the single-dose intramuscular injection,T_1/2βof diclofenac sodium oil suspension and injection were 6.40±1.15 h and 4.71±1.17 h,respectively.Conclusion:In this study,5%DS oil suspension was successfully prepared,and the quality standard was preliminarily established.The influencing factor tests demonstrated that the preparation should be hermetically stored under cool and dark.Compared with the commercial DS injection,DS oil suspension can prolong the half-life time,increase the average retention time,improve the bioavailability,and achieve a stable release of DS.The prepared 5%DS oil suspension,with a certain sustained release property,provides a powerful strategy to enhance the clinical medication safety of DS.