| ObjectiveAt present,about 70%of chemical drugs have the problem of poor solubility.These poorly soluble drugs usually improve their solubility by using amphiphilic substances,but the drug delivery systems（Special preparations such as microemulsion,micelles,polymeric micelles,microspheres,fat emulsions,etc.）that are solubilized by this method have various degrees of instability.For example,the drug will precipitate out and the solution will be equal after storage.These unstable phenomena will affect the effectiveness and safety of drug use.However,for these unstable phenomena,there is currently no effective evaluation method and method for timely detection and treatment,which leads to the quality problems caused by the inflow of drugs into the market,and even affects the safety of clinical drugs.Therefore,the establishment of a fast and accurate means and method for the evaluation of the stability of insoluble drug solubilization systems is of great significance for drug research,production process control,and quality evaluation.Coenzyme Q10（Coenzyme Q10,Co Q10）injection is often used clinically as a nutrient myocardium and a drug to improve myocardial metabolism,but because it is difficult to dissolve in water,it is often prepared by solubilizing surfactants such as Tween 80.However,the injection is unstable,and crystallization usually occurs within 3to 6 months,which is difficult to predict in advance and has certain safety risks.This study will take Coenzyme Q10 injection as the research object,with a view to establishing a method for quickly and accurately evaluating the stability of Coenzyme Q10 injection,and applying this method to the formulation screening and process optimization of Coenzyme Q10 injection.This paper evaluates the stability of Co Q10micelle from the perspective of micelle thermodynamics,using CMC as the index based on the interface characteristics and micelle thermodynamics theory.And through new indicators,the effect of co-solvents and additives on the stability of Co Q10 micelle system and the effect of different cooling processes after sterilization on the stability are studied in order to reduce or solve the unstable crystallization phenomenon of Co Q10micelle drug delivery system.The new evaluation index is used to evaluate the influence of freeze-thaw on the Co Q10 micelle system.After optimization,the stability test under long-term storage and other conditions provides ideas for evaluating product stability during actual production and transportation.Methods1.Establishment of stability evaluation method for Co Q10 micelle drug delivery systemCo Q10-HS15 micelle system was prepared by solubilizing coenzyme Q10 with polyethylene glycol stearate 15（Kolliphor HS15）.After treatment at three cooling rates after sterilization,the critical micelle concentration of micelle under various conditions was measured by surface tension method.The interfacial characteristics were analyzed and the thermodynamic parameters of the micelle(ΔG0mandΔG0ad)were calculated.This angle explains the differences in product quality.After treatment under the same conditions,the Co Q10 micelles were subjected to a constant temperature shaking experiment.In the experiment,the appearance of the micellar solution was observed,and the changes in the transmittance of the micelles were measured.At the same time,the changes in the cloud point of the micelles were measured.This result is compared with the CMC index.In addition,the particle size,PDI and zeta potential of the Co Q10micellar solution before and after the constant temperature shaking experiment were measured to determine the stability difference of the samples under different conditions.The stability changes before and after the samples were compared with the CMC index changes.2.Optimization of Co Q10 micelle drug delivery system and optimization of post-sterilization treatment processThe CMC of the Co Q10 micelle system was measured by surface tension method,and the interface characteristics were analyzed with the new CMC index to study the effect of the co-solvent S40 on the stability of the Co Q10-HS15 system and Co Q10-Tween80 system.Discuss the interaction between S40 and the two surfactants,and calculate the corresponding thermodynamic parameters to select the best ratio of HS15/S40 and Tween80/S40 from the perspective of energy.The effects of additives glucose and Na Cl on the stability of Co Q10 micelle system were studied,and the optimal additive content was selected.With three cooling methods,fast,medium and slow,the effect of post-sterilization treatment process on the thermodynamic stability of each system is explored,and a suitable cooling method is proposed.Under different post-sterilization treatment conditions,adding different amounts of glucose and Na Cl to the Co Q10-HS15 system is expected to improve the stability of the Co Q10 micelle system to changes in the cooling rate during the post-sterilization treatment process.3.Application and verification of the stability evaluation index of Co Q10 micelle drug delivery systemThe Co Q10-HS15 drug delivery system was freeze-thawed,and the micelle system was cycled once and twice,the system CMC was measured by the surface tension method,the thermodynamic parameters were calculated,and the effect of freeze-thaw on the thermodynamic stability of the system was explored.For all Co Q10 drug delivery systems that have undergone system optimization and process optimization,long-term and accelerated experiments are carried out.The same evaluation indicators are used to observe the appearance of the product,measure the transmittance of micelles,and evaluate the samples during placement.Results1.The evaluation method for evaluating the stability of the Co Q10 micellar drug delivery system using CMC as a new indicator is relatively safe,fast,and accurate.The CMC（mol/L）measured by the surface tension method at different cooling rates（slow,medium,and fast）are 1.438×10-4,2.555×10-4,3.013×10-4,respectively,and micelles treated by slower cooling methods can be obtained The lower CMC value,the values ofΔG0mandΔG0adunder all conditions are negative,andΔGm0/ΔG0adis less than 1,indicating that the adsorption behavior and micellization behavior of Co Q10-HS15micelles are spontaneous,and the adsorption behavior is the main process.The secondary process of micellization.The slower temperature-reduced micelles have lowerΔG0mandΔG0ad,that is,a more stable thermodynamic micelle system.In the constant temperature shaking experiment,the Co Q10 micelle system is gradually destroyed with the increase of the shaking time,and the light transmission rate of the three temperature-lowering micelle solutionsare reduced and produced Small aggregates.The particle size of the measured micelle solution was 17.68（18.37）nm,18.03（21.08）nm,and 19.63（19.96）nm,respectively.The PDI values were 0.049（0.223）,0.183（0.184）,and 0.086（0.286）.Zeta potentials are-3.08（-2.11）m V,-2.60（-2.06）m V,and-1.83（-1.32）m V（after the shaking acceleration test in parentheses）.The smaller particle size,more concentrated particle size distribution and larger Zeta potential value also reflect a more stable micelle system.The change trend of light transmittance decline rate,particle size,PDI and Zeta potential results are the same as the new index CMC evaluation results.Under the same conditions,using the cloud point as an indicator,there is no obvious difference in the measurement results,and the difference between the samples cannot be accurately measured.Combining the results of all parameters,the relationship between the new evaluation index CMC and the stability of Co Q10 micelles was established.2.Through the new evaluation system,the best co-solvent,the proportion of additives and the best way to cool down after sterilization are screened.Using CMC as an indicator,the HS15 system and the Tween80 system are measured separately.When HS15:S40=1:1,the smallest CMC value(0.649×10-4mol/L)can be obtained,CMCidea>CMCexp,activity coefficient f1<1,f2<1,interaction parameterβ<0,and the absolute value ofβis greater than ln（CMC1/CMC2）,there is synergy between the two,when the ratio is 1:1,the strongest effect can be achieved.At this ratio,the standard Gibbs free energyΔG0mof the micellization system is the smallest,and the standard Gibbs free energyΔG0adof the adsorption is the smallest,indicating that the micellization behavior and adsorption behavior of the mixed system are more spontaneous and thermodynamically stable better.Also for the Tween80 system,when Tween80/S40=3:1,the CMC value is the smallest(0.769×10-4mol/L),CMCidea>CMCexp,activity coefficient f1<1,f2<1,interaction parameterβ<0,And the absolute value ofβis greater than ln（CMC1/CMC2）,there is synergy between the two.When the ratio is 3:1,the strongest effect can be achieved,ΔG0mandΔG0adare also the smallest,which can obtain the most stable micelle system.For both systems,the addition of glucose and Na Cl can obtain good results.When the content of 5%glucose and 0.9%Na Cl is added,the minimum CMC value can be obtained,and the lowerΔG0mandΔG0advalues,at this time Achieve the most stable thermodynamic state.In addition,in the slowest gradient cooling mode,the single and mixed micelle drug delivery system can obtain the smallest CMC value,the lowestΔG0mandΔG0ad,the system has the best thermodynamic stability.The results of the additives glucose and Na Cl at different cooling rates show that the additives are beneficial to the stability of the Co Q10-HS15system temperature changes.3.The effect of freeze-thaw experiments on the stability of the system shows that both the first cycle and the second cycle of the freeze-thaw process will destroy the Co Q10 micelle solution,and the micelle solution becomes cloudy.In the Co Q10-HS15system,the light transmittance of the original sample,primary cycle and secondary cycle are 97.5%,87.8%and 77.3%,respectively.When heated,the micellar solution will gradually become clear,and the samples after treatment at 70°C,80°C,and 90°C were investigated.Freezing and thawing will damage the micelles,making the CMC value of the system larger and the thermodynamic stability worse.At the recovery temperature of 90°C,the CMC value of Co Q10-HS15 micelles returns to the original state as a whole,and the product stability is basically the same.Provides ideas for solving the problem of Co Q10 micellar injection freeze-thaw.4.Accelerated and long-term experimental investigations of all final optimized systems.The results showed that in the long-term and accelerated investigations,compared with the single micelle drug delivery system,Co Q10-HS15/S40 mixed micelle system and Co Q10-Tween80/S40 mixed glue The beam system can obtain the minimum CMC value,and can maintain a low CMC value,which is the best thermodynamically stable drug delivery system.The additive is also beneficial to the stability of the Co Q10 micelle delivery system,but the effect is weaker than the mixed micelle system.In addition,the accelerated test changes are more obvious,high temperature storage conditions are not conducive to the stability of Co Q10 micelle drug delivery system.ConclusionFor the Co Q10 micelle drug delivery system,the fast and accurate evaluation index CMC was found,and the stability evaluation system of the Co Q10 micelle system was established,that is,the CMC value of the micelle solution was measured by the surface tension method.Furthermore,the internal structural changes of micelles were analyzed through the interface characteristics and thermodynamic parameters of the micelle system,and the stability of Co Q10 micelle system was quickly and accurately evaluated.Using this evaluation method,the best co-solvent ratio of Co Q10 micelles,the best additive content and the best scheme of cooling method were screened,and the stability of Co Q10 micelle system was improved.Finally,the new index CMC is applied to the stability evaluation of Co Q10 micelle system under freeze-thaw conditions;the stability evaluation under long-term storage conditions also validates the optimization results.Provide theoretical explanation and ideas for evaluating the stability of Co Q10micelle during actual production and transportation. |
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