Patent Description:
Prostaglandin E1 (PGE1) is a natural endogenous vasodilator, which can be synthesized by human cells. It is an important substance that regulates cell function. It does not accumulate in the body, does not produce tolerance, and it's non-toxic without damaging side effects. It has a definite therapeutic effect and is superior to exogenous drugs. PGE1 has extremely strong physiological activity and a wide range of pharmacological activities. It can be used clinically in cardiovascular and cerebrovascular diseases, diabetic complications, respiratory diseases, pulmonary hypertension, hepatorenal syndrome (HRS), liver failure, nephropathy, etc. Studies have found that prostaglandin E1 not only has the effects of dilating blood vessels and reducing heart load, but also has the effects of excreting sodium, diuresis, strengthening the heart, improving coronary circulation, protecting myocardium, improving microcirculation and the like.

However, the common prostaglandin E1 fat emulsion injections currently on the market also have several obvious shortcomings: poor chemical stability, decreased content of prostaglandin E1 caused by high temperature sterilization, significantly increased content of degradation product PGA1, harsh product storage conditions (<NUM>~<NUM>), and short effective period of only <NUM> year. Because prostaglandin E1 itself is an inflammatory substance, it has a strong pain when clinically applied to the human body, causing phlebitis, and limiting the product promotion.

In response to the above shortcomings, Chongqing Yaopharma developed a lyophilized emulsion of prostaglandin E1 (ZL201010168597. <NUM>)-Udil. The marketed product avoids the content loss caused by high temperature sterilization through sterilization by filtration, and overcomes the shortcoming of poor stability of prostaglandin E1 in aqueous preparations, and prolongs the effective period. However, cyclodextrin is used as a lyoprotectant in its formulation. Because there is a certain safety risk when cyclodextrin is used as an excipient for injection, especially the administration of β-cyclodextrin by injection can cause obvious nephrotoxicity, hemolysis, and necrosis at the injection site. The safety hazard of the preparation is significant, and the problem of injection pain is not solved (Instructions of Udil).

Prostaglandin E1 alkyl esters are currently considered to be prodrugs of prostaglandin E1. For example, <CIT> discloses prostaglandin E1 alkyl esters (C1-<NUM>) for the treatment of impotence. It is believed that prostaglandin E1 alkyl esters can be better absorbed through the skin by enhancing lipid solubility, and subsequently decomposed into prostaglandin E1 by hydrolase to take effect, so it is a prodrug; <CIT> discloses a prostaglandin E1 alkyl ester (C1-<NUM>) external preparation, which contains prostaglandin E1 alkyl ester as a prodrug, an oily vehicle, a skin permeation enhancer and an anti-irritant agent.

However, the inventors have unexpectedly found in the research that prostaglandin E1 methyl ester itself has strong biological activity and has a good prospect of preparing medicines. A fat emulsion preparation of alprostadil methyl ester is disclosed in the <CIT>. However, the fat emulsion of alprostadil methyl ester prepared by us according to the examples thereof during the research is found to contain a significant number of large-size (><NUM>) emulsion droplets and fail to meet the requirement of emulsion droplet size, when measured using a new method, light blockage method in the United States Pharmacopoeia for the determination of the size of the emulsion droplet (the original common dynamic light scattering method cannot accurately determine the number of large-size particles above <NUM>). Large emulsion droplets (><NUM>) can block capillaries and cause embolism, which poses a significant safety risk. In the United States, there has been a medical accident that the injection of large particles of fat emulsion lead to the death of a patient. Investigations and studies have shown that it is caused by the presence of emulsion particles larger than <NUM> in the emulsion. Therefore, in <NUM>, the United States Pharmacopeia formulated the detection methods and standards for determining the large particle size of emulsions.

<CIT> has provided a preparation relating to a PGE1-containing fat emulsion with excellent qualities which is superior to the conventional ones bacteriologically or in thermal or prolonged stability. The preparation is a freeze-dried one derived from a fat emulsion which contains PGE1, an oily component, an emulsifier and water and has a liquid nature (pH value) within the neutral region.

<CIT> has disclosed an alprostadil freeze-dried emulsion composition for injection. The alprostadil freeze-dried emulsion composition comprises alprostadil, an oil phase, a water phase and an emulsifying agent, wherein the oil phase is prepared from soybean oil and safflower seed oil according to the weight ratio of <NUM>:<NUM>-<NUM>:<NUM>; the alprostadil freeze-dried emulsion composition further comprises <NUM>-<NUM> parts by weight of DHA.

<CIT>has disclosed a lyophilized emulsion of flurbiprofen axetil for injection and a preparation method thereof. Ratio of various auxiliary materials and a preparation process are strictly controlled by researchers, a mixed freeze-drying protective agent with a special proportioning is used, and the lyophilized emulsion containing flurbiprofen axetil is prepared.

<CIT>has disclosed a preparation relating to a PGE1-containing fat emulsion with excellent qualities which is superior to the conventional ones bacteriologically or in thermal or prolonged stability. The preparation is a freeze-dried one derived from a fat emulsion which contains PGE1, an oily component, an emulsifier and water and has a liquid nature (pH value) within the neutral region.

<CIT> has disclosed a application of high-dosage glycerinum in a freeze-thawing tolerable fat emulsion and the freeze-thawing tolerable fat emulsion; the high-dosage glycerinum is that the content of the glycerinum in the emulsion is more than or equal to <NUM> w/v%; the maximal use amount of the glycerinum is <NUM> w/v% of the total weight of the emulsion; and, when the content of oil solution in the emulsion is <NUM>-<NUM> w/v%, the use amount of the glycerinum is more than or equal to <NUM>/<NUM> of the amount of oil in the emulsion.

In view of the shortcomings and deficiencies of existing products, the disclosure aims to provide a new type of prostaglandin E1 methyl ester product with good stability, low safety risk and better efficacy.

An object of the disclosure is to provide a method for producing a lyophilized preparation of prostaglandin E1 methyl ester for injection.

Another object of the disclosure is to provide a lyophilized preparation of prostaglandin E1 methyl ester for injection prepared by the production method.

A further object of the disclosure is to provide use of the lyophilized preparation of prostaglandin E1 methyl ester for injection.

To achieve the above objects, in one aspect, the disclosure provides a method for producing a lyophilized preparation of prostaglandin E1 methyl ester for injection, wherein the method includes producing a lyophilized preparation with the following components as raw materials in weight percentage: <NUM>-<NUM>% of prostaglandin E1 methyl ester, <NUM>-<NUM>% of an oil for injection, <NUM>-<NUM>% of an emulsifier, <NUM>-<NUM>% of a co-emulsifier , <NUM>-<NUM>% of a lyoprotectant, <NUM>-<NUM>% of glycerin, an appropriate amount of pH regulator, and a balance of water for injection;
wherein the method includes the following steps:.

According to some specific embodiments of the disclosure, the oil for injection is selected from one or more of soybean oil, medium chain oil, olive oil, tea oil, corn oil or castor oil.

According to some specific embodiments of the disclosure, the emulsifier is selected from lecithin and/or soybean phospholipid.

According to some specific embodiments of the disclosure, the co-emulsifier is selected from one or more of oleic acid, palmitic acid, stearic acid, linolenic acid, linoleic acid and sodium oleate.

According to some specific embodiments of the disclosure, the lyoprotectant is selected from one or more of lactose, sucrose, trehalose, mannitol, glucose and maltose.

According to some specific embodiments of the disclosure, the method includes producing the lyophilized preparation with the following components as raw materials in weight percentage: <NUM>-<NUM>% of prostaglandin E1 methyl ester, <NUM>-<NUM>% of the oil for injection, <NUM>-<NUM>% of the emulsifier, <NUM>-<NUM>% of the co-emulsifier, <NUM>-<NUM>% of the lyoprotectant, <NUM>-<NUM>% of glycerin, an appropriate amount of pH regulator, and a balance of water for injection.

According to some specific embodiments of the disclosure, the method includes producing the lyophilized preparation with the following components as raw materials by weight: <NUM>-<NUM> parts of prostaglandin E1 methyl ester, <NUM>-<NUM> parts of soybean oil, <NUM>-<NUM> parts of lecithin, <NUM>-<NUM> parts of sodium oleate, <NUM>-<NUM> parts of lactose, <NUM>-<NUM> parts of glycerin, an appropriate amount of sodium citrate or hydrochloric acid, and a balance of water for injection based on <NUM>×<NUM><NUM> parts of the total weight of raw materials.

According to some specific embodiments of the disclosure, the amount of the pH adjusting agent is such that the pH of the mixed solution is adjusted to <NUM>-<NUM> when the mixed solution is made up to the full volume with water for injection.

According to some specific embodiments of the disclosure, step d is to obtain the initial emulsion by shearing at a constant temperature of <NUM> to <NUM>.

According to some specific embodiments of the disclosure, the lyophilization process of step f includes pre-freezing at -<NUM> to -<NUM> for <NUM>-<NUM> minutes, and then vacuuming at <NUM>-<NUM> mTorr (<NUM>-<NUM> Pa) for <NUM>-<NUM> minutes at -<NUM> to -<NUM>, then vacuuming at <NUM>-70mTorr (<NUM>-<NUM> Pa) for <NUM>-<NUM> minutes at <NUM> to <NUM>, and then vacuuming at <NUM>-45mTorr (<NUM>-<NUM> Pa) for <NUM>-<NUM> minutes at <NUM> to <NUM>.

According to some specific embodiments of the disclosure, the lyophilization process of step f includes pre-freezing at -<NUM> for <NUM> minutes, and then vacuuming at <NUM> mTorr (<NUM> Pa) for <NUM> minutes at -<NUM>, then vacuuming at 60mTorr (<NUM> Pa) for <NUM> minutes at <NUM>, and then vacuuming at 40mTorr (<NUM> Pa) for <NUM> minutes at <NUM>.

According to some specific embodiments of the disclosure, wherein the lyophilized preparation comprises the following components per <NUM> before lyophilization: <NUM>-<NUM> of prostaglandin E1 methyl ester, <NUM>-<NUM> of soybean oil, <NUM>-<NUM> of lecithin, <NUM>-<NUM> of sodium oleate, <NUM>-<NUM> of lactose, and <NUM>-<NUM> of glycerin.

It can be understood that the "per <NUM>" in "the lyophilized preparation comprises the following components per <NUM> before lyophilization" in the disclosure refers to every <NUM> of the prepared solution before lyophilization; that is, an aqueous solution containing each component.

According to some specific embodiments of the disclosure, the weight ratio of the lyoprotectant to prostaglandin E1 methyl ester is <NUM>-<NUM>:<NUM>.

In another aspect, the disclosure also provides a lyophilized preparation of prostaglandin E1 methyl ester for injection prepared by the production method of the disclosure.

In a further aspect, the disclosure also provides use of the lyophilized preparation of prostaglandin E1 methyl ester for injection in the preparation of a vasodilator.

According to some specific embodiments of the disclosure, the vasodilator is used to treat microcirculation disorders.

According to some specific embodiments of the disclosure, the microcirculation disorder is caused by thromboangiitis obliterans, arteriosclerosis obliterans, diabetes, frostbites, burns or bedsores.

The inventor has unexpectedly found in the research that prostaglandin E1 methyl ester itself has strong biological activity, and its anticoagulant and vasodilator activities are superior to those of prostaglandin E1, and it has a good potential for drug development. Through further formulation research, the inventor has chosen a lyophilized agent as the preparation form of prostaglandin E1 methyl ester, and unexpectedly found that the lyophilized preparation of prostaglandin E1 methyl ester prepared by the disclosure has the following remarkable features compared with existing preparations:.

The technical solutions of the disclosure will be described in detail below in conjunction with the drawings and examples, but the protection scope of the disclosure includes but is not limited to these.

The starting material PGE1 (<NUM>, <NUM> mmol) was added to a three-necked flask, and then a prepared <NUM> dry THF/Et<NUM>O solution was added and stirred to dissolve. Under ice bath conditions, MeI (<NUM>, <NUM>) solution was slowly added dropwise to the reaction solution, and after the completion of dropwise addition, KOH (<NUM>, <NUM> mmol) and Bu<NUM>NBr (<NUM>, <NUM> mmol) were added. After the reaction solution was stirred for <NUM>, it was heated to room temperature and monitored by TLC until the end of the reaction. The reaction was quenched by adding <NUM> of water. It was extracted with EtOAc (<NUM>×<NUM>), and the organic phases were combined, dried over anhydrous Na<NUM>SO<NUM> and filtered. The filtrate was concentrated under reduced pressure and purified by column chromatography (eluent n-hexane/EA = <NUM>/<NUM>) to obtain a white solid product (<NUM>, <NUM>% yield).

<NUM>HNMR (<NUM>, DMSO) (ppm):<NUM> (s, <NUM>), <NUM>(s, <NUM>), <NUM>(s, <NUM>), <NUM>(s, <NUM>), <NUM>(s, <NUM>), <NUM>-<NUM>(m, <NUM>)<NUM>-<NUM>(m, <NUM>), <NUM>(s, <NUM>).

The starting material PGE1 (<NUM>, <NUM> mmol) was added to a three-necked flask, and then a prepared <NUM> dry THF/Et<NUM>O solution was added and stirred to dissolve. Under ice bath conditions, EtBr (<NUM>, <NUM>) solution was slowly added dropwise to the reaction solution, and after the completion of dropwise addition, KOH (<NUM>, <NUM> mmol) and Bu<NUM>NBr (<NUM>, <NUM> mmol) were added. After the reaction solution was stirred for <NUM>, it was heated to room temperature and monitored by TLC until the end of the reaction. The reaction was quenched by adding <NUM> of water. It was extracted with EtOAc (<NUM>×<NUM>), and the organic phases were combined, dried over anhydrous Na<NUM>SO<NUM> and filtered. The filtrate was concentrated under reduced pressure and purified by column chromatography (eluent n-hexane/EA = <NUM>/<NUM>) to obtain a white solid product (<NUM>, <NUM>% yield).

<NUM>HNMR (<NUM>, DMSO) (ppm): <NUM>(s, <NUM>), <NUM>(s, <NUM>), <NUM>(s, <NUM>), <NUM>(s, <NUM>), <NUM>(s, <NUM>), <NUM>-<NUM>(m, <NUM>)<NUM>-<NUM>(m, <NUM>), <NUM>(s, <NUM>).

The preparation process was the same as Example <NUM>.

It is prepared according to Example <NUM> in <CIT>.

The lyoprotectant used in the formulation of the disclosure (Example <NUM> of this disclosure) was added to the preparation obtained in Comparative Example <NUM> for lyophilization.

When healthy adult SD rats were anesthetized by intraperitoneal injection of <NUM>% chloral hydrate, fresh whole blood was collected from the abdominal aorta and added to a centrifuge tube anticoagulated with <NUM>% sodium citrate solution, and centrifuged at <NUM> rpm for <NUM> minutes to remove the upper platelet-rich plasma (PRP) for use. The tube having PRP removed was further centrifuged at <NUM> rpm for <NUM> minutes, and the upper clarified plasma (PPP) was removed for use. In the experiment, Techlink model LBY-NJ4 <NUM>-channel platelet aggregator was used to determine the anticoagulant efficacy of each compound.

Into a sample cup containing 300µL of PRP, 2µL of <NUM> PGE1, Compound <NUM> of Example, Compound <NUM> of Example and methanol (solvent) were first added. After incubated for different periods (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>), 20µL of aggregation inducer <NUM> ADP solution was added. The aggregation rate of each sample was measured, and the inhibitory rate of the compound on ADP-induced platelet aggregation was calculated.

From the results (shown in <FIG>), it can be seen that the additions of PGE1 and Compound <NUM> of Example to PRP take effect immediately, and the inhibition rates were equivalent. With prolonged incubation time, the anticoagulant efficacy of the compound of the Example slowly decreased, and the inhibition rate is still <NUM>% after <NUM> minutes, but the inhibition rate of PGE1 is only <NUM>% after <NUM> minutes of incubation. Compound <NUM> of Example does not take effect immediately after the addition, and the efficacy gradually increased over time, and reaches the maximum inhibition rate of <NUM>% after <NUM> minutes of incubation. Therefore, Compound <NUM> of Example is an active non-prodrug compound, and its anticoagulant effect is <NUM> times longer than that of PGE1, and Compound <NUM> of Example is a typical prodrug compound.

In the experiment, rabbits were selected to prepare isolated aortic ring specimens: New Zealand white rabbits, male, weighing (<NUM>±<NUM>) kg. The rabbit was stunned with a blunt instrument, fixed on the rabbit dissecting table, and the thoracic aorta was quickly separated, and placed in a petri dish filled with saturated Kerbs solution (containing NaCl <NUM>, KCl <NUM>, MgSO<NUM>·<NUM><NUM>O <NUM>, KH<NUM>PO<NUM> <NUM>, NaHCO<NUM> <NUM>, CaCl<NUM> <NUM>, glucose <NUM> per <NUM>) at <NUM> and continuously introduced with mixed gas (<NUM>% O<NUM>, <NUM>% CO<NUM>). The remaining blood in the blood vessel was squeezed out, and the peripheral fat and connective tissue were carefully peeled off, and it was cut into <NUM> long arterial rings for use. Two stainless steel L-shaped hooks were used to pierce through the vascular lumen of the vascular ring, and the vascular ring was hung horizontally in a <NUM> bath tube, fixed at the bottom, and connected to a tension transducer with a thin steel wire at the top. The resting tension was first adjusted to <NUM>, and after stabilization for <NUM> minutes, <NUM> tension was applied, and the tension level was continuously adjusted to maintain it at about <NUM> and stabilized for <NUM> (replacing the Kerbs solution along the wall of the bath every <NUM> minutes).

BL-<NUM> biological function experiment system (Chengdu Techman Technology) was used to record the variation of vascular ring tension. After the vascular ring contraction was stable, prostaglandin E1 and the compounds of the Examples were accumulatively added to successively increase the final mass concentration of prostaglandin E1 in the bath tube to <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, and the diastolic efficacies of the vascular ring were recorded.

The results (shown in <FIG>) show that under the experimental conditions, the diastolic efficacy of the compound of Example <NUM> on isolated rabbit blood vessels (EC<NUM>=<NUM>) is significantly stronger than that of PGE1 (EC<NUM>=<NUM>).

Rats were anesthetized with <NUM>% sodium pentobarbital <NUM>/kg ip, fixed in the dorsal position, a <NUM> to <NUM> long incision was made in the midline of the abdomen, a section of small mesentery was gently pulled back to the cecum, and placed in an organic glass constant temperature water bath filled with physiological saline at <NUM>. The mesentery was kept moist and laid flat on the organic convex observation table in the center of the bath, and pressed with a fixing plate. The video image under the microscope was collected by the camera of the biological microscope (magnification <NUM> X), and the BI-<NUM> microcirculation observation system was used to real-time analyze the collected video images under the microscope.

A visual field was fixed and balanced for <NUM> minutes, and then the diameter and flow velocity of arterioles and venules in the selected area were observed. Then, <NUM>µL of a <NUM>:<NUM> diluted epinephrine hydrochloride physiological saline solution was added dropwise into the selected area, and an equal volume of physiological saline was added in the normal control group. At the same time, <NUM>µg/kg of the preparation of Example and Udil were immediately administered via the tail vein. The diameters of mesenteric arterioles were measured at <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM> after administration.

As shown in <FIG>, by measuring the diameter, the preparation group of Example <NUM> can significantly improve the microcirculation disorder caused by epinephrine, and there were significant differences between the preparation group of Example <NUM> and the model group from <NUM> to <NUM> minutes after administration (P<<NUM>). Compared with the model control group, the Udil group had no significant difference (P><NUM>) at <NUM>. The efficiency of improving microcirculation disorder caused by epinephrine in the Example group was significantly higher than that of Udil, and there was a significant difference between the two at <NUM>-<NUM> (P<<NUM>).

Sample processing method: the lyophilized emulsion of each Example was added with <NUM> for reconstitution, and one part was simultaneously diluted <NUM> times with water, and an appropriate amount was accurately metered and placed in a <NUM> brown test tube with a stopper. <NUM> of tetrahydrofuran was added, mixed well, and <NUM> of phosphoric acid solution (<NUM>→<NUM>) was added, mixed well and passed through the pretreatment column [the filler was ODS with a particle size of <NUM>, ϕ10mm×<NUM> polypropylene tube (SEP-PAK C18 column, Waters), rinsed with <NUM> of methanol and <NUM> of water before use]. The test tube was rinsed with <NUM> of water and passed through the pretreatment column. Then <NUM> methanol was used for elution, and all the eluate was transferred into a <NUM> brown distillation flask and distilled under reduced pressure at <NUM> for <NUM> minutes. The solvent was evaporated, and the residue was dissolved with <NUM> internal standard solution and shaken well to obtain the sample.

The ODS was used as a filler, <NUM>. 0067mol/L phosphate buffer (pH =<NUM>) (<NUM> of potassium dihydrogen phosphate was taken, and water was added to dissolve it to make <NUM> solution; <NUM> of anhydrous disodium hydrogen phosphate was separately taken, and water was added to dissolve it to make <NUM> solution; the latter was added to the former until the pH was <NUM>, <NUM> of this solution was taken and water was added to reach <NUM>, and shaken well to get the buffer)-acetonitrile (<NUM>:<NUM>) was used as a mobile phase. The flow rate was <NUM> per minute; the post-column reaction solution was 1mol·L-<NUM> KOH solution, and the post-column reaction tube was a polytetrafluoroethylene tube (φ0. <NUM>×<NUM>); column temperature was <NUM>; detection wavelength was <NUM>. <NUM>µl of each test substance and reference substance solution were injected, and calculated according to the internal standard peak area method.

Examples <NUM> to <NUM> and Udil were reconstituted with physiological saline to reach a concentration of <NUM>µg/mL, and all samples were diluted <NUM> times to <NUM>µg/mL, and appropriate amounts of the above-mentioned reconstituted preparations were taken and placed in an ultrafiltration centrifuge tube. After centrifugal ultrafiltration at <NUM> rpm for <NUM> minutes, <NUM> of the filtrate was taken to prepare a sample solution according to the above sample processing method, and <NUM>µl of sample was injected. The measured content of each drug is the free drug content.

Meanwhile, the free rates of <NUM> of reconstituted emulsion (<NUM>×) and <NUM>-fold dilution (<NUM>×) of the samples of each Example were measured.

The measured free rate of each example is shown in Table <NUM> below:.

The experimental results show that the free drug of Examples <NUM>-<NUM> was significantly lower than that of Udil after reconstitution. When Udil was diluted by <NUM> times according to the instructions, the free rate increased significantly. However, there was no significant increase in the free drug of the preparations prepared in the Examples of the disclosure.

Twenty New Zealand white rabbits were selected and divided into <NUM> groups with a weight of about <NUM>. Both the preparations of the Examples and Udil were reconstituted with physiological saline to reach <NUM>µg/ml, and further diluted with physiological saline to <NUM>µg/ml. According to the clinical dosage of prostaglandin E1, <NUM>. 5µg/kg was instilled slowly in the ear vein, and the same volume of physiological saline was injected in the ear vein at the opposite side, once a day for <NUM> days. Two hours after the last administration, the degree of vascular irritation was visually evaluated. All animals were sacrificed, and then the injection site was taken for histopathological examination. The results are shown in Table <NUM> and Table <NUM> below.

The results showed that the Example group was substantially non-irritative (P><NUM>), while the Udil group had obvious vascular irritation (P<<NUM>).

The appearance and particle size of the samples prepared in Examples <NUM> to <NUM> and Comparative Examples <NUM> and <NUM> are shown in Table <NUM> below:.

380ZLS particle size analyzer (dynamic light scattering method) from PSS corporation was used to determine the average particle size, and the Accusizer <NUM> instrument (light blockage method) from PSS corporation was used to determine the large-size emulsion droplets, and the percentage of emulsion droplets larger than <NUM> was calculated. The results showed that the samples prepared in Examples <NUM>-<NUM> had a good appearance after lyophilization, an average particle size after reconstitution significantly smaller than that of Comparative Example <NUM>, and a percentage of large emulsion droplets (><NUM>) much less than <NUM>%, while the large particle size (><NUM>) of Comparative Example <NUM> exceeds the standard (><NUM>%, USP standard), and Comparative Example <NUM> cannot be lyophilized.

The samples prepared in Examples <NUM>, <NUM>, <NUM>, and <NUM> were taken for a <NUM>-month long-term stability test (temperature <NUM>±<NUM>, humidity <NUM>%±<NUM>%). The results are shown in Table <NUM> below:.

The results showed that the lyophilized preparations of prostaglandin E1 methyl ester prepared in the Examples of the disclosure had stable product quality in the <NUM>-month long-term stability test.

In the pharmacokinetic experiment, <NUM> male SD rats were used in each group, fasted for <NUM> hours before administration, and given free drinking water. The two preparations were administered intravenously at a dose of <NUM>µg/kg respectively, and blood was collected from the orbit at <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, and <NUM> after administration. The blood concentration (the sum of prostaglandin E1 methyl ester and prostaglandin) measured at each time point is shown in <FIG>.

The pharmacokinetic parameters of the two preparations were calculated according to the blood concentration curve, the peak blood concentration after administration of Example <NUM> was significantly higher than that of Comparative Example <NUM>, the half-life was significantly prolonged, and the bioavailability was also significantly improved (see Table <NUM>).

Claim 1:
A method for producing a lyophilized preparation of prostaglandin E1 methyl ester for injection, wherein the method includes producing the lyophilized preparation with the following components as raw materials in weight percentage: <NUM>-<NUM>% of prostaglandin E1 methyl ester, <NUM>-<NUM>% of an oil for injection, <NUM>-<NUM>% of an emulsifier, <NUM>-<NUM>% of a co-emulsifier, <NUM>-<NUM>% of a lyoprotectant, <NUM>-<NUM>% of glycerin, an appropriate amount of pH adjuster, and a balance of water for injection;
wherein the method includes the following steps:
a. dispersing prostaglandin E1 methyl ester and <NUM>/<NUM> of the emulsifier uniformly in an oily solvent as an oil phase;
b. dissolving glycerin and the lyoprotectant and the remaining emulsifier in an appropriate amount of water for injection as a water phase, and adjusting the pH of the water phase to <NUM>-<NUM> with a pH regulator;
c. dissolving the co-emulsifier in the oil or water phase;
d. adding the oil phase to the water phase under stirring, or adding the water phase to the oil phase under stirring, and obtaining an initial emulsion by shearing, then diluting to full volume with water for injection;
e. homogenizing the initial emulsion to obtain a uniform emulsion;
f. sterilizing the obtained emulsion by filtration, packing, lyophilizing, and sealing to obtain the lyophilized preparation.