Pellets refer to small spherical oral dosage forms having a diameter of less than 2.5 mm. The sustained-release and controlled-release pellets prepared by mixing the medicine with a retarder or the like, or firstly forming a pellet core and then controlling the release film coating, are dose-dispersed preparations, and the primary dose is composed of a plurality of units. There are many advantages over single dosage forms. It can increase the contact area between the drug and the gastrointestinal tract, so that the drug can be completely absorbed, thereby improving the bioavailability; through a combination of pellets of different release rates, the desired release rate can be obtained, and the expected blood concentration can be obtained. It can maintain a long duration of action and avoid adverse reactions such as irritation to the gastric mucosa; its release behavior is the sum of the release behavior of multiple pellets constituting one dose, and the defects in the preparation of individual pellets are not released to the entire preparation. Behavior has a serious impact, so its drug release law is reproducible; drugs in the body are rarely affected by changes in gastric emptying function, absorption in the body has good reproducibility; can be made up of different drugs can be made into pellets Can increase the stability of the drug. Moreover, it is also convenient for quality control; making pellets can change certain properties of the drug, such as good fluidity and non-breaking after pelleting, and can be used as a basis for preparing tablets, capsules, etc.; Position the formulation. Therefore, slow-release and controlled-release pellets are currently considered to be one of the ideal slow-release and controlled-release dosage forms, and are the current development direction of slow-release and controlled-release preparations.
1 Types and preparation methods of slow and controlled release pellets
1.1 Types of slow and controlled release Xiaojiu
2. The slow and controlled release pellets are different in composition and structure. There are generally three types of membrane-controlled pellets, skeleton pellets, and pellets combined with a membrane and membrane control method. The membrane-controlled pellets are first made into a pellet core, and then wrapped in a controlled release coating and a pellet core in addition to the drug, and further contain a diluent, a binder and the like. The coating material is some high molecular polymer, most of which are Hard to dissolve in water or insoluble in water. The coating liquid is in addition to the coating material. Generally, plasticizers, porogens, colorants, anti-adherents, etc. are added or not, thereby controlling the drug release rate. Skeleton pellets are pellets made by mixing a drug with a retarder. The pellets prepared by the combination of the skeleton and the membrane control method are further coated on the basis of the skeleton pellets, thereby obtaining a better slow and controlled release effect.
1.2 Preparation method
1.2.1 Forming technology of pellets The molding method of pellets is directly formed into spherical pellets by a multi-extrusion molding machine and a spherical molding machine; pellets are formed by rolling coalescence and rotary granulation by a coating pan and a rotary granulator; The pellets are prepared by spray coagulation in a dryer, a bubbling bed drying system, etc.; the pellets are prepared by stirring at a high speed in a liquid medium; and the pellets are prepared by a micro-forming technique by means of a vibration spray. Which method is used to mix the drug and the auxiliary material evenly. It is made into a drug pellet with good roundness, suitable hardness, narrow particle size distribution and good fluidity.
The coating pan is rolled into a pill method, which is further divided into a rolling pan-pill method, in which a mixed powder of a drug and an auxiliary material is placed in a coating pan, a wetting agent or a binder (water, a dilute alcohol, etc.) is sprayed, and rolled into a pill. Such as the preparation of captopril controlled release pellets. The wet granules are rolled into pellets, and the drug and the auxiliary powder are mixed, and the binder is added into a soft material, and the granules are sieved and granulated, and the wet granules are rolled in a coating pan for a certain time, and dried to obtain pellets. Such as the preparation of theophylline sustained release pellets and the like. In order to improve the roundness, a liquid binder or a wetting agent can be sprayed on the basis, and a mixed powder of the drug or the drug and the auxiliary material can be sprinkled, and the operation is repeated to prepare a pellet having a suitable size and a good roundness. . Such as the preparation of diclofenac controlled release pellets. The blank pellet core ball method, that is, using a spherical blank pellet core as a seed, placed in a coating pan, sprayed into a suitable binder solution, sprinkled into a powder of medicine or a mixed powder of a drug and an auxiliary material, and rolled into a pellet; The drug is dissolved or suspended in the solution, and sprayed on the pellet core to form a pellet. Because the drug loading is small, the dosage is generally about 50%, and it is suitable for pelleting a small dose of the drug.
There are many factors affecting the roundness of the pellets, including the nature of the drug powder; the type and amount of excipients and binders; the temperature and humidity of the environment; the amount of one input of the material; the coating The shape and rotation speed of the pot; the shape of the mother core. The coated pan-pill has the disadvantages of high labor intensity, large dust pollution, low yield of finished products, low drying rate, and poor reproducibility between batches.
Extrusion granulation-spheronization method, the equipment includes two parts of the extrusion device and the spheronization device. The medicine and the auxiliary materials are uniformly mixed into water, alcohol or a binder solution to form a soft material; then the wet material is passed through a hole or sieve having a certain pore diameter by a suitable extruder to prepare cylindrical particles and strip extrusion. The object is then rounded into a pellet by a rounding machine. The spheronizer formed by the extruder of the extruder can also be splayed by a frictional force by a friction plate which is mainly rotated at a certain rate. This is the current method of applying Zui Guang.
The centrifugal method is used to create a round and uniform pellet by using a centrifugal granulator to complete the mixing, demoulding, culling, drying and coating processes in a closed system. The host of centrifugal granulation is a centrifuge with fluidization at the same time. During the pelleting, the mixed fine powder or mother nucleus of some drugs and auxiliary materials can be directly put into the fluidized bed of the centrifuge and blasted. The powder is in centrifugal force and Under the effect of friction. Forming a vortex-to-rotation particle flow on the curved surface of the stator and the rotor, so that the particles can be tumbling and evenly stirred, and an appropriate amount of atomized slurry is sprayed through the spray gun, and the powder is condensed into granules to obtain a spherical core, and then continue to be sprayed. 3. The atomized slurry well sprays the powder containing the powder. Increase the mother nucleus into pills. After the pellets are dry. Spray the appropriate coating liquid into the atomization to make the surface of the pellet coated with a certain thickness of the cloth, that is, the membrane-controlled pellets. This method has a fast pelleting speed. The pellets have a high degree of sphericity, a small powder stick, saving time and effort. For example, the preparation of diltiazem hydrochloride controlled release pellets.
Fluidized bed pelleting method consists of an air compression system, a power heating system, a spray system and a control system. The method comprises the steps of placing the material in the fluidization chamber, and the air of a certain temperature enters the fluidization chamber from the bottom through the screen, so that the medicine and the auxiliary material are suspended and mixed in the fluidization chamber, and then sprayed into the atomized binder, and the powder begins to coalesce into Uniform pellets, when the particle size reaches the specified requirements, stop spraying and the formed particles are directly dried in the fluidization chamber. The coating of the pellets is also carried out in the fluidized bed, and since the pellets are in a fluidized state, the blocking phenomenon can be effectively prevented. The method has the advantages of complete mixing, granulating, drying and coating in a closed system; the obtained pellets are uniform in size, narrow in particle size distribution, round in shape and free from adhesion; the fluidized bed is provided with a powder recovery device. , the original accessories are not lost. The organic solvent of the coating liquid can also be recovered, which is advantageous for improvement of the operating environment and reduction of production cost.
The spherical forming mechanism is a pellet method in which a mixture of a drug and an auxiliary material is added to a binder, a soft material is produced, and granulated by a sieve, and the prepared wet granules are put into a spherical molding machine and rolled into pellets at a high speed, followed by drying.
The liquid medium is used to prepare pellets, and the pellets prepared by the medicine and the auxiliary materials are stirred in a liquid medium to form pellets. Kim et al. prepared the microbial C pellets in a liquid medium, and the obtained pellets had good sphericity and a narrow particle size distribution.
The vibrating nozzle micro-forming technique produces pellets, and Jedrass et al. prepares the pellets by dropping the molten pellet core into a cooling liquid through a vibrating nozzle. The formation of the pellet core depends directly on the diameter of the vibrating nozzle, the frequency and amplitude of the vibration. The solubility, density and melting point of the core material must be taken into account when using this method. The material for preparing the pellet core must be solid at room temperature, liquid after heating, and the formed droplets are insoluble and non-diffusing in the cooling liquid, and the density of the pellet core should be greater than the density of the coolant when molten and solid.
The spherical aggregation technique of the drug in the liquid phase causes the drug to agglomerate while being crystallized in a suitable solvent to form a granule or pellet. The key to this method is to choose the type and proportion of the solvent system. The drug concentration, operating temperature and stirring speed also affect the quality of the formulation. Such as aspirin aggregation particles, aspirin pellets and isosorbide dinitrate (xiaoxintong) pellets.
Spray drying method and spray freezing method, the former is spray drying the drug solution or suspension, and the mountain is evaporated in the liquid phase to form a pellet. The latter is to mix the drug with molten fat or wax from the top into a cooling tower, since the droplets are hardened by cold to form pellets. The pellets obtained by the above method are small, only a few to several tens of micrometers; and are porous.
There are various methods and devices for preparing pellets, each having its own advantages and disadvantages. In the selection, it should be based on the characteristics of the drug and auxiliary materials, product requirements, batch size and actual conditions, and reasonable choice.
1.2.2 The coating technology support and controlled release pellets of the pellets not only improve the appearance, taste, and increase the stability of the drug, but also achieve the purpose of improving the biopharmaceutical properties of the drug. The coating of the pellets can be carried out in a coating pan or a high-efficiency coating pan, or in an air suspension fluidized bed coating method in a centrifugal granulator, in a fluidized bed, or in a coating liquid. Coating and other methods.
Because the common coating pan coating has the disadvantages of low drying efficiency, large dust pollution, batch difference and long operation time, it is more in the improved coating pan such as the baffle coating pan and the buried tube spray bag. In the clothes pot. The buried spray coating pan is particularly suitable for coating with a water-decomposing body as a coating liquid, which can greatly shorten the coating time.
The air suspension fluid bed coating suspends the pellet in the coating chamber by means of a rapidly rising air flow, so that it is in a non-stop flow state, and sprays the coating solution or suspension into the pellet surface, that is, on the surface of the pellet. And the hot air stream is dried and repeatedly coated until the weight is increased to the desired thickness. The fluidized bed type has a fluidized bed for top spray granulation and coating, a bottom spray coating fluidized bed and a rotary fluidized bed. The key factors affecting the properties of the film during fluidized bed coating are the film temperature and the gun pressure, in addition to the amount of polymer. This method is a very effective slow release coating method, such as fluidized bed cutting. The pellets were prepared by coating.
The immersion coating system spreads the pellets evenly on the sieve mesh, quickly passes through the coating liquid, and is dried together with the sieve mesh, gently flipped, and then quickly passed through the coating liquid. Repeatedly. The specified requirements have been met.
2 pellets accessories
2.1 blank pellet core
A granule such as 30 to 40 mesh sucrose fine granules or granulated sugar powder and starch which is rolled with a suitable binder is used as a pellet core which is rolled into pellets. There is a spherical blank pill core with a non-areil name in foreign countries. There are also commodity supplies in China.
2.2 Coating accessories
The coating materials are basically the same as the slow and controlled release tablets. The coating liquid generally includes a film-forming material, a plasticizer, or a porogen, a colorant, an anti-adhesive agent, an antifoaming agent, a light-protecting agent, and a solvent or a dispersion medium.
2.3 skeleton pellets accessories
Generally, there are retarders, porogens, surfactants, and the like. Blockers are generally classified as insoluble (such as ethyl cellulose, ethylene-vinyl acetate copolymer, etc.), biosoluble (such as stearic acid, stearyl alcohol, glyceryl monostearate, etc.) and hydrophilic gels (such as Sodium alginate, hydroxypropyl methylcellulose, etc.) three major types of framework materials. A mixture of one or more types of materials may be selected to be mixed with the drug and made by a suitable method. In order to adjust the drug release rate, a porogen or a surfactant may be added.
3 pellet release mechanism
Due to the difference in the pellet core, the film material or the skeleton material constituting the child, there may be various drug release mechanisms for the release of the drug from the pellet, and the following are summarized.
3.1 Coating film formed by hydrophilic polymer
In the case of digestive juice, the film coat swells, forming a gel barrier to control the dissolution of the drug, and is rarely affected by changes in gastrointestinal physiological factors and pH.
3.2 Insoluble film clothing
There are molecular size pores between the crosslinked polymer chains on the coated polymer film, the drug molecules are dissolved, and the partitioning process enters and diffuses through these pores. If the pellet core is composed of hypertonic substances, the osmotic pressure difference generated inside and outside the membrane The role of drug delivery is also very important.
3.3 Adding a sustained release film of porogen
Some osmotic slow, controlled release materials such as cellulose acetate, ethyl cellulose and non-permeable material silicone elastomers are used to form a closed film. In the coating liquid, some water-soluble substances or insoluble solid ingredients are often added. To act as a porogen. When the film is in contact with water, the porogen dissolves or falls off, causing the film to form a microporous or sponge-like structure, and the water thus penetrates into the core of the human body to dissolve and release the drug.
3.4 Plasticizer hole release
When the plasticizer is unevenly dispersed in the coating film and the content is high, the plasticizer may form a channel in the film and become a continuous phase in the channel. If the solubility in the drug plasticizer is greater than the solubility in water, the drug may be preferentially released through this channel.
3.5 Release of the skeleton pellets
The hydrophilic gel skeleton pellets are in contact with water to form a viscous gel layer, and the drug diffuses and releases through the gel layer, and the release mechanism mainly includes skeleton dissolution and drug diffusion. Pellets made of waxy or other polymer materials, waxy, etc. can be dissolved by gastrointestinal fluids and dispersed into small particles, thereby releasing the contained drugs. The release mechanism is the abrasion-dispersion-dissolution of the outer surface. process.
4 Research progress of Chinese medicine pellets
Due to the backward technological conditions such as pelleting and drying, the bolus lacks pores and capillaries, which is difficult to disintegrate and has low bioavailability. Chinese medicine pellets have advantages in increasing the contact area between drugs and body fluids and improving bioavailability. At present, there are some research reports on Chinese medicine pellets, such as the preparation of series of pellets by plastic method, the preparation of Niupo Zhibao pellets by general method, the preparation of Qingfei Zhike Pingchuan pellets by solid dispersion technique, and the preparation of Liushenjiu and marine stomach medicine by centrifugal granulation. The pellets and the Gynostemma pentaphyllum pellets, and the acrylic resin IV coating to prepare the Jinqi Dingtong pellets and the like. However, studies on slow-release and controlled-release pellets of Chinese medicine have not been reported.
Due to the characteristics of the dosage forms, the pellets have attracted the attention of pharmaceutical workers at home and abroad. The research on slow and controlled release pellets has been widely carried out. According to the principles of diffusion, dissolution and osmotic pressure, the process of coating and making pellet pellets can be designed and controlled to control the dissolution of the drug to obtain the ideal release rate. With the development of pelleting technology, coating technology, pelletizing equipment and polymer materials, the research on slow and controlled release Xiaojiu will surely achieve greater development.
1 Types and preparation methods of slow and controlled release pellets
1.1 Types of slow and controlled release Xiaojiu
2. The slow and controlled release pellets are different in composition and structure. There are generally three types of membrane-controlled pellets, skeleton pellets, and pellets combined with a membrane and membrane control method. The membrane-controlled pellets are first made into a pellet core, and then wrapped in a controlled release coating and a pellet core in addition to the drug, and further contain a diluent, a binder and the like. The coating material is some high molecular polymer, most of which are Hard to dissolve in water or insoluble in water. The coating liquid is in addition to the coating material. Generally, plasticizers, porogens, colorants, anti-adherents, etc. are added or not, thereby controlling the drug release rate. Skeleton pellets are pellets made by mixing a drug with a retarder. The pellets prepared by the combination of the skeleton and the membrane control method are further coated on the basis of the skeleton pellets, thereby obtaining a better slow and controlled release effect.
1.2 Preparation method
1.2.1 Forming technology of pellets The molding method of pellets is directly formed into spherical pellets by a multi-extrusion molding machine and a spherical molding machine; pellets are formed by rolling coalescence and rotary granulation by a coating pan and a rotary granulator; The pellets are prepared by spray coagulation in a dryer, a bubbling bed drying system, etc.; the pellets are prepared by stirring at a high speed in a liquid medium; and the pellets are prepared by a micro-forming technique by means of a vibration spray. Which method is used to mix the drug and the auxiliary material evenly. It is made into a drug pellet with good roundness, suitable hardness, narrow particle size distribution and good fluidity.
The coating pan is rolled into a pill method, which is further divided into a rolling pan-pill method, in which a mixed powder of a drug and an auxiliary material is placed in a coating pan, a wetting agent or a binder (water, a dilute alcohol, etc.) is sprayed, and rolled into a pill. Such as the preparation of captopril controlled release pellets. The wet granules are rolled into pellets, and the drug and the auxiliary powder are mixed, and the binder is added into a soft material, and the granules are sieved and granulated, and the wet granules are rolled in a coating pan for a certain time, and dried to obtain pellets. Such as the preparation of theophylline sustained release pellets and the like. In order to improve the roundness, a liquid binder or a wetting agent can be sprayed on the basis, and a mixed powder of the drug or the drug and the auxiliary material can be sprinkled, and the operation is repeated to prepare a pellet having a suitable size and a good roundness. . Such as the preparation of diclofenac controlled release pellets. The blank pellet core ball method, that is, using a spherical blank pellet core as a seed, placed in a coating pan, sprayed into a suitable binder solution, sprinkled into a powder of medicine or a mixed powder of a drug and an auxiliary material, and rolled into a pellet; The drug is dissolved or suspended in the solution, and sprayed on the pellet core to form a pellet. Because the drug loading is small, the dosage is generally about 50%, and it is suitable for pelleting a small dose of the drug.
There are many factors affecting the roundness of the pellets, including the nature of the drug powder; the type and amount of excipients and binders; the temperature and humidity of the environment; the amount of one input of the material; the coating The shape and rotation speed of the pot; the shape of the mother core. The coated pan-pill has the disadvantages of high labor intensity, large dust pollution, low yield of finished products, low drying rate, and poor reproducibility between batches.
Extrusion granulation-spheronization method, the equipment includes two parts of the extrusion device and the spheronization device. The medicine and the auxiliary materials are uniformly mixed into water, alcohol or a binder solution to form a soft material; then the wet material is passed through a hole or sieve having a certain pore diameter by a suitable extruder to prepare cylindrical particles and strip extrusion. The object is then rounded into a pellet by a rounding machine. The spheronizer formed by the extruder of the extruder can also be splayed by a frictional force by a friction plate which is mainly rotated at a certain rate. This is the current method of applying Zui Guang.
The centrifugal method is used to create a round and uniform pellet by using a centrifugal granulator to complete the mixing, demoulding, culling, drying and coating processes in a closed system. The host of centrifugal granulation is a centrifuge with fluidization at the same time. During the pelleting, the mixed fine powder or mother nucleus of some drugs and auxiliary materials can be directly put into the fluidized bed of the centrifuge and blasted. The powder is in centrifugal force and Under the effect of friction. Forming a vortex-to-rotation particle flow on the curved surface of the stator and the rotor, so that the particles can be tumbling and evenly stirred, and an appropriate amount of atomized slurry is sprayed through the spray gun, and the powder is condensed into granules to obtain a spherical core, and then continue to be sprayed. 3. The atomized slurry well sprays the powder containing the powder. Increase the mother nucleus into pills. After the pellets are dry. Spray the appropriate coating liquid into the atomization to make the surface of the pellet coated with a certain thickness of the cloth, that is, the membrane-controlled pellets. This method has a fast pelleting speed. The pellets have a high degree of sphericity, a small powder stick, saving time and effort. For example, the preparation of diltiazem hydrochloride controlled release pellets.
Fluidized bed pelleting method consists of an air compression system, a power heating system, a spray system and a control system. The method comprises the steps of placing the material in the fluidization chamber, and the air of a certain temperature enters the fluidization chamber from the bottom through the screen, so that the medicine and the auxiliary material are suspended and mixed in the fluidization chamber, and then sprayed into the atomized binder, and the powder begins to coalesce into Uniform pellets, when the particle size reaches the specified requirements, stop spraying and the formed particles are directly dried in the fluidization chamber. The coating of the pellets is also carried out in the fluidized bed, and since the pellets are in a fluidized state, the blocking phenomenon can be effectively prevented. The method has the advantages of complete mixing, granulating, drying and coating in a closed system; the obtained pellets are uniform in size, narrow in particle size distribution, round in shape and free from adhesion; the fluidized bed is provided with a powder recovery device. , the original accessories are not lost. The organic solvent of the coating liquid can also be recovered, which is advantageous for improvement of the operating environment and reduction of production cost.
The spherical forming mechanism is a pellet method in which a mixture of a drug and an auxiliary material is added to a binder, a soft material is produced, and granulated by a sieve, and the prepared wet granules are put into a spherical molding machine and rolled into pellets at a high speed, followed by drying.
The liquid medium is used to prepare pellets, and the pellets prepared by the medicine and the auxiliary materials are stirred in a liquid medium to form pellets. Kim et al. prepared the microbial C pellets in a liquid medium, and the obtained pellets had good sphericity and a narrow particle size distribution.
The vibrating nozzle micro-forming technique produces pellets, and Jedrass et al. prepares the pellets by dropping the molten pellet core into a cooling liquid through a vibrating nozzle. The formation of the pellet core depends directly on the diameter of the vibrating nozzle, the frequency and amplitude of the vibration. The solubility, density and melting point of the core material must be taken into account when using this method. The material for preparing the pellet core must be solid at room temperature, liquid after heating, and the formed droplets are insoluble and non-diffusing in the cooling liquid, and the density of the pellet core should be greater than the density of the coolant when molten and solid.
The spherical aggregation technique of the drug in the liquid phase causes the drug to agglomerate while being crystallized in a suitable solvent to form a granule or pellet. The key to this method is to choose the type and proportion of the solvent system. The drug concentration, operating temperature and stirring speed also affect the quality of the formulation. Such as aspirin aggregation particles, aspirin pellets and isosorbide dinitrate (xiaoxintong) pellets.
Spray drying method and spray freezing method, the former is spray drying the drug solution or suspension, and the mountain is evaporated in the liquid phase to form a pellet. The latter is to mix the drug with molten fat or wax from the top into a cooling tower, since the droplets are hardened by cold to form pellets. The pellets obtained by the above method are small, only a few to several tens of micrometers; and are porous.
There are various methods and devices for preparing pellets, each having its own advantages and disadvantages. In the selection, it should be based on the characteristics of the drug and auxiliary materials, product requirements, batch size and actual conditions, and reasonable choice.
1.2.2 The coating technology support and controlled release pellets of the pellets not only improve the appearance, taste, and increase the stability of the drug, but also achieve the purpose of improving the biopharmaceutical properties of the drug. The coating of the pellets can be carried out in a coating pan or a high-efficiency coating pan, or in an air suspension fluidized bed coating method in a centrifugal granulator, in a fluidized bed, or in a coating liquid. Coating and other methods.
Because the common coating pan coating has the disadvantages of low drying efficiency, large dust pollution, batch difference and long operation time, it is more in the improved coating pan such as the baffle coating pan and the buried tube spray bag. In the clothes pot. The buried spray coating pan is particularly suitable for coating with a water-decomposing body as a coating liquid, which can greatly shorten the coating time.
The air suspension fluid bed coating suspends the pellet in the coating chamber by means of a rapidly rising air flow, so that it is in a non-stop flow state, and sprays the coating solution or suspension into the pellet surface, that is, on the surface of the pellet. And the hot air stream is dried and repeatedly coated until the weight is increased to the desired thickness. The fluidized bed type has a fluidized bed for top spray granulation and coating, a bottom spray coating fluidized bed and a rotary fluidized bed. The key factors affecting the properties of the film during fluidized bed coating are the film temperature and the gun pressure, in addition to the amount of polymer. This method is a very effective slow release coating method, such as fluidized bed cutting. The pellets were prepared by coating.
The immersion coating system spreads the pellets evenly on the sieve mesh, quickly passes through the coating liquid, and is dried together with the sieve mesh, gently flipped, and then quickly passed through the coating liquid. Repeatedly. The specified requirements have been met.
2 pellets accessories
2.1 blank pellet core
A granule such as 30 to 40 mesh sucrose fine granules or granulated sugar powder and starch which is rolled with a suitable binder is used as a pellet core which is rolled into pellets. There is a spherical blank pill core with a non-areil name in foreign countries. There are also commodity supplies in China.
2.2 Coating accessories
The coating materials are basically the same as the slow and controlled release tablets. The coating liquid generally includes a film-forming material, a plasticizer, or a porogen, a colorant, an anti-adhesive agent, an antifoaming agent, a light-protecting agent, and a solvent or a dispersion medium.
2.3 skeleton pellets accessories
Generally, there are retarders, porogens, surfactants, and the like. Blockers are generally classified as insoluble (such as ethyl cellulose, ethylene-vinyl acetate copolymer, etc.), biosoluble (such as stearic acid, stearyl alcohol, glyceryl monostearate, etc.) and hydrophilic gels (such as Sodium alginate, hydroxypropyl methylcellulose, etc.) three major types of framework materials. A mixture of one or more types of materials may be selected to be mixed with the drug and made by a suitable method. In order to adjust the drug release rate, a porogen or a surfactant may be added.
3 pellet release mechanism
Due to the difference in the pellet core, the film material or the skeleton material constituting the child, there may be various drug release mechanisms for the release of the drug from the pellet, and the following are summarized.
3.1 Coating film formed by hydrophilic polymer
In the case of digestive juice, the film coat swells, forming a gel barrier to control the dissolution of the drug, and is rarely affected by changes in gastrointestinal physiological factors and pH.
3.2 Insoluble film clothing
There are molecular size pores between the crosslinked polymer chains on the coated polymer film, the drug molecules are dissolved, and the partitioning process enters and diffuses through these pores. If the pellet core is composed of hypertonic substances, the osmotic pressure difference generated inside and outside the membrane The role of drug delivery is also very important.
3.3 Adding a sustained release film of porogen
Some osmotic slow, controlled release materials such as cellulose acetate, ethyl cellulose and non-permeable material silicone elastomers are used to form a closed film. In the coating liquid, some water-soluble substances or insoluble solid ingredients are often added. To act as a porogen. When the film is in contact with water, the porogen dissolves or falls off, causing the film to form a microporous or sponge-like structure, and the water thus penetrates into the core of the human body to dissolve and release the drug.
3.4 Plasticizer hole release
When the plasticizer is unevenly dispersed in the coating film and the content is high, the plasticizer may form a channel in the film and become a continuous phase in the channel. If the solubility in the drug plasticizer is greater than the solubility in water, the drug may be preferentially released through this channel.
3.5 Release of the skeleton pellets
The hydrophilic gel skeleton pellets are in contact with water to form a viscous gel layer, and the drug diffuses and releases through the gel layer, and the release mechanism mainly includes skeleton dissolution and drug diffusion. Pellets made of waxy or other polymer materials, waxy, etc. can be dissolved by gastrointestinal fluids and dispersed into small particles, thereby releasing the contained drugs. The release mechanism is the abrasion-dispersion-dissolution of the outer surface. process.
4 Research progress of Chinese medicine pellets
Due to the backward technological conditions such as pelleting and drying, the bolus lacks pores and capillaries, which is difficult to disintegrate and has low bioavailability. Chinese medicine pellets have advantages in increasing the contact area between drugs and body fluids and improving bioavailability. At present, there are some research reports on Chinese medicine pellets, such as the preparation of series of pellets by plastic method, the preparation of Niupo Zhibao pellets by general method, the preparation of Qingfei Zhike Pingchuan pellets by solid dispersion technique, and the preparation of Liushenjiu and marine stomach medicine by centrifugal granulation. The pellets and the Gynostemma pentaphyllum pellets, and the acrylic resin IV coating to prepare the Jinqi Dingtong pellets and the like. However, studies on slow-release and controlled-release pellets of Chinese medicine have not been reported.
Due to the characteristics of the dosage forms, the pellets have attracted the attention of pharmaceutical workers at home and abroad. The research on slow and controlled release pellets has been widely carried out. According to the principles of diffusion, dissolution and osmotic pressure, the process of coating and making pellet pellets can be designed and controlled to control the dissolution of the drug to obtain the ideal release rate. With the development of pelleting technology, coating technology, pelletizing equipment and polymer materials, the research on slow and controlled release Xiaojiu will surely achieve greater development.
Natural Cranberry powder is the extract of cranberry fruit. Cranberry is a type of evergreen shrub that grows in wet areas, such as bogs or wetlands and is native to northeastern and northcentral parts of the United States. The shrub has small, dark green leaves, pink flowers, and dark red fruit that are egg-shaped. Cranberry is most commonly used for the prevention and treatment of urinary tract infections. In foods, cranberry fruit is used in cranberry juice, cranberry juice cocktail, jelly, and sauce.
The cranberry was primarily used as a traditional medicine for the treatment of bladder and kidney ailments among Native Americans. The berries were also used as a fabric and food dye, and as a poultice to treat wounds and blood poisoning. Sailors used the berries as a scurvy preventative. Despite a general lack of scientific evidence to indicate that cranberries or their juice are effective urinary acidifiers, interest persists among the public in the medicinal use of cranberries. Cranberries are used in eastern European cultures to reduce fever and, because of their folkloric role, in the treatment of cancers.
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