Injection Nano Drug Delivery System 1
Injection administration is to inject drugs into the body through injection to achieve the purpose of preventing and treating diseases. There are three ways of injection administration: intravenous (IV), intramuscular (IM) and subcutaneous (SC). Each has its own advantages and disadvantages. Different injection methods should be selected according to the specific situation.
Liposomes are vesicles sealed by a bilayer of phospholipids, similar to the cell structure, with an internal aqueous phase that can encapsulate water-soluble drugs. The inside of the lipid bilayer is fat-soluble and can encapsulate fat-soluble drugs, but the capacity is limited. According to the particle size, liposomes can be divided into small unilamellar vesicles (SUV, 30~100nm), large unilamellar vesicles (LUV, 100~250nm), if it is a multilayer membrane, it can be called multilamellar liposomes vesicles (MLV). Liposomes are mainly composed of phospholipids, but in order to improve performance, different lipid molecules such as cholesterol and cationic lipids can be added. Many drugs require a certain period of time to reach and maintain the blood concentration to obtain the best effect. The half-life of intravenous, subcutaneous and intramuscular injection is very short, usually between 1 hour and several hours. The therapeutic concentration of the drug can only be maintained through frequent and multiple administrations, but the cost of the treatment plan is high, the patient’s compliance is poor, and it is easy to cause adverse reactions.
Intravenous injection is a common way of administration of liposomes. Liposomes are quickly eliminated from the blood circulation after intravenous injection. The elimination rate is related to the size of the liposomes and the charge on the surface. Large liposomes are eliminated faster than small ones. Intravenously injected liposomes are preferentially taken up by reticuloendothelial tissues such as liver and spleen, and are rapidly engulfed and degraded by mononuclear phagocytes, and small amounts are taken up by lung, bone marrow and kidney. Utilizing the characteristics of liposomes passively targeting the reticuloendothelial system (RES, also called mononuclear macrophage system, MPS) in the blood circulation, the contained drugs or immunomodulators can be released into the reticuloendothelial system to kill the parasites whose growth cycle is related to the reticuloendothelial system. Liposome intravenous injection can exert a sustained-release function. For example, actinomycin D is quickly eliminated from the blood circulation within a few minutes after intravenous injection. After liposome encapsulation, 45% to 50% of the drug still exerts efficacy after 3 hours. Intravenous injection of liposomes can be used to treat systemic fungal infections, bacterial infections, cancers, etc. In addition, the multivesicular liposomes (MVL) prepared by the reservoir foam technology can be injected and administered by various routes such as intrathecal, subcutaneous and intramuscular. It is characterized by large particle size, can accumulate in a large amount in the injection site or the administration chamber, has a slow-release effect and a storage effect, can effectively reduce the number of patient medications, and improve treatment compliance. Amikacin sulfate MVL preparations can be used to treat soft tissue infections sensitive to amikacin. After subcutaneous injection of this product in animals, the slow release time of the drug is 7-10 days, which can effectively treat local infections in rats and reduce the systemic blood concentration.
Microemulsion and Nanoemulsion
The particle size of microemulsion is between 10~100nm. It is a stable, transparent, low viscosity, homogeneous and thermodynamically stable formed by oil phase, water phase, surfactant and co-surfactant in appropriate proportions. As long as the composition of the four phases is appropriate, the dispersion system can form a uniform and transparent or slightly opalescent liquid, which is a thermodynamically stable system. Nanoemulsion (Nanoemulsion) particle size is between 20~200nm, its particle size is more suitable for drug loading and targeting. Nanoemulsions have received widespread attention in recent years due to their significant targeting, sustained-release effects and strong solubilization effects on poorly soluble drugs.
Nanoemulsion as a drug carrier has the following characteristics: 1, It has the characteristics of solubilization and sensitization; 2, It has the characteristics of simple preparation and good physical stability, and can be sterilized; 3, It can simultaneously contain different fat-soluble drugs to improve certain Stabilize the stability of drugs; 4, It increases the bioavailability of macromolecular drugs; 5, It increases the solubility of poorly soluble drugs; 6, It as a transparent liquid with the same properties, thermodynamically stable and filterable, easy to prepare and store; 7, It has low viscosity, when injected It will not cause pain; 8, The nanoemulsion has a small and uniform particle size, which can improve the dispersion of the encapsulated drug, and has a protective effect on the easily hydrolyzed drug after being made into a water-in-oil nanoemulsion; 9, Slow-release and targeting effects. Therefore, the use of nanoemulsion as a carrier for injection administration is also a good choice.