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Microcapsules are formed by encapsulating a solid or liquid drug in a natural or synthetic polymeric material. The particle size of microcapsules is in the micron range, and those in the nanometer range are called nanocapsules, while the shape depends on the nature of the capsule core material and the way the capsule material coalesces. CD Formulation offers technologies for the microencapsulation of drugs, including many different preparation techniques, as well as techniques for the evaluation of the performance of drug microcapsules.
Fig.1 Schematic diagram of microcapsule degradation and emulsification process. (Lam et al., 2014)Aqueous phase separation method is to use water-soluble polymer material as wall material under certain action, the cohesive phase of polymer is separated from the aqueous solution to form microcapsules.
The oil phase separation method uses polymer organic solvents as the medium, and is based on adding a non-solvent liquid to the polymer organic solution containing the wall material or lowering the temperature to trigger phase separation to form microcapsules, and then curing and solvent removal to obtain the product.
Emulsion polymerization method is mainly used to prepare nano-microcapsules. In the presence of emulsifier in the dispersion medium, the drug and polymer monomers are dispersed to nano size using mechanical stirring or ultrasonic waves, and then the polymerization reaction is triggered and the formed polymer encapsulates the drug.
The ideal drug microcapsules require spherical shape, uniform size, good mobility and good dispersibility. The shape of microcapsules can be observed by microscopy and the particle size distribution can be determined by sedimentation method or Coulter's particle size analyzer.
The drug content is determined by solubilization method. When conducting the measurement, body fluids that simulate the human body environment, such as artificial gastric fluid or artificial intestinal fluid, are generally used as solvents to make the drug dissolve as much as possible while the wall material does not dissolve to determine the drug content.
The dissolution rate of the drug directly reflects the slow release and controlled release performance of the drug. There are many factors affecting the dissolution rate of drugs, such as the size of microcapsules, the thickness of the capsule wall, the content of drugs, the porosity of the capsule wall, etc.
Some drugs that are easily affected by temperature, pH, humidity or oxygen can be made into microencapsulated formulations to avoid the influence of light, oxygen and humidity to a certain extent, preventing drug decomposition and improving the chemical stability of drugs.
Some drugs have special odor, and making them into microencapsulated formulations can effectively cover up the bad odor of drugs, which is convenient for patients to take.
Some drugs are unstable in acid and can be destroyed by gastric acid. They are all easily inactivated in the gastrointestinal tract. Microencapsulation of these drugs improves the bioavailability of the drug while overcoming these defects.
The use of slow-release or controlled-release microencapsulated materials, after making the drug into microcapsules, can delay the release of the drug, prolong the drug action time, avoid blood concentration fluctuations to improve drug efficacy, reduce adverse reactions and achieve long-lasting effects.
The microencapsulation of liquid drug is beneficial to the process production of drug preparation, convenient for the technician to operate and reduce the production cost, and also increases the stability of the drug.
CD Formulation can provide you with technical support for drug microencapsulation and provide you with specific product solutions. If you are interested in our technology, please feel free to contact us.
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