Classification by route of administration
1. Tablets (coated tablets, matrix tablets, multi-layer tablets), pills, capsules (enteric-coated capsules, medicinal resin capsules, coated capsules) etc. administered through the gastrointestinal tract.
2. Parenteral administration of injections, suppositories, films, implants, etc.
According to different preparation techniques, sustained-release preparations can be divided into:
1. Skeleton-dispersed sustained-release preparations ①Water-soluble matrix, carboxymethylcellulose (CMC), hydroxypropylmethylcellulose (HPMC), polyvinylpyrrolidone (PVP), etc. are commonly used as matrix materials; ②Fat-soluble matrix, Fat and wax substances are commonly used as skeleton materials; ③ insoluble skeleton, insoluble non-toxic plastics are commonly used as skeleton materials.
2. Membrane-controlled sustained-release preparations commonly include film-coated sustained-release preparations and sustained-release microcapsules. The purpose of controlling the drug release rate is often achieved by controlling the thickness of the capsule, the diameter of the micropores, and the curvature of the micropores.
3. Sustained-release emulsions Water-soluble drugs can be made into W/O emulsions, because the oil has a certain barrier effect on the diffusion of drug molecules to achieve the purpose of sustained release.
4. Sustained-release preparations for injection are made of oil solution and suspension injections.
5. Sustained-release film preparations are sustained-release film preparations made by encapsulating drugs in polymer film compartments, or dissolving and dispersing them in polymer film sheets.