With the development and successful listing of several new oral membranes, this product has attracted wide attention at home and abroad since 2000. Membrane refers to the membranous preparation made by processing drugs and suitable film-forming materials. It has unique advantages when comparing with traditional preparations, such as simple producing technology and low cost; convenient administration and good patient compliance. Besides, orally soluble membrane can be taken without water, which is ideally suitable for the elders and children with dysphagia. It is easy to accurately divide the distributing doses compared with liquid preparation. The drugs are absorbed by oral mucosa, and directly enter systemic circulation through veins of sublingual mucosa, thus the first-pass effect can be avoided and bioavailability is higher. Therefore, oral membrane, as a new dosage form with good patient compliance, convenient portability and accurate dosage, has been successfully applied to prescription drugs, vitamins, health care products and oral drugs with low bioavailability, and has attracted wide attention as an alternative dosage form for traditional oral tablets, capsules, etc.
Preparation processes of oral membrane
The preparation processes of membrane include the common methods such as solvent casting method and hot melt extrusion method. Besides, there are semi-solid preparation, solid dispersion extrusion and spheronization method.
Solvent casting method: It is a common method for preparing membrane, which is suitable for preparing oral membrane containing thermo-sensitive prescription API. The membrane formation materials and auxiliary materials required for membrane-making are completely dissolved in organic solvents, pure water or the mixture of organic solvents and water to make uniform viscous liquid. Then the following steps shall be carried out: stir it with a high-speed mixer to form a viscous mixed aqueous solution, defoam and make it stand still for a while, spread the viscous solution on a mold or coat a filmogen, cut the membrane into target specifications after drying, and pack it in designated packages. The stability of API and its compatibility with auxiliary materials and solvents are the key factors affecting the process. For different API, we can select different types of membrane formation materials or make solid dispersions to ensure the stability of the final membrane.
Hot melt extrusion method: It is an important process for preparing membrane containing heat-insensitive API and auxiliary materials. It mainly includes the following steps: heat and homogenize the medicine, filmogen and other auxiliary materials until they are melted, mix and extrude them into a desired membrane shape through a mold, and finally get the thin membrane cooled down, cut and pack as the required membrane. This method has better content uniformity than the solvent casting method, and it does not need liquid solvent. The production process is simpler because it avoids the process of dissolution and homogenization. There is less material loss. In addition, the fine particles and insoluble drugs can be dispersed more evenly due to strong mixing and stirring in the preparation process. What's more, the adding of proper plasticizer can reduce the ductility of the membrane and improve the flexibility and anti-elongation of the product. The preparation process has good parameter control and the drug waste is minimized.
Application of oral membrane
China is the first country to include membrane in pharmacopoeia and put it on product application. The research on membrane in China start from the development of contraceptive medical membrane in 1970. The 1985 edition of Chinese Pharmacopoeia included membrane varieties, and the 1990 edition included general rules of the membrane. The 2020 edition of Chinese Pharmacopoeia defined membrane as: a membranous preparation made from raw medicines and membrane formation materials for use of oral administration or mucous membrane. The included membranes involve nonoxinol pellicles, clotrimazole pellicles, halcinonide membrane and compound norethindrone membrane. The general rules of preparation stipulate the appearance, packaging, weight difference and microorganism limitation of membrane. In 2012, the European Pharmacopoeia edit...
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