- Hand molding method: Cocoa butter is grated into small pieces. The drug is triturated into a very fine powder in a mortar. The drug and a portion of the cocoa butter are mixed with few drops of vegetable oil. The remaining cocoa butter is added by geometric dilution and triturated with pressure. The heat generated by trituration results in a plastic mass with cohesive property. The mass is scrapped from the mortar with a spatula and rolled into a ball. An ointment tile or slab is taken and dusted lightly with starch powder; the ball is placed on it and rolled with a flat-faced spatula to form a cylindrical mass. The cylinder is cut into desired number of pieces with a sharp blade. One end of the suppository is held firmly with a finger and the other end is tapered with the spatula to give the shape of suppository.
- Compression molding: In this method, compression mold instrument is used. This is especially suitable for thermolabile drugs. The drug is finely powdered and mixed intimately with the grated cocoa butter. The mixture is filled into a chilled cylinder. The mixture is pressed within the die cavity of the cylinder by a piston until a pressure is felt. Then, the formed suppositories are ejected from the other end of the cylinder.
- Pour molding (Fusion method): This is the mostly widely used method of preparing suppositories. A weighed quantity of the drug is powdered in a mortar. Carefully grated cocoa butter is taken into a china dish and heated in a water bath. When two-thirds of the portion is melted, the china dish is taken out of the heat source. The rest of the mass is melted by thorough stirring with a glass rod. The drug is incorporated into the china dish and stirred thoroughly to mix with the “creamy” base. The melted medicated base is then poured into previously lubricated mold. The mold is allowed to congeal and then placed on the ice bath for 30 minutes to harden. It is taken out and the surface is trimmed off with a sharp blade dipped in hot water. The mold is opened and the suppositories are expelled out by gentle pressure with the finger.
- Automatic molding machine: Large-scale batch process with high output ranging from 3500 to 6000 suppositories per hour can be carried out by using automatic molding machine. The manufacturing cycle process includes the following steps:
- The prepared mass is filled into a filling hopper where it is continuously mixed and maintained at constant temperature.
- The suppository molds are lightly lubricated by brushing or spraying a lubricant solution.
- The molten mass is filled into the molds to a slight excess.
- The mass is cooled to solidify and the excess material is scrapped off and collected for reuse.
- In the ejecting section, the mold is opened and the suppositories are gently pushed out by steel rods.
- The mold is closed and then moved to the initial step for the cycle process to continue.
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