Hard gelatin capsules are widely used because * swallowing is very easy * elegant * the shells have no taste and the drugs which are not having pleasant taste and smell can be administered * they can be manufactured in different colors * the drug will be released easily as there is no compaction These are not generally used for the compounds that are highly soluble because the drug will be delivered all at once. Those materials which release the water causes softening of the capsules and the substances that absorb the water cause brittleness to the powder. So care must be taken while packing these kinds of the materials
. MATERIALS USED:
* Main constituent: gelatin * Other materials used: some plasticizers, dyes and preservatives. Properties of gelatin is based on * pH * the process through which gelatin is extracted * electrolytes present Gelatin is obtained from animal bones, frozen pork skin. Two type of gelatin are present Type A and type B. Generally mixtures of gelatins are used in the preparation of capsules. Gelatin obtained from the bone and porn skin is mixed and the gel having high strength is used for preparation of hard gelatin capsules.
Production process: The process of gelatin preparation involves the following steps: Dipping: the stainless steel mold pin is dipped in to the gelatin sol which has required viscocity. Spinning:Now rotate the pins. This helps in the equal distribution of the sol onto the pins. Now pass the cool air. Drying: now the pins are passed via air drying kilns so that the excess water is removed. Stripping: Now the capsules are removed from the pins with the help of the bronze jaws. Trimming: it's a process of cutting in which the excess of length is removed with the help of stationary knives. Joining: now both the halves of the capsules are obtained and they are joined and are removed from the machine. The viscosity of the gelatin sol and the duration of dipping and the rate of spinning determine the thickness.
Empty capsules: The capsule size is determined according to its number. The decreasing order of capsule size is 5<4<3<2<1<0<00 00 is not used generally for human use. Generally the moisture content ranges from 12 to 15% when the capsules are supplied from the manufacturer. And the container should not be opened at high temperatures for long period of time. Even the moisture content should be maintained carefully. If the capsules are stored in low humidity conditions, then the capsules loose water and will become brittle. And at elevated humidity conditions, the capsules will absorb water form the surrounding and will become soft.
Formulation: During the process of randomization and filling there occur several problems. Among them the more prominent problems are: 1. After the process of randomization, the power mixture should flow properly into the during the filling operation. 2. Physical incompatibilities. The capsule consists of the active ingredients and in most of the cases it consists of the diluents too. And during the selection of the diluents: a) Different types of equipments require different types of flow properties and these should be satisfied. The density difference and the size difference between the particles must be as less as possible because this prevents the demixing. b) We must be aware of the incompatibilities that occur during the formulation. The incompatibility reactions that take place at high temperatures and humidity condition should be estimated in advance. c) FDA rules should be taken into consideration while selecting the diluents. Materials generally used as diluents: bentonite, calcium carbonate, silica gel, talc Materials generally used as lubricants: esters of glycol, stearic acid, silicon dioxide, metallic stearates Tests that capsules should undergo after filling: weigh variation, content uniformity, solubility and disintegration.
Finishing operations: After the filling operation is completed, then the polishing is essential and the following procedures are generally applied for that process. 1. Pan polishing: Accelacota coating pan is generally employed for this process. In order to eliminate the dust and to give shining, a cheese cloth liner is used. 2. Cloth dusting: The capsules after the filling operation are rubbed with cloth. This gives shine to the capsules along with elimination of the materials that are tough to remove. 3. Brushing: This is done with the help of brushes and generally vacuum is employed inorder to remove the dust.