How to accurately control the release time of capsule medicine:There are various dosage forms of drugs commonly used in life, such as tablets, capsules, granules, oral liquids… Even the same drug has different dosage forms, such as aspirin, tablets, injections, ointments, suppositories, syrups, children’s tablets, effervescent tablets, sustained-release tablets, enteric coated tablets, microcapsules and many other dosage forms. They are all drugs. Why should we distinguish so many forms?
First of all, we need to understand a basic drug knowledge. What is a drug dosage form? Drug dosage form refers to the dosage form of drugs, which is prepared by adding appropriate excipients into drugs and through some preparation processes in order to meet the drug demand and adapt to the physical and chemical properties of drugs before they are supplied for clinical use. These forms are called drug dosage forms. There are dozens of drug forms, and there are twenty or thirty commonly used. Different dosage forms are equivalent to putting on different “coats” for drugs, and their curative effects and taking methods are also different.
Common dosage forms
Powder is an ancient traditional dosage form, which is rarely used in western medicine. In pharmaceutics, powder is defined as a dry powder preparation made by crushing drugs and appropriate excipients, and then mixing them evenly. Because the powder has small particle size and large surface area, it is easy to disperse and takes effect quickly. Granules, commonly known as “granules”, are dry granular preparations with a certain particle size made by mixing raw materials and appropriate excipients. It can be understood that on the basis of powders, some viscous excipients are added to become particles with larger radius.
Tablet is a round or special-shaped (such as oval, diamond, cartoon, etc.) sheet-like solid preparation made of raw drugs and suitable excipients. More than half of the commonly used oral drugs are tablets, and many of the calcium tablets, vitamins and family drugs are tablets. The utility model has the advantages of accurate dose, stable physical and chemical properties, long storage period and small volume.
Capsule refers to a kind of solid preparation filled in hollow capsule or sealed in soft capsule shell after drugs or auxiliary materials are added. It can be mainly divided into hard capsule, soft capsule, sustained-release capsule, controlled-release capsule, enteric coated capsule, etc. The main materials of the capsule shell are gelatin, plant cellulose and their derivatives, which will slowly dissolve after entering the human body. Wrapping drugs with capsules can not only cover up the bad smell of drugs, avoid the influence of water, air and light, improve the stability of drugs, but also ensure the release of drugs at an appropriate time for the purpose of diagnosis and treatment.
Is capsule a product of modern civilization?
As early as 1500 AD, the first capsule was born in Egypt. At that time, there was no machine to press tablets. The Egyptians put the drug dispersion that was not easy to collect and take into the capsule that could be dissolved in the stomach. But this capsule is only a closed pill with a certain space inside. It was not until 1846 that the common two section hard capsule was invented.
In 1840, tablet press appeared and tablets were born. Of course, tablets are simpler and more direct than “drug end + drug skin”, but capsules continue to be retained because of their irreplaceable role.
First of all, many drugs are effective and bitter. Everyone knows the truth of “good medicine tastes bitter”, but if it’s really their turn to eat, people are still willing to choose something with good efficacy and less difficult to swallow. Secondly, some of the efficacy time is very short, and the efficacy has evaporated before reaching the affected part.
Adding a layer of capsule as a buffer can prevent the effect from happening too fast. Some drugs taken directly will be directly decomposed by specific enzymes in the body and will not work, so take them in capsules. Some drugs must be absorbed through the intestine to work, and it takes a certain time for the drugs to reach the intestine. The capsule can ensure that the drugs will work at a certain time. Therefore, for drugs that irritate the esophagus and gastric mucosa, or drugs that taste bad, are easy to volatilize, are easy to be decomposed by saliva in the mouth, and are easy to inhale into the trachea, people still choose to put them in capsules.
Who has the final say what time the capsule will melt?
Many people only value the components of drugs. In fact, more often, the action time and position of efficacy are more important. Now there are two kinds of capsules, one is dissolved in the stomach and the other is dissolved in the intestine.
Gelatin, cellulose and polysaccharides can be made into capsules. These things used for coating quickly come to the stomach after passing through the mouth, throat and esophagus that don’t like them. The stomach dissolving capsule dissolves directly here and begins to work. Some drugs that stimulate the gastric mucosa, are easy to be damaged in gastric acid or can be better absorbed in the alkaline environment of the intestine are often made into enteric coated capsules, which need to reach the intestine to release them. Although the capsule solves the problem of premature dissolution of drugs in the mouth, how to solve the problem of too fast dissolution in the stomach?
Enteric coated capsules often use a copolymer including methacrylic acid copolymer and methacrylic acid copolymer, commonly known as acrylic resin. It doesn’t matter if you don’t know the meaning of methacrylic acid copolymer and methacrylate copolymer. It’s just understood as a medicinal resin. This resin is like a timing “alarm clock” installed on a capsule. It can control the time and location of the release of active ingredients. Its principle is that this capsule will dissolve only when exposed to alkaline environment, so no matter how much acid in the stomach, it can’t help others. Drugs can hold high the exemption card all the way and play a role directly in the intestine.
However, successfully reaching the target organ is only the first step. To make the drugs in the capsule work for a long time, we still need to rely on the small pills in the capsule. These small pills have the same core containing drugs. They look no different, but in fact they are not exactly the same. The difference lies in the “clothes” they wear outside their core. This layer of clothing is usually composed of organic matter with large molecules, which is evenly wrapped outside the core of the small pill. After the capsule dissolves, this layer of “clothes” will also slowly dissolve in the digestive tract until it completely disappears, exposing the core part. The pill will not release the drug until the core is exposed.
If the “clothes” are made thicker, it will take more time to dissolve, and the time of drug release will be delayed. If the thickness of the “clothes” is properly controlled, we can release the drugs in the small pills when needed. Making the coating layer very thick can delay the time of drug release, but can not increase the time of drug action. Even if the drug can take effect after 12 hours, it can not last for 12 hours. In order to solve this problem, people usually divide the small pills in the sustained-release capsule into several groups and let them wear clothes of different thickness.
Suppose these small pills are divided into three groups. The first group is the rapid release of small pills. Without coating, the drugs in this group of small pills can be released immediately. The second group is medium speed release small pills, wrapped with a relatively thin coating layer, and the drug release speed is slower. The third group was slow release small pills, with the thickest coating and the slowest drug release.
Put these three groups of small pills into capsules. When the capsule is eaten, the capsule shell first dissolves in the digestive tract, and then the small pill is released quickly to release the drug. The released drug is absorbed into the body by the gastrointestinal tract, and the drug concentration in the body increases gradually. Soon, the concentration of the drug in the body will be enough to produce the effect.
At the same time, the drugs entering the body will also be metabolized and gradually discharged from the body, so the concentration of drugs increases and then begins to decrease gradually. At this time, the coating layer of the medium speed release small pill just dissolved almost, and joined the ranks of drug release. When the drug concentration provided by the medium speed release pill began to decline, the slow release pill took its place.
Through the cooperation of the three groups, the drug concentration can be maintained at a stable level for a long time. In this way, it is not a problem for the sustained-release capsule to remain effective for a long time. In addition to sustained-release capsules, there are many technologies that can control the release rate and time of drugs. The application of these technologies not only makes the use of drugs more convenient, but also makes the treatment effect more stable.
Why are they colorful?
Some capsules are transparent, but some have colors. The colors at both ends of the capsule are often different. Some people think that each drug has its own color, or the color represents its safety. In fact, they think too much. The different colors of capsules are mainly determined in the production process.
First of all, for the sake of beauty, the bright capsule color can reduce people’s rejection of drugs. After all, the powder in the capsule always makes people feel very bitter. Secondly, the pharmaceutical factory produces more than one drug, and different colors are easy to distinguish. As for those transparent capsules, it is convenient for people to notice the state of drug powder or particles inside and reduce the risk.