Factors Influencing the Dissolution of Solid Dosage Forms

In theory, in vivo drug testing is the most important and reliable basis for evaluating drugs. However, in the development of oral solid  dosage forms, the method of measuring bioavailability is used to screen and evaluate each new prescription and process, which is time-consuming and costly. money. Although the results of in vivo and in vitro tests may not be completely consistent, they have certain relevance. Because the in vitro dissolution test is simple and feasible, it can be regarded as a cost-effective quality test and control method. The determination of in vitro dissolution rate can provide an important basis for the formulation of preparations and process screening, and avoid blindness in the research and development of solid forms.

Solid  dosage forms are generally more stable than aqueous solutions, but chemical reactions occur when drugs are in the solid state. The reaction mechanism is generally more complex than that in the solution state, and there are more factors that affect the reaction rate. The compatibility between drugs and drugs, the compatibility of drugs and excipients, and the interaction between the components may lead to the degradation of  Solid  dosage forms. Medicilon has rich experience in the research and application of innovative drugs and generic drugs. It provides one-stop and systematic formulation R&D services covering innovative drugs and generic drugs to meet the needs of customers at different stages of development and is committed to solid dosage forms. , Semi-solid preparations, liquid preparations and innovative preparations, etc. to provide contract research and development services. At the same time, Medicilon has rich R&D experience in sustained and controlled release formulations, microparticle formulations, and protein and peptide pharmaceutical formulations, and many mature products have been handed over to customers.

Through the determination of dissolution, the pros and cons of new dosage forms can be compared, the influence of excipients, carriers and diluents on drug dissolution and its principles can be investigated, and the varieties, dosages and best prescriptions of excipients can be screened scientifically. Therefore, investigating the influence of different technologies and processes on drug dissolution is of great significance to the design of new processes.

The main factors affecting the absorption of the active ingredients in solid dosage forms in the body include the disintegration time of the preparation, the size of the drug particles, the solubility of the drug itself and the structure of the drug powder, etc., and these factors are closely related to the dosage form, the prescription and the preparation process. Correlation, that is to say, the dosage form, formulation prescription and process are directly related to the dissolution of the drug.

The influence of dosage form on dissolution rate　

One of the most common forms of drug administration is oral administration. The most common are tablets, pills, capsules, granules and solutions. The dosage form is closely related to the dissolution of the drug. The dissolution rates of Niuhuang Jiedu Pills and Niuhuang Jiedu Pills were measured with baicalin, berberine, chlorogenic acid and total anthraquinone as indicators. The results showed that the dissolution rate of honey pills was 2 to 3 times slower than that of sugar-coated tablets. Obviously, changing the Niuhuang Jiedu Pills to Niuhuang Jiedu Tablets is conducive to the release of the drug. The release volume of Maodongqing dry extract capsules in 2 minutes is equivalent to the release volume of sugar-coated tablets in 30 minutes, and the release volume of capsules at 50 minutes is more than 5 times that of sugar-coated tablets. Su Bing Dripping Pill T50 is twice as fast as Guanxin Suhe Pill, and its clinical efficacy is obvious and all biological parameters are better than Guanxin Suhe Pill.

The in vitro dissolution test can be used to select the ideal dosage form. In the treatment of acute diseases, a dosage form with high dissolution rate should be used, and the drug will be effective quickly; in the treatment of chronic diseases, a dosage form with a small dissolution rate should be used to make the drug work slowly; when the treatment of cancer, a targeted release target should be selected. To the preparation to reduce the toxicity to normal cells.

In the final analysis, the influence of dosage form on dissolution lies in the influence of preparation prescription and process. Different dosage forms of the same drug must have different preparation prescriptions and processes. Different dosage forms exist as the external manifestations of different preparation prescriptions or processes.

The influence of formulations on dissolution rate　

The formulation prescription includes two parts: the drug component and the adjuvant. For example, western medicine tablets are solid dosage forms  prepared by compression or injection molding, containing pharmaceutical ingredients and appropriate diluents, disintegrating agents, coating materials, coloring agents and other pharmaceutical excipients. Among them, the properties of the drug (solubility, crystal form, particle size, etc.) have a greater impact on the release and dissolution of the active ingredients in the tablet. Additives (types and dosages of excipients, etc.) play a major role in the disintegration of the formulation. The composition of traditional Chinese medicine preparations is more complicated, and the influence of additives on the dissolution of the medicine is generally considered in the choice of preparation prescription. The choice of additives can affect the release performance of the preparation. The flavonoid extracts of the traditional Chinese medicine Qinglan, Pueraria lobata, and rutin were made into tablets with different excipients. The results indicate that different fillers have a significant effect on the dissolution of different flavonoids. . For example, researchers developed rhubarb controlled-release tablets using hydroxypropyl methylcellulose as a blocker, and the optimized prescription met the in vitro dissolution requirements for sustained-release preparations in the U.S. Pharmacopoeia.

The influence of preparation process on dissolution rate　

When the formula is the same but the preparation process is different, it will also have a significant impact on the dissolution of the drug. Small changes in the production process will cause the dissolution of the preparation to change. Fragrant lotus pills use different production processes, and the dissolution rate is quite different. Xianglian pills from different manufacturers have the highest dissolution rate of 83%, while the lowest is only 30%. Therefore, the preparation process can be improved from the method of mixing the drug and the excipients, and the preparation of the insoluble drug into a solid dispersion, and the dissolution of the drug can be improved.

In the research and development of solid dosage forms, to improve the dissolution rate of solid dosage forms of drugs, it is necessary to adopt appropriate methods to promote the dissolution of drugs on the basis of a full understanding of the physical and chemical properties of the drugs.

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