Definition: Pharmaceutical preparations that exist in solid form are collectively referred to as solid preparations

Classification

Features:

Preparation process: drug (excipient) ð crushing ð sieving ð mixing (to obtain powder) ð granulation (to obtain granules) ð tableting (to obtain tablets)

concept

The dissolution rate constant k1 of the drug after the tablet contacts the gastrointestinal fluid, the dissolution rate constant k2 of the drug after the tablet disintegrates into coarse particles, and the dissolution rate constant k3 of the drug after the coarse particles are further dispersed into fine particles; k3>k2>k1

Measures to improve dissolution rate

Particle size and particle size distribution

Morphology and specific surface area

density density

Porosity: the ratio of the total volume of the voids between particles and the particles themselves in the powder to the total volume of the powder, which can be expressed as the intra-particle void (V1) rate, the inter-particle void (V2) rate, and the total void (V1 V2) rate

fluidity

packability packability

moisture absorption

Wetting: The phenomenon that the air adsorbed on the surface of the powder is replaced by liquid is called wetting. The nature of this liquid-gas exchange is called wettability. It is often described by the contact angle θ. θ<90° means easy wetting, 90°~180° means no wetting, and 180° means no wetting at all.

Adhesion: The attraction between molecules of different substances that causes particles to adhere to each other.

Cohesion: the property of several particles adhering to each other due to the attraction between molecules of the same substance

Expression form: compressibility, moldability, tabletability

Forms of particle deformation: elastic deformation, plastic deformation, brittle deformation

The mechanism of powder compression molding

Factors affecting powder compression molding

Definition: The process of crushing and grinding large solid materials into small pieces, powder or even ultra-fine powder with the help of mechanical force

Purpose: Adjust the fluidity of drug powder, reduce mechanical irritation, reduce particle size, increase specific surface area, improve bioavailability, etc.

Methods: Dry crushing (commonly used), wet crushing (hard to dissolve in water, use "water flying method"), flow energy crushing, low temperature crushing

Definition: The process of separating drugs of different particle sizes with the help of screens

Types of medicine sieves: punch sieve, woven sieve. There are nine specifications from No. 1 to No. 9. The larger the sieve number, the smaller the inner diameter of the sieve holes.

Definition: The process of thoroughly mixing two or more drugs or components of a prescription

Mechanism: convective mixing, shear mixing, diffusion mixing

Method: Stir and mix, grind and mix, sieve and mix

Instant soft material: Adding a small amount of liquid to solid powder, the liquid evenly wets the inside and surface of the powder particles to prepare a uniform plastic material.

Key: The amount of adhesive added

Requirements: Hold it in your hands and form a ball, then press it lightly and it will fall apart.

Definition: The operation of processing materials into granules of a certain shape and size

Particle forming principle: adhesion and agglomeration

method

Mechanism: When the hot air continuously transfers heat energy to the wet material, the moisture in the wet material continues to vaporize, and the moisture inside the material continuously diffuses to the surface of the material in liquid and gaseous states, so that the moisture in the wet material continues to decrease. And dry

Properties of moisture in materials

Factors affecting drying rate

Drying methods: convection drying, conductive drying, radiation drying (infrared: consumes electricity, microwave: high cost and affects stability), dielectric heating drying, freeze drying (especially suitable for heat-sensitive materials, but requires large investment and high production costs)

Definition: A solid dispersion system made by highly dispersing drugs in an amorphous or microcrystalline molecular state in a suitable carrier material.

Advantages: Improve the oral bioavailability of poorly soluble drugs, can be used to prepare sustained- and controlled-release preparations, improve the chemical stability of drugs, and can be further made into solid dosage forms

Disadvantages: aging phenomenon, small drug loading capacity, difficulty in industrial production

water soluble carrier material

Water-insoluble carrier material

Enteric carrier material

eutectic mixture

Solid solution (extremely fast dissolution rate)

coprecipitate

quick release principle

Principle of sustained release: The carrier material can form a network skeleton structure that can accommodate drug molecules. The drug molecules or microcrystals dispersed in the skeleton must slowly diffuse through the network structure and be dissolved.

Definition: An inclusion body formed by a drug molecule being fully or partially embedded in the hole structure of another substance molecule. It is composed of a host molecule and a guest molecule.

Features: Increase the solubility of poorly soluble drugs, increase drug bioavailability, improve drug stability, adjust drug release rate, mask odor, reduce irritation, and reduce drug loss