What Are The Key Influencing Factors of Capsule Filling

The key influencing factors of capsule filling mainly involve the properties of the contents, the quality of the capsule shell, process parameters, and environmental conditions, which directly affect the accuracy of filling, the stability of the capsule, and the quality of the product. The following is a specific analysis:

1、 Content properties 1. Liquidity impact: Powder with poor fluidity (such as strong moisture absorption and high friction between particles) is prone to clogging the equipment during the filling process, resulting in uneven filling volume or filling failure. Example: Traditional Chinese medicine extract powder, due to its high hygroscopicity, may clump in the filling machine hopper if no lubricant (such as magnesium stearate) is added. 2. Impact of bulk density: Fluctuations in bulk density can lead to significant differences in the weight of contents of the same volume, affecting the accuracy of filling dosage. Response: Adapt to different bulk densities by adjusting the metering parameters of the filling machine, such as screw speed and plunger stroke. 3. Particle size distribution impact: Particles that are too fine can easily generate dust, resulting in weight loss or equipment pollution during filling; If the particles are too coarse, they may block the filling channel or cause layering during filling (separation of coarse and fine particles). Example: If aspirin powder does not pass the 80 mesh sieve, uneven particle size may cause fluctuations in the filling amount of hard capsules. 4. Moisture absorption and viscosity effects: Drugs with strong moisture absorption are prone to clumping due to moisture (such as glucose), and materials with high viscosity (such as traditional Chinese medicine containing polysaccharides) will adhere to the inner wall of the filling equipment, affecting the filling efficiency.

2、 Quality of capsule shell 1. Moisture content standard: The moisture content of hard capsule shell usually needs to be controlled between 12% and 15%. Impact: If the moisture content is too low, it is prone to brittle cracking (such as when the capsule shell becomes brittle and fractures when locked); If it is too high, it is easy to adhere (such as when it is higher than 18%, the capsule shell softens and cannot be sorted properly). 2. Key parameters of dimensional accuracy: The inner diameter, length, and wall thickness errors of the capsule shell must comply with pharmacopoeia standards (such as the inner diameter error of hard capsule No. 0 being ≤± 0.1mm). Impact: Inconsistent size can lead to inaccurate positioning of the capsules in the filling machine, resulting in powder leakage or loose locking. 3. Material characteristic types: Gelatin capsule shells need to pay attention to freezing force (strength) and transparency, while plant capsules (such as HPMC) need to pay attention to film-forming and temperature resistance. Example: If the freezing force of the gelatin capsule shell is insufficient (such as below 150 Bloom), it may deform due to pressure during filling.

3、 Process parameter control 1. Effect of filling speed: Excessive speed can lead to uneven distribution of contents in the filling chamber (such as powder stratification), especially for materials with poor fluidity. Optimization: Adjust the filling machine speed according to the characteristics of the content (for example, when filling powder into hard capsules, the speed is usually controlled at 20-40 revolutions per minute). 2. Filling pressure and locking force for hard capsules: Insufficient locking pressure can cause the capsule cap to not close tightly, resulting in powder leakage; Excessive pressure may crush the capsule shell. Soft capsules: In the compression method, the molding pressure needs to be uniform, otherwise it may cause uneven wall thickness and rupture of the capsule. 3. Temperature and humidity environment requirements: The hard capsule filling workshop usually needs to control the temperature between 18-26 ℃ and humidity between 45% and 65%. Influence: When the humidity is high, hygroscopic contents are prone to deliquescence (such as penicillin drugs); Excessive temperature can cause softening of the contents of soft capsules (such as oily drugs). 4、 Equipment performance and maintenance 1. Accuracy type of measuring device: screw type measuring is suitable for uniform powder, plunger type is suitable for particles, and multi station measuring disc is suitable for high-precision requirements. Impact: Wear of measuring devices (such as screw thread wear) can cause deviation in filling amount, and regular calibration is required (such as weekly calibration with standard weights). 2. Capsule sorting and positioning accuracy issues: If there are foreign objects or wear on the capsule sorting track of the filling machine, it will cause the capsules to tilt or get stuck, making it impossible to fill accurately. Example: The directional device of the hard capsule filling machine malfunctions, which may cause the capsule cap to face upwards and prevent the contents from being filled into the capsule body. 5、 Accessory and Formula Design 1. Accessory Selection Function: Adding diluents (such as lactose) can improve the bulk density of the content, lubricants (such as talc) can enhance fluidity, and anti sticking agents (such as silica) can reduce clumping. Example: When filling traditional Chinese medicine extract powder, adding 1% to 3% micro silica gel can prevent moisture absorption and clumping. 2. Compatibility impact of formula: The reaction between the contents and the capsule shell material (such as cross-linking between aldehyde containing drugs and gelatin capsule shell) may cause the capsule shell to become brittle or the drug to degrade. 6、 Environment and Operating Standards 1. Cleanliness Requirements Standard: Pharmaceutical capsule filling must be carried out in a D-class clean area (dust particles ≤ 3520000/m ³) to avoid microbial contamination. Impact: Particles in the air may clog the filling equipment or cause excessive microbial content in the capsule. 2. Key skills of operators: Adjustment of filling machine parameters (such as measuring disk depth) and troubleshooting of equipment (such as checking locking pressure when powder leakage occurs) should be performed by skilled personnel to avoid human errors.