Appropriate Conditions for Empty Capsule Storage
Gelatin empty capsules contain more water than HPMC empty capsules and lose water faster. The water content of gelatin capsules is between 13% and 16%; The water content of HPMC capsules is between 3% and 8%.
It should be noted that the environmental conditions have a very large impact on the empty capsule, because its moisture content will gradually reach equilibrium with the surrounding relative humidity. If every step of the production process (including warehousing, storage, transportation, filling and packaging) is not controlled, empty capsules can easily dry out or become too wet.
The conditions required to maintain the capsule moisture content within the desired range are:

Capsules’ Storage and Transportation
1. Storage conditions of gelatin capsules: temperature is 10-25℃; humidity is 35-65%;
2. Storage conditions of HPM capsules: temperature is 10-30℃; humidity is 45-75%;
3. Under the condition of high temperature and humidity, the water content of the capsule will change, and the capsule will be sticky and deformed;
4. Empty capsules do not need to be exposed to an environment with large changes in relative humidity. As the part of moisture and moisture control, capsules should always be stored on trays off the ground, away from hot water or air radiators, hot water pipelines, steam pipelines and any other sources of condensation (such as under water pipes or in freezers);
5. Capsule packaging containers should be kept away from direct sunlight, heat and other hot things, even in sealed containers. Prevent capsule from heat damage, pouch, deformation and caking;
6. Do not store the capsules in an overheated or overly dry environment. To maintain the correct temperature, avoid storing capsules in direct sunlight, elevated locations (as heat rises), and near hot spots near ceiling lights and HVAC vents.

Proper Conditions During Capsule Filling
Via the following appropriate conditions and measures, it is possible to ensure that capsules maintain their physical and chemical stability throughout the packaging process, thus guaranteeing the quality of the final product and the safety of the patient.
Ambient Humidity Control:
Using a portable industrial humidifier can indeed help maintain the relative humidity of the filling chamber in cold weather to prevent the capsules from losing moisture due to drying and avoid embrittlement or deformation.
Monitor and record ambient humidity to ensure it is within specified limits.
Capsule Protection:
It is a good practice to use a resealable bag to seal an opened capsule carton, which reduces the time the capsule is exposed when not in use and prevents moisture absorption or contamination.
Ensure operators wear gloves when handling capsules to reduce direct contact and the risk of contamination.
Vacuum Control of Capsule Filling Machine:
Adjust the vacuum level of the filling machine to ensure that the empty capsules can be effectively separated without causing damage to the capsules. (Too much vacuum can cause pinhole ruptures in the capsule dome, which can cause product to leak out of the capsule.)
Check and maintain the vacuum system regularly to avoid problems caused by equipment failure.
Avoid deformation caused by excessive capsule accumulation.
Temperature Control During Packaging:
When using heat source equipment such as blister packaging equipment and thermal tunnel, strict control of temperature and time is required to avoid damage to the capsule due to overheating.
Capsules should not be exposed to high temperatures for long periods of time, as this may affect the stability and tightness of the capsule.

Packaging Material Selection:
Choose materials suitable for the capsule packaging, which should be able to protect the capsule from external factors such as humidity, light and oxygen.
Make sure the packaging material does not react chemically with the capsule.
Storage Conditions after Packaging:
The packaged capsules should be stored in a suitable environment, avoiding extreme temperature and humidity conditions.
Capsules should be stored in accordance with the specified storage conditions to ensure their quality during their validity period.
Quality Control:
Sampling inspection is carried out during the packaging process to ensure the integrity, tightness and appearance quality of the packaging.
Document key parameters during the packaging process such as temperature, humidity and time for quality review and improvement.
For gelatin capsules that are more susceptible to water vapor, pay close attention to humidity control in the packaging area, as a small amount of surrounding air will be sealed along with the product.
Also, carefully consider whether to include a desiccant (for absorbing moisture) in the package. The desiccant may cause the capsule to over-dry.

Problems that Arise When Conditions Control is Not in Place
The quality of empty capsules does suffer when climate control is not in place, and here are some of the things that can go wrong and their consequences:
Capsule Size Changes:
High humidity can cause the gelatin capsules to expand hygroscopically and change size, which can cause problems with the capsules during filling and sealing.
Size changes may also affect the dissolution rate of the capsule and the release of its contents.

Crosslinking:
When stored for a long time under high temperature and humidity conditions, the gelatin capsule may have cross-linking between molecules, resulting in the capsule being difficult to dissolve and affecting the efficacy.
Brittleness:
Capsules with too little moisture will become brittle and easily break during handling, affecting the integrity and filling efficiency of  capsules.
When the moisture content of gelatin capsules is less than 13%, brittleness increases, which may lead to increased losses during production.
Sticky Capsules:
Under high temperature conditions, capsules may become loose and sticky, making it easy for capsules to stick to each other and difficult to separate, affecting the filling and packaging process.
Change of Melting Point:
High humidity may affect the melting point of the gelatin capsule, so that the capsule does not dissolve in the body as quickly as expected, affecting drug release.

Static Accumulation:
Low relative humidity will increase the generation of static electricity, which will cause the capsules to adhere together and affect the normal operation of the filling machine.
Static electricity can also attract dust and other particles, increasing the risk of pollution.

To Prevent These Problems, Here Are Some Prevention and Mitigation Measures:

• Environmental monitoring: Regularly monitor and record the temperature and humidity of the production area and storage environment.
• Dehumidifying and humidifying systems: Install dehumidifying or humidifying systems as required to maintain suitable environmental conditions.
• Static control: Use static eliminator or anti-static material to reduce static accumulation.
• Material selection: Select capsule materials suitable for environmental conditions, such as HPMC capsules are more stable under dry conditions.
• Packaging optimization: The use of appropriate packaging materials and design to protect the capsules from environmental factors.
• Storage management: Ensure that the storage conditions meet the specific requirements of the drug and avoid high temperature, high humidity or extreme dry conditions.
• Quality control: Strict quality control is carried out in the production process to ensure that the capsule quality meets the standard.