What are hard capsules?
Hard capsules are formed by soaking the metal mold (mold pin) in the coating liquid.
Hard capsules were invented in the mid-19th century by the Frenchman Lehuby, and later they were refined into the shape we have today by the American Hubel. In most cases of this high-safety product form, powders, granules and tablets are enclosed in a capsule and the cap is sealed. Hard capsules are valued for their high added value in terms of the convenience of being edible on their own, easy to handle, and for their appearance. In addition to health foods, hard capsules are used in a wide range of fields, including medicinal products, non-medicinal products, general processed foods, animal medicines, cosmetics, and sundries. Additionally, in recent years, the use of hard capsules has expanded even further with the development of technology for inserting oil-based liquids as well as solid materials.
Hard capsule form
|Capsule size||No. 00||No. 0||No. 1||No. 2||No. 3||No. 4||No. 5|
|Empty capsule weight (g)||0.12||0.10||0.08||0.06||0.05||0.04||0.03|
|Powder filling volume (estimate g)||0.40～1.75||0.33～0.80||0.23～0.65||0.20～0.55||0.12～0.40||0.10～0.25||0.07～0.12|
|Major axis of outline (cm)||2.50||2.20||1.90||1.80||1.60||1.50||1.10|
|Minor axis of outline (cm)||0.86||0.77||0.70||0.64||0.60||0.50||0.47|
Strengths of hard capsules
1. High blending ratio of active ingredients
Since the manufacturing process has few additives such as water, alcohol, starch, lubricant or disintegrant, a high blending ratio of main ingredients can be configured.
2. Excellent stability of contents
The capsule membrane has excellent oxygen barrier properties and stability.
In particular, our functional pharmaceutical production known as the “B-Capsule” has excellent content stability and masking effects.
3. Few physical quality deterioration factors of human processing factors in manufacturing process
The manufacturing process does not have temperature-/heat-processing, humification/drying processes, or pressurizing, etc., so there are very few physical factor that could cause quality deterioration.
Hard capsule manufacturing method
General preservation/storage conditions for health-foods
Except for special items, health-foods (soft capsules, hard capsules, seamless capsules, tablets, granules, jellies and mini-drinks) are normally kept at room temperature, and even from the perspective of the composition of contents and changes in appearance, etc., it is necessary to avoid high temperatures and high humidity, as well as sudden changes in temperature, and as with general foodstuffs, efforts should be made to keep health-foods in stable and secure conditions. In general, the following conditions are desirable.
◎Temperature 30℃ max. (avoid placing inside vehicle, on vehicle dashboard/trunk, or in bag, etc.)
◎Humidity RH60% max. (Avoid kitchens/drainage area and places where rust/mold easily occur)
◎Light . (Avoid direct sunlight)
◎Oxygen (air) . (After opening, firmly close stopper or fastener, etc. to prevent contact with air)
Detailed preservation/storage conditions are described below.
(1) Changes in the appearance of hard capsules
In general, hard capsule products should preferably be stored at a normal temperature (15-25°c) with a relative humidity of 40-60%. In conditions other than these, or if there is a strong external impact, exterior changes in appearance may occur, such as capsule adhesion and capsule deformation, as shown in the following examples.
① Capsules are easily broken if stored in a refrigerator or freezer for a long time (one month or more).
② Due to the special characteristics of gelatin in terms of being weak against heat and humidity, gelatin-made hard capsules will soften and there will be noticeable adhesion and deformation, etc. if the capsules are left exposed to high temperature/high humidity conditions.
③ Moisture on the capsules will cause the membrane to dissolve, resulting in adhesion and deformation.
④ External impacts may cause hard capsules to break due to the thinness of the membrane. In particular, pullulan hard capsules tend to be weaker against impacts than gelatin-made hard capsules.
⑤ Even though the membrane strength of HPMC hard capsules is relatively strong, the membrane itself is thin, so it tends to be weak against external impacts. As the membrane is soft, indentations may occur as external pressure increases.
⑥ Although the contents of the hard capsule may appear to decrease due to increased vibrations and tapping that cause the powder to clog (compress), the fill amount (volume) has not changed.
(2) Stability of hard capsule contents
The stability of the ingredients contained within hard capsules depends on the ingredients. Hard capsules comprise a body and a cap. The cap section is not hermetically sealed, so the stability is somewhat lower than soft capsules.
(3) Summary of hard capsule storage and preservation conditions
As mentioned above, hard capsule products should preferably be stored at normal temperatures (15-25 °c) with a relative humidity of 40-60%. As far as possible, please avoid high temperature/high humidity and low temperature/low humidity conditions.
Also, indentations occur easily as the membrane on hard capsules is thinner than that of soft capsules, so please take sufficient precautions against external impacts.
Hard capsules mostly contain fine powders, but they can also be filled with liquids (oils). Sunsho Pharmaceutical presents the liquid-filled “B-Capsule”, which has a sealed cap section. In comparison to hard capsules, B-Capsules are incredibly airtight, and are suitable for making products from strong-smelling materials. Please feel free to contact us about this.
Hard capsule Q&A
1. What is a hard capsule?
2. Why use hard capsules?
3. Does the storage/handling of hard capsules require special attention?
4. The color of the capsule seems to be slightly different from the previous product…
5. There appears to be a gap in the capsule contents…
6. There seems to be less content than in the hard capsules we purchased last time…
7. We are bothered by the smell of the content…
Q1. What is a hard capsule?
A. Hard capsules were invented in the mid-19th century by the Englishman Murdock, and later they were refined into the shape we have today by the American Hubel. In most cases of this high-safety product form, powders, granules and tablets are enclosed in a capsule and the cap is sealed.
Hard capsules comprise a cap and a body, and are sometimes referred to as a two-piece hard capsule. In most hard capsules, a locking mechanism with an uneven surface, such as gaps on both the cap and body, is used to tighten the bond between the cap and body. They are valued for their high added value in terms of the convenience of being edible on their own, easy to handle, for their appearance, and the ease of imprinting. In addition to medicinal products, hard capsules are used in a wide range of fields, including medicinal products, non-medicinal products, animal medicines, agricultural chemicals, health foods, general processed foods, and sundries. Additionally, in recent years, the use of hard capsules has expanded even further with the development of technology for inserting oil-based liquids as well as solid materials.
Q2. Why use hard capsules?
A. Hard capsules are an incredibly convenient product form that is filled with powder or granules and can be consumed on its own. Also, additives can be reduced to a minimum, so the main ingredient composition ratio can be increased.
As heating, pressurization, and dehydration are not required in the production process, the contents do not deteriorate during production. Also, because there are only a few production processes, short deadlines can be met.
As with hard capsules and soft capsules, the food ingredients can be delivered to the customer in as fresh a condition as possible, so it is perfectly suited to health-foods.
Q3. Does the storage/handling of hard capsules require special attention?
A. Hard capsules should be stored away from direct sunlight and protected from high temperatures/high humidity. Consume quickly once opened. Children and elderly people should take hard capsules slowly with plenty of water or in the bath in order to avoid choking.
Due to the characteristics of the gelatin used in hard capsules, the membrane may become soft or sticky if stored in high temperature/high humidity locations. Please store hard capsules at room temperature (21°c -25°c) and with a relative humidity of 35-50%. Also, if cooled or dried excessively, hard capsules break easily, so please avoid long-term (one month or more) storage in a refrigerator (5-10°c) or freezer (-0°c or below).
Hard capsules should be handled with care as the membrane is thin and may break apart due to strong external impacts. Pullulan capsules, in particular, tend to be weaker against impacts than hard capsules that use gelatin. When using pullulan capsules, please take precautions during transportation such as using buffer materials and avoid stacking the product.
Q4. The color of the capsule seems to be slightly different from the previous product…
A. Transparent capsules and hard capsules have a thin membrane, so the color of the contents may be visible. Capsules mainly contain natural raw materials derived from plants and animals, and the color is not regulated using coloring. Accordingly, the color may change over time, and the appearance of the product may differ slightly to the previous product. We appreciate your understanding in this matter, as minor differences in the color of the capsules do not affect the ingredients or the quality.
Q5. There appears to be a gap in the capsule contents…
A. After filling the body of the hard capsule with the required quantity of contents using a filling machine, the cap is locked. There may be a gap on the top part of the cap. Also, vibrations may cause the contents to move to one side, and a gap may appear, but please be assured that the quantity of the contents is controlled so that it is at a fixed amount.
Q6. There seems to be less content than in the hard capsules we purchased last time…
A. The bulk density of the powder contents of the hard capsule may vary in each stage of production depending on the processing time and different conditions, etc. Changes in the bulk density of the contents may cause the contents to appear to have decreased, but please be assured that the quantity of the contents is controlled so that it is at a fixed amount.
Q7. We are bothered by the smell of the content…
A. Hard capsules are formed of a cap and a body, so there may be microscopic openings in the joining section and the smell of the contents may escape. However, please be assured that the contents are a food and can be eaten safely. If the smell is too troublesome, the smell of the contents can be masked using the “B-Capsule” product, developed in-house at Sunsho Pharmaceutical, which covers the body and cap with a band seal.
The above details are general information based on various publications, literary information, and internal research publications and experience. Depending on the product, there may be some differences, so please contact the sales department at Sunsho Pharmaceutical for specific cases.