Capsules have become one of the most popular dosage forms due to their lack of medicinal taste, unlike tablets, quick relief from symptoms, ease of administration, and various other reasons. Considering this increased demand, the empty pharmaceutical capsule market will be valued at four billion U.S. dollars by 2032.
While this is a generalization comprising all empty capsule types, it is important to differentiate them. Therefore, this article digs into the various types of medicine capsules, their manufacturing process, and health benefits. Let’s dive in!
What Is a Capsule?
A capsule is a shell or cylindrical dosage form used in healthcare to enclose medicines and supplements for scientific purposes and to administer treatments orally or as a suppository—delivering easily dissolvable capsules through the anus or vagina. There are different types of pill capsules, and they are mostly characterized by vegetarian and non-vegetarian capsules.
These dosage forms comprise gelatin (hard or soft) and non-gelatin shells generally derived from hydrolysis of collagen (alkaline, enzymatic, thermal hydrolysis, or amino acids like proline, glycine, and hydroxyproline) of animal origin, producing nonvegetarian capsules or cellulose-based, making vegetarian capsules.
Types of Capsules in Pharmacy
On the subject of the classification of capsules, you’ll come across dosage forms for vegetarians and non-vegetarians. However, the differentiation goes beyond these two. So, if you’ve been wondering what capsules are found in what type of cells, keep reading to gain insight into the types of capsules in pharmacy and their differences.
1. Gelatin Capsules
Gelatin capsules are categorized into hard and soft shells. These shells are made using different manufacturing processes and usually have different shell designs; they all provide an effective and protective cover from light and atmospheric conditions for medicines or supplements. Here’s a detailed overview of each type of gelatin capsule.
a. Hard Gelatin Capsules
Hard gelatin capsules usually have a cylindrical shape and contain solid, powdered medicines, granules, or other active ingredients. The capsule shell usually has a head (cap) and bottom (body) design, and their locking rings prevent you from tasting the cell’s content.
Manufacturers design them and supply the empty hard gelatin shells to drug companies, who in turn, use dosator type capsule filling machines and polishers to fill them with the appropriate ingredients and improve their physical appearance. It is important to know that hard gelatin and other gelatin capsules are non-vegetarian.
This is because gelatin is derived from animal bones, skins, and cartilage, unlike plant products used in manufacturing starch and other vegetarian capsule cells. So, if you’re a vegetarian or prefer plant-based capsule shells, gelatin capsules may not be for you.
Now, there are various examples and types of hard gelatin capsules. For starters, they can be filled with:
- Dry solid active ingredients, such as powders, granules, and tiny pellets.
- Semi-solids, such as pastes and suspensions
- Sometimes liquids are called liquid-filled hard capsules (LFHC)
While infusing hard gelatin capsule shells with liquid active ingredients is a relatively new practice, it is perfect for liquid substances with less amount of free moisture. Besides the dosage forms that these hard empty shells can be filled with, here are common examples of medications administered in this form.
- Various types of amoxicillin-capsules
- Acebrophylline Capsules
- Carbonyl Iron, Vitamin C, Folic Acid, Vitamin B12, and zinc Capsules.
- Doxycycline & Lactic Acid Bacillus Capsules
- Itraconazole Capsules
- All types of omeprazole capsules
- Lactobacillus, Bifidobacterium & Saccharomyces Capsules.
- Lycopene, multivitamins, and multimineral Capsules, etc.
These capsule packaging types are often used for many reasons, including customer convenience, dual-action (since some may contain two different substances), and their ability to break down fast and act quickly.
b. Soft Gelatin Capsules
Unlike hard gelatin capsules, soft-gel capsules are wider and have a semi-transparent appearance. They are animal-based capsules that absorb quickly and offer faster relief from symptoms than hard-gel capsules. However, soft gelatin capsules are usually more resistant to pressures like crushing, piercing, and cutting.
Usually, soft-del capsules require specialized manufacturing processes and equipment, like the soft-gel encapsulation machine, because the dosage contains more moisture than hard gelatin-filled capsules, so they require direct sealing instead of the two-way method used for hard-gel capsules. For these cells, plasticizers like glycerine and sorbitol are used to maintain the shells’ stability and elasticity.
While manufacturers currently fill hard gelatin shells with liquid, the soft gelatin cells are the best type of capsule to use for oils and other liquid dosages because they are designed to accommodate higher amounts of free moisture. Now, the common types of soft gelatin capsules include the following:
- Lipophilic oils and liquids
- Triglyceride oils, such as soya bean oil
- Hydrophilic liquids
- Polar liquids with a sufficiently high molecular weight.
- Polyethylene glycol (PEG).
- Self-emulsifying oils.
Currently, many drug manufacturing companies use vitamins, medicines, and supplements made from the above-listed liquid ingredients to fill capsules. Some common examples of soft gelatin capsule dosage forms include:
- Fish gelatin capsules
- Diclofenac potassium liquid-filled soft gelatin
- Cyclosporine soft gelatin capsules
- Vitamin E capsules
- Various types of cod liver oil capsules
- Anti-malaria medications, etc.
All these soft gelatin capsules are manufactured in cylindrical, tube, ovoid, pear, or spherical shapes. Additionally, they usually contain oils, highly moisture-free solutions, suspension, and pastes. While it may seem like soft gelatin gel shells can contain all solutes, the reverse is the case, as certain highly soluble substances can not be filled into them to avoid damaging the cells.
Moving on, hard and soft gelatin dosage forms are not the only non-vegetarian capsule shells used in medicine, vitamin, and supplement filling. Other animal-based cells, like modified release and enteric capsules, are equally effective and can be taken orally or as a suppository. For a better understanding, these capsule types are discussed below.
2. Modified Release Capsules
Modified release pharmaceutical capsules or dosage forms are used in capsules to dissolve a medicine, vitamin, or supplements over time in order for the ingredients to be released slowly and steadily into the bloodstream. This process can be carried out for both hard and soft gelatin capsules, and it is administered less frequently than immediate-release dosages.
What is the purpose of modified-release tablets? The purpose or need for this type of administration is to control the rate at which the ingredients in the dosage are released into the bloodstream. Besides that, they are also used to maintain a specific concentration of the substance in your blood to help healthcare practitioners achieve various objectives.
3. Enteric Capsules
Once a medication is administered orally, it can be easily broken down by stomach acids before it passes through the intestine and is distributed to the areas experiencing symptoms via the bloodstream. To prevent this absorption from happening in the stomach, enteric coating, which is used during oral delivery of medicines, vitamins, and supplements, degrades quickly in the stomach, preventing the ingredients from being released until they get to the intestine.
4. Vegetarian Capsules
Unlike gel capsule types, which are made from animal bones, skin, and cartilage, vegetarian capsules or veggie caps are made up of cellulose—a complex polysaccharide that forms the principal component of the plant cell wall. Since these shells are made from vegetables, they are ideal for people who do not eat fish, meat, and other animal products.
Like non-vegetarian capsule shells, veggie caps comprise hard and soft capsule shells. In addition, there are different types of vegetarian capsules, and they are characterized by the following:
a. Pullulan Capsules
Pullulan capsule shells usually comprise purified water and pullulan—a natural, water-soluble mucopolysaccharide, a mature food additive consisting of three glucose units linked by α-1,4 glycosidic bonds. Pullulan is made through the fermentation of tapioca because of its resistance to oxygen.
Over the years, it has become one of the most common substances used in the production of 100% veggie caps due to its coating ability and excellent physicochemical properties. Aside from its coating properties, pullulan is tough and has a low moisture content. Therefore, it is used to fill water-sensitive vitamins, medicines, and supplements.
b. Hydroxypropyl Methyl Cellulose (HPMC) Capsules
In most cases, the main ingredient of a vegetarian capsule is hydroxypropyl methylcellulose. These capsule shells usually contain HPMC and purified water, and the cellulose is obtained from the hydrolysis of plants through the etherification of starch. These capsules are completely safe and ideal for vegetarian dosage forms.
Like pullulan capsule cells, the hydroxypropyl methylcellulose shells have a low moisture content of about three to eight percent, making them suitable for filling moisture-sensitive drugs, vitamins, and supplements. Since hydroxypropyl methylcellulose capsules are made from plants, they are vegetarian or herbal products.
c. Starch Capsules
This vegetarian type capsule is a solid oral delivery dosage form made of potato starch and a common but effective alternative to hard gelatin pharmaceutical capsules. Starch capsules have a relatively high moisture content compared to other vegetarian capsules and are suitable for enteric coating.
Different Types of Capsule Shells
Capsule shells are made from different materials, including cellulose and animal products. These materials determine the physical properties and ensure that they fit the active ingredients that will be filled with, mostly liquids, dry solids, granules, small pellets, paste, and suspensions. Here are the common types of capsule shells:
- Hard Gelatin Capsules
- HPMC Capsules
- Fish Gelatin Capsules
- Starch Capsule
- Pullulan Capsules
- Polyvinyl Acetate (PVA) Capsules
- Liquid-filled Hard Capsules (LFHC)
- Soft Gelatin Capsules (SGC)
Aside from their base products, vegetable and non-vegetarian capsule shells come in various sizes, which are the same for all types of gelatin and HMPC capsule shells but slightly different for vegetarian capsule shells, and they are numbered:
- Size 000: The 000 soft and hard shells hold about 1000 mg of active ingredients, whether it is collagen type 1 and 3 capsules content or any other medications, but are hardly available for vegetarian dosages.
- Size 00: This capsule holds about 735 mg and is available for gelatin and veggie caps.
- Size 0: Holds about 500 mg, also used for veggie caps and gelatin capsules.
- Size 1: Holds 200 mg of vitamins, medicines, and supplements for all capsule types.
- Size 2: It is only available for gelatin and HMPC shells. This capsule holds 165 mg for light density ingredients, 260 mg for medium density, and 370 mg for heavy-density density.
- Size 3: With a light density of vitamins, medicine, and supplement filling, this capsule holds 135 mg. But for a medium density, it holds 210 mg and 300 mg for a heavy density. Additionally, it is only used in gelatin and HMPC fillings
- Size 4: The size 4 capsule shell holds about 95 mg of all filling types but only for gelatin and HMPC cells.
- Size 5: Empty capsules size 5 are made for gelatin and HMPC fillings, and they hold between 80-160mg, depending on density.
When producing or filling vitamins, supplements, or medicines, it is important to determine the type of content to be filled. It’ll help you choose your capsule size accurately. You can make more informed decisions with the above chart describing what type of capsule can be filled in certain cell sizes.
Types of Capsules by Uses
We’ve established that capsule shells usually contain dry, powdered ingredients or miniature pellets and oils, pastes, and suspensions. Also, hard and soft capsules can be coated to resist disintegration in the stomach before passing through the intestine to the areas experiencing symptoms. Some of the commonly available capsules and their uses include:
1. Vitamin E Capsules and Their Uses
Vitamin E capsules are antioxidants that prevent and treat low levels of vitamin E. These vitamins maintain the health of your brain, blood cells, eyes, and skin as;
- For the prevention of skin cancer
- Fast wound healing
- Protection from UV rays
- Reduction of skin itchiness
- Brightening the skin
- Anti-aging and treatment of wrinkles
- Reduction of scar appearances
- And prevention of eczema.
Vitamin E capsules and oils have many advantages for the skin and other body systems. For instance, it increases fertility in both men and women. It can be taken orally as a supplement or applied directly to treat skin irritation from UV rays and inflammations.
2. Mucopolysaccharides Collagen Type 1 and Vitamin C Capsules
Mucopolysaccharides Collagen Type 1 and Vitamin C Capsules are nutritional veggie supplements for treating tendonitis and osteoarthritis. These capsules help strengthen the tendons connecting the bones to the muscles, promote bone growth, and enhance wound repair. Aside from the bones, it supports the health and function of other connective tissues, such as cartilage, skin, ligaments, and blood vessels, while fighting infections.
3. Undenatured Type 2 Collagen Capsules
Like mucopolysaccharides collagen type 1 and vitamin C capsules, the undenatured type II collagen caps are also used to strengthen bones, enhance wound repair and healing, provide lubrication to the joints, and improve bone growth. But unlike collagen type I, the undenatured collagen type II are non-vegetarian capsules, so if you are a vegetarian or are allergic to chicken or eggs, do not use these capsules.
4. Cod Liver Oil Capsules Type B
Cod liver oil capsules support brain and eye health, prevent blood from clotting easily and lower blood pressure, especially among elderly people. These capsules have many advantages, some of which are yet to be proven scientifically. However, they are administered to patients suffering from depression, arthritis, vitamin B6, vitamin A, iodine, vitamin D, iron deficiency, and many other conditions.
5. Collagen Type 1 Capsules
Collagen type I is found in the skin, tendons, ligaments, and bone, and supplements containing this protein are used for wound healing and when mixed with vitamin C, they provide great nourishment for the skin. These capsules mostly support healthy skin, hair, and nails. Additionally, they are recommended for patients suffering from osteoarthritis, scleroderma, and many other conditions.
6. Collagen Type 2 Joint Complex 120 Capsules
With aging, the body starts to produce cartilage tissue more slowly and where a person has been injured badly without an active blood flow, the cartilage will not heal as fast as it would if there was active blood flow. So, the collagen type 2 joint complex 120 capsules promotes joint health and increases your inner strength.
7. Collagen Type II 500 mg Capsules
The collagen type II 500 mg capsules support skin, bone, joint, and cartilage health. However, they are non-vegetarian capsules, meaning that they are made from animal-based ingredients. Hence, they are not ideal for consumption by vegetarians and those allergic to chicken and other dairy products.
8. Liver Capsule Collagen Type
As of January 2023, about 4.5 million adults were diagnosed with liver diseases, and the majority of these infections resulted from heavy alcohol use and viral hepatitis. While others can be linked to obesity, type 2 diabetes, injecting drugs using shared needles, and exposure to other people’s blood and body fluids. Collagen supplements protect your liver from toxins and can help repair liver damage.
Comparison Between Different Capsule Types
While many capsule types may have similar shapes and other characteristics, they all have certain features that differentiate them from the others. Here’s a tabular representation of how each capsule type differs from the other.
|Parameter||Hard Gelatin Capsule||Soft Gelatin Capsule||Vegetarian Capsules|
|Appearance||Opaque||Wider and semi-transparent||Can be opaque or semi-transparent|
|Shell Types||Head and body||Hermetically sealed||Can leverage the head and body shell type of the hermetically sealed cells.|
|Filling Content||Powders, granules, tiny pellets, pastes, and suspensions.||Lipophilic oils, soya bean oil, hydrophilic liquids, polar liquids, and polyethylene glycol, and self-emulsifying oils.||Contain dry solids, semi-solids, and liquids, but all are usually of plant origin.|
|Sizes||000, 00, 0, 1, 2, 3, 4, and 5.||000, 00, 0, 1, 2, 3, 4, and 5.||00, 0, and 1. However, sizes 000, 00, 0, 1, 2, 3, 4, and 5 are all available for HMPC capsules.|
This article highlighted the various types of capsules with examples, their sizes and shell types, and common vegetarian and non-vegetarian capsules available, and their uses. This is because knowing the capsule type you want to fill or manufacture determines the size and kind of filling and polishing machine you’ll need.
But if you need help choosing what equipment will best suit your production size and needs, SaintyCo can help you decide. They manufacture high-performance soft gel encapsulation machines, gummy-making equipment, capsule polishers, doctor-type capsule filling machines, and other quality pharmaceutical machines. Contact SaintyCo to learn more about how they are helping drug manufacturers.