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What are 4 Types of Capsules | Preparation of Gelatin Powder

Various types of capsules are used for many purposes. The capsules has many uses as well as specific characteristics, and it is important to follow the instructions for taking them properly. In this article, I will provide information about the types of capsules and the manufacturing of gelatin capsule shells.

 


What are 4 types of capsules

Types of Capsules

There are the following types of capsules:

1) Hard Gelatin Capsules

2) Soft Gelatin Capsules

3) Modified Release Capsules

4) Enteric Capsules

 

classification of Types of Capsule



Hard Gelatin Capsules

The hard gelatin capsules are constituted of two pieces called cap and body. It looks like a cylindrical form that is closed at one end. The smaller piece is called a cap whereas the larger one is called a body that contains the drug substances and is covered by the cap.

Hard gelatin capsules consist of solid APIs (Active Pharmaceutical Ingredients). Drugs of different properties should be added in the form of tablets or pellets in hard gelatin capsules.

The manufacturing of Hard gelatin capsules through the dipping of capsule shell shaped into the gelatin solution. Then the film of gelatin gets dried on the pins and removed from the pins. Finally, unlock the body and cap pieces.

 

Size of Capsule for Human Use

The size of hard gelatin capsules ranges from largest (000) to smallest (5).


Size of Capsule for Human Use

 

Soft Gelatin Capsules (Softgel)

Soft gelatin capsules are prepared from gelatin and these capsules are thicker than hard gelatin capsules. It is plasticized by adding either glycerin or sorbitol. The ratio of plasticizer depends upon the content nature that is to be filled into the soft gelatin capsules as well as the environmental conditions.

Soft gelatin capsules are generally filled while they are formulated and sealed with the help of machines.

Soft gelatin capsules generally consist of solid or liquid drugs that are dissolved in liquid to form a paste. Sometimes powders, as well as granules, may also be filled in soft gelatin capsules

These capsules are one-piece gelatin shell that contains suspension, semisolids, or liquid.

The formation of soft gelatin capsules is the same as the hard gelatin capsules, except for the plasticizers and different moisture lot parts. To maintain the stability and elasticity of soft gelatin capsules, plasticizers (Glycerol, Sorbitol) were added. It also contains preservatives to prevent or stop fungal growth.


Modified Release Capsules

Modified-release Capsules are either hard or soft capsules. To modify the rate of releasing the active ingredients of the capsules, in these capsules, the contents or shell or both are prepared by a special technique.

If a water-soluble drug is in a hard capsule and a faster release rate is required, then the excipients should be hydrophilic and neutral and for slow-release water-soluble drugs, the excipients will slow the release rate.

By incorporating a small quantity of citric acid and sodium bicarbonate to assist in opening the capsule through the evolution of carbon dioxide, rapid release from capsules can be obtained.

To increase the penetration of water and faster dissolution, a small concentration of sodium lauryl sulfate may be added to the gel of a soft gelatin capsule, and for slow release alginates or polymers can be added.

 

Enteric Capsules

The Enteric capsules are either hard or soft gelatin capsules that withstand the gastric fluid and release their contents by dissolving in intestinal fluid.
The microbial quality of enteric capsules should be maintained as per their acceptance criteria because while manufacturing, packaging, storage, and distribution of capsules, the possibilities of microbial growth in gelatin are on the higher side.

Enteric Coated Capsules are mainly made to dissolve the alkaline liquid in the intestinal tract.

 

HPMC (Hydroxypropyl methylcellulose) Capsules

These capsules are mainly constituted of Hydroxypropyl methylcellulose and purified water. HPMC is obtained by the hydrolysis of plants and made by etherification. HPMC is a type of cellulose.

The HPMC capsules can be stable at a low static charge, and at low humidity levels with low moisture content that is 3 to 8%. Generally, these capsules are suitable for highly reactive molecules.

As HPMC is derived from plants, it is also a type of herbal product. A kind of vegetarian capsule.

 

Starch Capsules

These types of capsules are prepared from potato starch.
 
These capsules are suitable for enteric coating as their dissolution is pH-dependent.
 
Moisture content - 12 to 14% w/w.

Pullulan Capsules

Pullulan (polysaccharide that is derived from a fungus called Aureobasidium pullulans) capsules are dietary supplements as it is a natural and vegetarian capsules. Basically, it is an alternative to gelatin.
 
Pullulan capsules are moisture-resistant and stable at various pH levels.

 

Polyvinyl Acetate (PVA) Capsules

Synthetic polymer (PVA) capsules are prepared by dissolving polyvinyl acetate in a solvent such as polyethylene glycol (PEG) 400 or acetone and then applying the solution coat directly from the capsules.

Polyvinyl acetate (PVA) capsules are dissolved in water or other liquids as well.

Liquid-Filled Hard Capsules

Liquid-filled hard capsules are prepared either from HPMC or from gelatin and can be used for filling liquid or semisolid substances such as paste, or suspension.

The tablets, pellets, and others capsules as a combination can also be filled in liquid-filled hard capsules.

Liquid-filled hard capsules are mainly used for moisture-sensitive drugs.

As the amount of active ingredient in each capsule is controlled hence, liquid-filled hard capsules also provide a more precise and consistent dose.

Liquid-filled hard capsules are also cost-effective as compared to soft gelatin capsules.

Liquid-filled hard capsules also improve stability as well as enhance bioavailability.

 

How Gelatin is Produced Industrially?

 

How Gelatin Is Produced Industrially?


What is The Process of Capsule Manufacturing?

Primarily, capsules are prepared by using gelatin, although the replacements as per the suitability are also over there for example - Starch and Hydroxypropylmethylcellulose.

Gelatin (a mixture of proteins) is extracted from animal collagen that is derived from animal skins and bones through the hydrolysis of partial alkaline or acids.

Through this technique gelatins obtained are of two types named type A and type B gelatin.

 

Type A gelatin

Type A gelatin is obtained by acid treatment of pig skin through Hcl, H₂SO, H₂SO4, or H₂PО at a pH range of approximately 1 to 3 for one day.

Type B gelatin

Type B gelatin was obtained by using an alkaline treatment of demineralized bones that were dipped or immersed into calcium hydroxide slurry for 1 to 3 months.

After that gelatin is extracted by washing it with hot water many times. Then the gelatin solutions got cooled to form a gel.

Now, water got evaporated which results in the production of dried gelatin.

 

Isoelectric points

Type A - 7 and 9

Type B - 4.7 and 5.3

Which results in differences in solubilities in terms of pH.

 

The molecular weight range for gelatin is - 15000 to 250000.

Bloom strength describes the grade of gelatin.

Bloom strength is the weight required to lower a plunger to the desired depth within an aged gelatin gel that is 6.66% w/w in water.

Gelatin is used as a primary material in capsule manufacturing because of the excellent biological properties as well as excellent physicochemical properties of gelatin material including:

Gelatin is widely used as a component of foods. It is a non-toxic material.

Gelatin has been manufactured from bovine collagen (which comes from cows).

At room temperature, gelatin is soluble in biological fluids. (The capsules of gelatin do not dissolve, only swell when immersed into less than 30°C of aqueous solution).

Due to the excellent rheological properties of gelatin, the production of capsules is done by dip processing.

Gelatin has excellent mechanical properties and capsule-forming properties as well.

At low temperatures, gelatin undergoes a sol-gel transition, and hence, gelatin is easily converted to the rigid (gel) state by allowing warmed solutions of this material to cool.

I tried to make you engaged by giving the basic information about the Types of Capsules and the Preparation of Gelatin. If you have not understood anything then you can ask your doubt in the comments. If you want to learn more about solid oral dosage forms below are useful sources.

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