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Soft Gelatin Capsules Ingredients: The Ultimate Guide

Maybe you’ve been wondering what makes soft gelatin capsules ingredients.

But again, since the conceptualization of soft gels in the 19the century, they continuously rate highly in terms of consumption level in the pharmaceutical industry.

Of course, many issues contribute to this trend.

But what exactly constitutes soft gelatin capsules ingredients?

I will take you through a comprehensive discussion about all the ingredients of the soft gels. Plus we shall thoroughly analyze each element.

Therefore, as you’ll notice, this guide will be vital to you whether you’re new to this product or even if you’re a specialist.

Let’s begin right away.

Soft gelatin capsules

Soft gelatin capsules

Sections of Soft Gelatin Capsules

First, let’s begin with some basics about Softgel capsules.

Remember, the soft gel is asingleunit pharmaceutical dosage form that comprises a medicinal value in either a liquid or a semi-solid form.

Specifically, the soft gelatin capsules ingredients are mainly active ingredient of the drug in the form of a solution, emulsion, or suspension.

Soft gel capsules

Soft gel capsules

The converse of the soft gels is the hard gelatin capsule which gets manufactured in two halves.

Now, as we earlier stated, the soft gels are favorite in the pharmaceutical industry due to a couple of reasons:

  1. Completely masking the unpleasant odor and taste of the medicines
  2. Easy to swallow
  • Offer the possibility of achieving content uniformity of fewer dosage drugs among others

Now for you to understand the soft gelatin capsules ingredients wholly, it’s much easier to begin first with the specific composition of each segment of the capsule.

That way, you shall deeply conceptualize all that it takes to manufacture the whole dosage form.

Consequently, we shall take a look at the elements of each section.

With that information, let’s switch back to our main question.

The soft gel has got two distinct sections:

  1. Outer shell
  2. Fill matrix

Does this mean all the types of soft gel do have the above-related parts?

It’s absolutely right, no matter the type, size, or form of the soft gel, they all have the above two sections.

For clarification, the soft gels may assume a couple of shapes such as oval, cylindrical, round, or tube-like.

Tub soft gel capsules

Tub soft gel capsules

Oval soft gel capsules

Oval soft gel capsules

However, the sizes of the capsules vary accordingly in the range of 2.5 cm to 1cm even though the proportions maydiffer depending on the type of application.

To make our discussion resourceful, we shall comprehensively discuss each of the two sections in depth.

Let’s begin with the outer shell.

Outer Shell of Soft Gelatin Capsules Ingredients

Even before we look at what makes up the outer shell, I prefer we initially make some brief notes about the outer shell.

This way, it will be easier to understand the shells’ individual elements.

Now, the outer shell of the soft gel is obviously the outer covering of the capsule.

Since we’re dealing with the soft gel; you’ll notice that it’s very soft and smooth. Several components attribute to this form of texture as we shall soon discover.

For some capsules, the outer shell maybe dark or transparent.

Why?

Don’t worry, again, the answer shall come later in the guide.

So as you realize, many factors contribute to the complete formation of the outer shell.

Anatomy of soft gel capsule

Anatomy of soft gelatin capsules

The following are the composition of the outer shell:

  • Gelatin
  • Plasticizer
  • Solvent
  • Opacifiers
  • Preservatives
  • Flavorings
  • Other additives

With that, we will discuss each now.

· Gelatin

Gelatin isone of the significant components of the shell of the capsule. Moreover, it’s very critical in determining some of the shell characteristics.

Consequently, the type of gelatin for use must be approved and authorized by the official pharmacopeias, for example, the United States Pharmacopoeia (USP), European Pharmacopoeia (PhEur).

Additionally, the local authorities may do the same approval.

Importantly, the approvals also take into considerations the physiochemical specifications of each gelatin type.

Again, this procedure is critical whether the gelatin is for manufacturing pharmaceutical, health, or nutrition soft capsules.

Above all, the grades and quality of the gelatin are essential in determining the simplicity of the general manufacturing procedure of the capsule. Also, the condition of the gelatin directly affects the quality of the final shell product.

Generally, we can classify the gelatins in two significant categories,ie. Type A which is a result of acidic hydrolysis of animal skins.

Type B produced by base hydrolysis of bovine bones.

These two classes additionally contribute to the formation of the following forms of gelatin; limed bone (LB), Limed Hide (LH), a blend of LB/LH, Acid bone (AB), Pigskin (PS), a mixture of PS/LB/LH.

For that matter, the pharmacists are always cautious with the parameters of the gelatin.

Some of the useful parameters include gel strength, viscosity, melting point, setting point, particle size, molecular weight, etc.

So what do pharmacists recommend as suitable gelatin for the soft capsule?

They should at least possess the following minimum specifications:

  • The gel strength of 150 – 200 bloom.
  • The viscosity of 2.8 – 4.5 mPas
  • Optimum viscosity breakdown
  • Uniform particle size for quick dissolution.
  • A broad molecular weight distribution.

All the above aspects differ according to the gelatin type you pick.

So which is the best type of gelatin?

Currently, there is no definite answer to that question, but it ultimately depends on your ability to make a proper choice.

Nevertheless, you still need to understand that your choice would also depend on consumer preference levels, your level of technology, and costs.

· Plasticizer

Plasticizers are also other crucial components of the shell.

Always take care when selecting an appropriate one because for soft capsules, you only need to use a non-volatile plasticizer together with the right amount of water to enhance the stability of the capsule.

So generally the function of the plasticizer is to maintain the elasticity and flexibility of the shell during the drying process and even after.

A few of the recommended plasticizers by pharmacopeias and regulatory bodies are polyalcohols such as glycerol, aqueous sorbitol, and their respective combinations.

You also need to take into consideration the type and concentrations of the plasticizer you use. These factors are consistent with the constituents of the fill matrix of the soft gel.

Moreover, the optimum weight ratio between the dry plasticizer to that of the dry gelatin should vary in the range of 0.3 and 1.0.

You should, therefore, strive to maintain the ratio at that range since it determines the strength of the outer shell.

In conclusion, a suitable plasticizer should be the one that appropriately interacts with the gelatin molecules. Such kind of interactions contributes to the reduction of theglass transition temperature of that of the gelatin shell.

Softgel capsules

Softgel capsules

· Solvent

Water is the universal solvent in use here.

By far, water forms a very crucial component of the soft gel shell. As a show of its importance, water occupies about 30 – 40 % of the overall wet gel formulation.

Water compliments the proper processing procedure, especially during the gel formulation and encapsulation.

Besides, the ratio of water by weight to that of the dry gelatin should vary in the range of 0.7 to 1.0 though these values vary by the viscosity of the type of gelatin you use.

· Opacifiers

The opacifiers have got only a single but essential function in the shell.

You only need to add these chemicals if you want to initiate the formation of a dark/ opaque shell. Note that, the use of such substances isn’t always at will but when dealing with a suspension type of formulation.

Elsewhere, it’s preferred to prevent photodegradation of light-sensitive active ingredients.

The most common opacifier is titanium dioxide.

Titanium oxide on its own produces a whitish opaque shell. Opaque colored shell is possible with the use of a mixture of several pigments.

· Colorings

The kinds of colors you see on the shells are only possible with the use of the colorants. The colorants are essential for the correct identification of products.

Importantly, as a general rule, always ensure that the color of the shell is darker as compared to that of the fill.

And even before coming up with a color, you need to verify that the corresponding mixtures of the color doesn’t result in darkening or fading away of the shell during storage.

Indeed fading of the colors often happens due to the reaction between the colorants and the corresponding shell/filling ingredients.

Furthermore, you can choose either a synthetic or natural colorant.

· Flavorings

The shells are tasteless and inconsistent with the taste of the drugs.

Ethyl vanillin, essential oils, and sucrose are the primary flavoring agents that help mask the tastes of the drugs.

· Preservatives

Preservatives are an additional component that strives to keep the product viable and safe for predetermined long term storage.

Now those are all the ingredients of the shell.

It’s time we move onto the components of the fill. Shall we?

Fill Material for Soft Gelatin Capsules Ingredients

Structure of soft gelatin capsules

Structure of soft gelatin capsules

Now the primary purpose for developing the soft gel was undoubtedly to dispense the active medicinal values.

Inside the shells, these active compounds formulations are either in a liquid solution, semi-solid solution, suspension or emulsion.

The formulation of the fill is unique and takes into account some factors. Have a look at the following minimum conditions that your formulation need to fulfill.

  • To guarantee the chemical stability of the active ingredients.
  • To enhance the bioavailability of the active component.
  • To provide an efficient filling process
  • To lead to the achievement of a physically sturdy capsule.

With that, let’s shift to the fill materials.

But before that, we have to classify the fill matrix.

We can generally categorize the fill materials into three groups, ie. Oily mixtures, solutions fills, and suspension fills

i. Oily mixtures

The oily mixtures are also occasionally referred to as neat substances since they purely consist of oily liquids.

ii. Solution fills

The solution fills consists of active components of the drugs dissolved in a carrier solution. Perfect examples are soybean oil and miglyol 812, polyethylene Glycols specifically PEG 400 – 600.

Apart from that, this kind of fill matrix may include any other non-volatile solvent with zero effect on the gelatin shell such as dimethyl isosorbide, diethylene glycol monoethyl ether, surfactants, etc.

The components don’t end there; you can as well incorporate some of the following optional ingredients in the solution fill:

  • Water and any other solvent such as alcohol with a concentration of 10% w/w essential for added solubility.
  • Glycerin in the range of 1 to 4 % w/w.
  • Polyvinylpyrrolidone to a maximum of 10% w/w mixed with PEG. The whole combination increases the solubility of the drug. Besides,it improves the stability of the soft gel.

iii. Suspension fills

The suspension fill comprises of the active ingredient uniformly dispersed in a carrier formulation.

An added advantage of the suspension is because it comfortably accommodates upto 30 % solids without destabilizing the viscosity. In cases of viscosity problems during filling, to lower it, then you may heat the suspensions upto a temperature of 35°C.

For the suspended solids, they need not exceed 80 mesh mill.

Ordinary suspension fills ingredients include:

  • Oily mixtures: such as the soybean oil mixed with beeswax (4 – 10% w/w) and lecithin (2 -4% w/w). The lecithin in use is essential for improving the flow of the material in the process, providing some degree of lubrication.

gelified oil.

  • Polyethylene glycol: semi- solids fill should be PEG 800 – 1000, however for solid fills PEG 10,000 – 100000. Or a blend of the both.
  • Glycerides with long chain fatty acids

While other notable optional ingredients include:

  • Surfactant: includes sorbitan products, i.e.,polysorbate 80/ lecithin.

Now up to this level, I am sure you already understand what it takes to come up with an established outer shell and fill the matrix.

Now the pharmaceutical industry manufacturing process always takes into considerations the post preparation treatments to almost all products, including the soft gels.

It’sa standard and necessary procedure in an equal magnitude.

Continue reading for that discussion.

Post Preparation Additives and Shell Coatings as Soft Gelatin Capsules Ingredients

It’s a non-compulsory practice to conduct some post-treatment and coating on the soft gelatin capsules just after production.

Though it’s an extra conventional measure, believe me, failure to conduct such practices may minimize the quality of your products.

CBD soft gelatin capsules

CBD Soft gelatin capsules

The following are the benefits that come with post treatments and shell coatings:

  • Product stability
  • Modification of the dissolution rate
  • Production of enteric capsules

Aside from the benefits, what does it take to perform a suitable post-treatment?

Post-treatment is quite a technical procedure that you need to do with the utmost care.

First of all, you need to get that;it’s an indisputable fact that the protective coatings increase the stability of the soft gelatin capsules.

Meanwhile, without these coatings, the stability problems arise as a result of the hygroscopic nature of the shell together with its high heat sensitivity.

So how do you do the coatings?

Using an emulsion based formulation to coat is a prime way to go. Apart from that, you may use a solution of water and alcohol.

Above all, the fluidized-bed air-suspension technique is yet another technological approach that is applicable for coating the soft gels.

Another post-treatment technique is by the use of aldehyde. The aldehyde post-treatment aims at significantly reducing the dissolution rate of capsules in the stomach.

Other post-treatments include initially sub coating the soft gelatin capsule with an alcoholic solution. Thereafter, coating the same product with a gastro-resistant, enteric-soluble polymer.

By the way, do you want to start the process of making soft gelatin capsules, here are some useful links for you:

Conclusion

At last, you are at the end of this guide.

Important points you need to remember is that having an in-depth understanding of the ingredients is a closer step towards handling the manufacturing process of the soft gelatin capsules.

Also, make sure you always contact your local regulatory bodies or authentic pharmacopeiasalways to keep yourself updated with the required and approved ingredients for use.

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