What is dosage form

Medicines are usually not taken in their natural form. They are converted to some other forms known as dosage form by mixing with some other ingredients, in order to make it easy for dispensing and administering.

So what is dosage form..?

Dosage forms are the means by which drug molecules are delivered to the site of action within the body. Here active drug molecules are combined with excipients to deliver drugs to the site of action inside the body to generate maximum effect with minimum adverse effects.

We can take a cup of coffee as an example to understand what is dosage form.

When we feel tired or sleepy we will take a cup of coffee to get some energy. Here the active ingredient which gives us energy is caffeine. Since we are not taking caffeine directly, we extract caffeine into water to form coffee and add sugar to mask the unwanted taste of caffeine. Also we add milk to make it more tasty and sometimes add flavoring agents like menthol leaves. Here caffeine is an active molecule and coffee is dosage form.

What is the use of dosage form

To mask unwanted taste or odor:

Medicines having unwanted taste and odor are difficult to take. In this case medicines are formulated to capsules, coated tablets or made into syrup.

To provide accurate dosing:

Formulating medicines to tablets, capsules, syrups etc make it easy to take accurate dose. It is especially important when the active drugs are more potent. In this case drug dose may be in milligram count.

Protection from gastric juice:

Some medicines are easily destroyed in stomach gastric juice. For example Insulin, in this case it is converted to injection form. Also some tablets are provided with a special enteric coating to bypass destruction from gastric secretions.

To increase solubility:

Some insoluble medicines are made soluble by converting them to emulsions and suspensions

Delivering medicines through an alternate route:

In certain conditions medicines cannot be given through a specific route, then we have to prepare a formulation for administering through another route. For example, in the case of a vomiting patient we cannot give medicine by oral route. Then we have to deliver drugs in the form of suppository or patches.

To increase duration action of medicines:

Drugs having shorter duration of action can be formulated to a controlled release formulation. Which release drugs slowly and in controlled manner and provide a prolonged duration action from single dosage.

Examples include extended release tablets, implants, slow release patches etc.

For insertion to certain body cavities:

Examples are suppositories, pessaries, dental cones etc

Applying to specific area of body:

Examples are ointments, pastes, creams, liniments etc

To provide optimal and fast action

Examples include aerosols to deliver drugs to respiratory tract, sublingual tablets, Injections etc

Increase stability of medicines:

Medicines which are easily destroyed by atmospheric effects can be made into special coated preparations or packed into ampoules.

Different types of dosage forms

We can classify dosage forms in different ways,

According to their physical properties:
- Solid dosage form
- liquid dosage form
- semisolid dosage form etc
According to their route of administrations:
- Oral preparations
- Topical preparations
- Rectal preparations
- Parenteral preparations
- Inhalations
- Ophthalmic preparations etc.

According to site of application
- Skin: Ointments, Cream, Lotion
- Eye: Drops, Ointments
- Ear: Drops
- Teeth: Tooth powder, Paste
- Foot: Creams, Ointments, Powders
- Nasal: Solutions, Sprays, Inhalations
According to uses
- Internal use: Tablets, Capsules, Syrups etc
- External use: Ointments, Creams, Lotion, Spray, Liniments etc

We can discuss some important dosage forms here

Solid dosage forms

Tablets:

A tablet is the hard compressed unit solid dosage form. Tablets are the most common dosage form. Tablets are prepared by mixing active ingredients with specific excipients and compressed using a tablet machine. There are different types of tablets

Coated tablets
Pills
Chewable tablets
Effervescent tablets
Buccal tablets etc

Capsules:

Capsules are unit solid dosage forms in which medicines in solid or liquid form are encapsulated in gelatin capsules. There are two types of capsules

Hard gelatin capsules
Soft gelatin capsules

Lozenges:

Lozenges are unit solid dosage forms intended to be dissolved slowly in the mouth. They are usually used for soothing sore throats or relieving coughs.

Suppositories:

They are unit solid dosage form carrying medications intended to be inserted to any body cavities other than mouth. They release medicines by melting or by dissolving in body fluids.

Liquid dosage forms

Solutions:

Here one or more active ingredients are dissolved in a suitable vehicle. There are two types of solutions, solutions for internal use and for external use.

Syrups:

Syrup is a concentrated solution of sucrose in water. Syrups help in masking the bad taste of medicine and also it increases stability.

Suspensions:

Suspensions are biphasic liquid preparations in which fine solid ingredients are dispersed in a suitable liquid.

Emulsions:

These are also biphasic liquid preparations where two immiscible liquids are made miscible by dispersing one in another in the form of small droplets and stabilizing them using an emulsifying agent. It is of two types,

Oil in water emulsions: here fine oil globules are dispersed in an aqueous media.
Water in oil emulsions: here fine water droplets are dispersed in an oily media

Elixirs:

These are pleasantly flavored and sweetened preparations of potent drugs. These preparations usually contain a high proportion of ethanol or sugar.

Liniments:

These are liquid preparations meant for external application. This is usually applied with friction.

Semisolid dosage forms

Ointments:

Ointments are semisolid greasy preparations meant for application to the skin or mucous membrane. They may be medicated or non medicated.

Creams:

Creams are also semisolid dosage forms but they are less greasier than ointments. They are of two types.

Oil in water type: here fine oil droplets are dispersed in a water soluble continuous phase.
Water in oil type: here fine droplets of aqueous phase are dispersed in a continuous oily phase.

Pastes:

Pastes are semisolid preparations containing a high proportion of finely divided solid substances. They are usually used for their topical action.

Gels:

They are transparent semisolid preparations for external use.

There are also other types of dosage forms that includes,

injections:

Which supply drugs directly to blood circulation.

Trans-dermal patches:

These are patches applied to specific areas of skin which release medicaments to the bloodstream through skin. They can be used for controlled drug delivery of medicines.

Aerosols:

Here one or more medicines are packed in a pressurized dispenser, which delivers medicines to affected areas in the form of a fine mist.

Intrauterine devices ( IUDs ):

Intrauterine devices are one of the major contraceptive methods. These dosage forms are made to be placed in the uterus.

Conclusion

In this article we discussed What is dosage form. Dosage forms are means by which medicines are delivered to their site of action inside the body. There are several types of dosage forms. Medicines are formulated to dosage forms in order to ease their dispensing, storing, patient acceptability and improving their effectiveness.

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What is the use of dosage form