Dosage Forms: Classification and Definitions


Most of the drugs cannot be administered directly in pure chemical form, they need to be change in appropriate dosage forms to administer to the patients. After converting them into a specific dose formulation, they are given to the patients in various dosage form through various routes of administration. Medicines reach the site of action through various types of dosage forms. These dosage forms ranges from simple powder from to complex formulations. Each dosage form has its own set of advantages and disadvantages. Understanding of various dosage forms helps healthcare professionals to take appropriate decision regarding patient treatment. In this article we will see the various dosage forms.

Dosage form

Dosage form is a physical form in which a medication is administered to a patient. It is a combination of Active Pharmaceutical Ingredients (API) and excipients in the formulation. It is a mechanism by which Active Pharmaceutical Ingredients are administered to site of action of the body to generate maximum desired effect and to minimise the side effects.

Active Pharmaceutical Ingredient (API)

The Active Pharmaceutical Ingredient (API) also known as the active substance or drug substance. It is the biologically active component in pharmaceutical drug product. It is the chemical substance responsible for the therapeutic effect of the medication. The API undergoes rigorous testing and regulatory approval processes to ensure its safety, efficacy and quality before incorporated into finished pharmaceutical product.


Excipients are inactive ingredients in pharmaceutical formulation which helps in various purposes other than providing therapeutic effects. They are essential components of drug products and contribute to stability, bioavailability, appearance and palatability of the dosage forms. Excipients include substances like fillers, binders, disintegrants, lubricants, preservatives, flavourings, colourants and coatings.

Need of various dosage forms

Diverse patient needs

Patients have different preferences, abilities and medical conditions that may require specific dosage form. For example, paediatric patients may require liquid dosage form due to difficulties in swallowing dosage form, while adult patients can easily take solid dosage form.

Optimized drug delivery

Every drug has various chemical properties and pharmacokinetic profiles, which require a conversion of drug into specific dosage form for optimal absorption, distribution, metabolism and excretion. For example, some drugs require sustain release formulation to maintain therapeutic levels in body.

Enhanced patient compliance

Dosage form which are convenient, palatable and easy to administer improve patient compatibility to prescribed regimens.

Improved bioavailability

Certain drugs exhibit poor solubility or low bioavailability which can be addressed through specialised dosage forms such as liposomes, nanoparticles or solid dispersions. These formulations enhance drug dissolution, absorption, which helps to maximize the therapeutic efficacy.

Localised therapy

Topical dosage forms such as creams, ointments and patches help for targeted delivery of drug to specific sites which minimises the side effects to other parts of the body and maximise local therapeutic action.

Stability and shelf life

Different dosage forms offer varying degrees of stability and shelf life. Formulations that are susceptible to degradation or instability may require specialised formulation to maintain potency and efficacy.

Emergency situations

In emergencies or critical care setting rapid drug onset is essential. Dosage forms like injectables, intranasal sprays or sublingual tablets offer quick absorption and onset of action.

Classification of dosage forms

classification of dosage forms
classification of dosage forms

Solid dosage forms

Powders: These dosage forms comprise micron sized, finely fragmented particles. Medicated powder intended for oral use usually dissolve in liquid, so that patient can drink it for its therapeutic action. It usually comes in small sachets. For example, ORS sachets.

Tablets: Tablets are solid dosage form. A tablet may contain one or more Active Pharmaceutical Ingredient, which are compressed together with excipients (like preservatives, binders, flavouring agents, etc). Tablets come in various shapes, colours. Different types of tablets are,

Effervescent tablet: This tablet dissolves in water due to release of gas. The gas is produced due to the reaction of bicarbonates with citric or tartaric acid. This reaction helps the tablet to dissolve in water.

Chewable tablet: This dosage form meant to be chewed. This type of tablet is given to patients who have difficulty in swallowing.

Sublingual tablet: This type of tablet is designed to be placed below the tongue. In this drug is directly absorbed into the bloodstream through mucosal membrane.

Enteric coated tablet: This type of tablet has special coating which protects tablet to be dissolve in stomach, so it can dissolve in intestine. This type of tablet used to prevent degradation of medicine by gastric juices in stomach, so it can be absorbed in intestine.

Advantages of tablet dosage form: Tablets are convenient to administer, easy to manufacture and offer accurate dosing.

Disadvantages of tablet dosage form: For patients with swallowing difficulties, tablets may pose challenges. Some drugs cannot be formulated into tablets due to their chemical properties or stability issues.

Capsules: Capsules consist of a gelatinous shell enclosing one or more drugs in either powder, granule or pellet form.

Advantages of capsule dosage forms: Capsules offer versatility, allowing for the combination of different drugs or formulations.

Disadvantages of capsule dosage forms: Capsules are more expensive to manufacture as compared to tablets.

Lozenges: This is a solid dosage form made up of sugar and gum base. This need to be sucked inside the mouth until it dissolved. They are typically used to treat the cough and sore throat.

Suppositories: Suppository is a type of dosage form introduced into body cavities other than mouth, such as rectum, vagina, nose or ear. They can easily melt at body temperature. It is used for the patients who has difficulty in swallowing.

Granules: It is a dosage form composed of small, discrete particles known as granules. These granules typically consist of the Active Pharmaceutical Ingredients along with various excipients, such as binders, fillers and disintegrants. These excipients help in the formation and stability of granules.

Pills: API and excipients are contained in the small pill. Pills are generally smaller in size compared tablets.

Semisolid dosage forms

Ointments: It is an oil-based preparation and contains medication. It is applied externally on the skin. Ointments are resistant to being removed with water, sweat or any other body secretions.

Creams: It is an external semi solid dosage form which may or may not contain any medication. It consisting of a water-in-oil or oil-in-water emulsion.

Paste: It is a semi solid dosage form consisting of a homogeneous mixture of a frug substance and a suitable base or vehicle. It has a smooth, thick consistency and used for topical application.

Gels: It is a semi solid dosage form consisting of a network of a solid particles dispersed in a liquid medium. They have a jelly like consistency.

Liquid dosage forms

Droughts: It is a liquid oral formulation comprising of single or several doses of medication.

Elixirs: It is a liquid dosage form containing one or more API dissolved in a hydroalcoholic solvent. Elixirs are usually sweetened and flavoured to improve taste and palatability.

Emulsions: It is a liquid dosage form consisting of two immiscible liquids, typically oil and water, stabilised by an emulsifying agent.

Suspensions: It is a liquid dosage form consisting of a finely divided solid particles suspended in a liquid medium. These particles are not dissolved but dispersed throughout the liquid, forming a heterogeneous mixture.

Gargles: It is a liquid dosage form containing API in dissolved or suspended in a suitable solvent along with flavourings and other excipients. They specifically designed for gargling.

Lotions: It is a liquid or semi liquid emulsion applied to the skin. The API is dissolved, suspended or dispersed in a base that may include water, oil and emulsifiers.

Liniments: It is an oil based or alcoholic solution containing API along with various excipients such as emollients, penetrants and counterirritants.

Nasal drops: It is a liquid dosage form designed for nasal administration. The API is dissolved or suspended in a sterile saline solution or other suitable vehicle. Nasal drops are used to deliver medication directly to the nasal cavity for the treatment of nasal congestion, allergies, sinusitis or other nasal disorders.

Solutions: It is a homogeneous mixture of one or more active pharmaceutical ingredients dissolved in a liquid solvent. Solutions are typically clear and transparent.

Syrup: It is a concentrated aqueous solution of sugar (sucrose or sugar substitute) in which one or more active pharmaceutical ingredients are dissolved or suspended.

Gaseous dosage forms

Aerosols: It consists of a pressurised container that contains a suspension, solution or dispersion of active pharmaceutical ingredients in a propellant or solvent. When the containers valve is actuated, the contents are released as a fine mist or spray.

Inhalers: It is a type of aerosol dosage form used to deliver medication directly to the lungs through inhalation. They typically consist of a pressurised canister or a dry powder device containing a specific dose of a medication.

Sprays: It typically consists of a pressurised container or pump bottle containing a solution, suspension or dispersion of active pharmaceutical ingredients. The medication is delivered in the form of fine mist or spray.


Dosage forms are the building blocks of medication delivery, which offers variety of options to suit patient needs and treatment goals. From tablets and capsules for easy doing to creams and sprays for targeted relief. Each dosage form serves a unique purpose. Whether it is providing rapid relief with solutions or offering localised treatment with ointments and gels, dosage form plays a crucial role in ensuring effective and convenient medication administration.

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