Classification of Dosage Forms
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Dosage forms are designed to deliver the active pharmaceutical ingredient (API) in a safe, effective, and convenient manner to the patient. The choice of dosage form depends on factors such as the patient's age, medical condition, route of administration, and drug properties.
Dosage forms can be classified on various basis as follows:
1. Classification Based on Physical State:
A. Solid Dosage Forms:
a. Tablets:
- Tablets are the most common solid dosage forms.
- They are prepared by compressing or molding a mixture of the API and excipients.
- Tablets can be uncoated, film-coated, sugar-coated, or enteric-coated based on their intended use and API properties.
- Different types of tablets include immediate-release, extended-release, and effervescent tablets.
b. Capsules:
- Capsules are gelatin shells containing the API in powder, granule, or pellet form.
- They are available as hard gelatin capsules and soft gelatin capsules.
- Capsules provide better API protection and are useful for drugs with an unpleasant taste or odor.
c. Powders and Granules:
- These are fine particles of the API and excipients.
- They can be administered directly or reconstituted into suspensions or solutions for administration.
d. Lozenges and Troches:
- These are solid dosage forms intended to dissolve slowly in the mouth to release the API.
- They are commonly used for local action in the throat and oral cavity.
e. Suppositories:
- Suppositories are solid dosage forms inserted into the rectum or vagina.
- They melt or dissolve at body temperature, releasing the API for systemic or local effects.
2. Liquid Dosage Forms:
a. Solutions:
- Solutions are liquid dosage forms where the API is dissolved in a suitable solvent.
- They provide rapid drug absorption and are suitable for patients who have difficulty swallowing.
b. Suspensions:
- Suspensions are liquid dosage forms where the API is suspended as solid particles in a liquid vehicle.
- The formulation requires shaking before administration to ensure uniform drug distribution.
c. Emulsions:
- Emulsions are liquid dosage forms with immiscible liquids, usually oil and water, stabilized with an emulsifying agent.
- They are used for drugs with poor water solubility and for topical applications.
d. Syrups and Elixirs:
- Syrups are concentrated sugar solutions containing the API.
- Elixirs are sweetened hydroalcoholic solutions containing the API.
- These liquid dosage forms are suitable for pediatric and geriatric patients.
3. Semisolid Dosage Forms:
a. Creams:
- Creams are semisolid dosage forms containing oil-in-water or water-in-oil emulsions.
- They are used for topical application and are easy to spread on the skin.
b. Ointments:
- Ointments are semisolid dosage forms with a greasy or oily base.
- They are used for local application and provide prolonged drug release.
c. Gels:
- Gels are semisolid dosage forms with a jelly-like consistency.
- They are used for topical or ophthalmic applications and provide localized drug delivery.
4. Gaseous Dosage Forms:
a. Aerosols:
- Aerosols are pressurized dosage forms that release the API in the form of fine particles or droplets.
- They are administered through inhalation or nasal routes.
2. Classification Based on Route of Administration:
A. Enteral Dosage Forms:
1. Oral: Dosage forms taken through the mouth, including tablets, capsules, syrups, and solutions.
2. Sublingual and Buccal: Dosage forms placed under the tongue or in the cheek, allowing for direct absorption through the mucosal membrane.
3. Rectal: Suppositories or enemas administered into the rectum for local or systemic effects.
B. Parenteral Dosage Forms:
1. Intravenous (IV): Directly injected into the veins for rapid and complete drug absorption.
2. Intramuscular (IM): Injected into muscle tissue for slower absorption compared to IV but faster than oral.
3. Subcutaneous (SC): Administered into the fatty tissue beneath the skin.
4. Intradermal (ID): Injected into the skin layer, commonly used for allergy testing or tuberculin skin tests.
C. Topical Dosage Forms:
1. Dermal: Applied to the skin surface, including creams, ointments, gels, and patches.
2. Ocular: Formulations for the eyes, such as eye drops or ointments.
3. Nasal: Administered through the nasal route, like nasal sprays.
4. Otic: Applied to the ear, including ear drops or ear ointments.
D. Inhalation Dosage Forms:
1. Oral Inhalation: Medication delivered through inhalers or nebulizers for respiratory conditions.
2. Nasal Inhalation: Dosage forms for local or systemic effects through the nasal cavity.
3. Classification Based on Release Pattern:
A. Immediate-Release Dosage Forms:
These dosage forms release the entire drug dose rapidly after administration, providing an immediate therapeutic effect.
B. Modified-Release (Sustained-Release) Dosage Forms:
1. Delayed-Release: The release of the drug is intentionally delayed until the dosage form reaches a specific part of the gastrointestinal tract.
2. Extended-Release: The drug is released gradually over an extended period, reducing the frequency of dosing.
3. Controlled-Release: Drug release is controlled at a predetermined rate, maintaining a constant drug level in the blood.
4. Classification Based on Packaging:
A. Unit Dose:
Individually packed dosage forms, suitable for single administration.
B. Multi-Dose:
Dosage forms that allow multiple administrations from the same container, like bottles or vials.
5. Classification Based on Function:
A. Therapeutic Dosage Forms:
These dosage forms deliver the active drug for treating a specific medical condition.
B. Diagnostic Dosage Forms:
Dosage forms used for diagnostic purposes, like contrast agents for imaging studies.
C. Prophylactic Dosage Forms:
Dosage forms used to prevent the occurrence of certain medical conditions, like vaccines.
6. Miscellaneous Classification:
A. Radiopharmaceuticals:
Dosage forms containing radioactive isotopes used for diagnostic and therapeutic purposes in nuclear medicine.
B. Ayurvedic Dosage Forms:
Traditional Indian medicine formulations, including churnas, kwaths, and gugguls.
