Introduction to Pharmaceutical Dosage Form
Drugs are rarely delivered as pure chemical entities but usually provided as prepared formulations known as dosage forms. After converting drugs into an appropriate dose formulation, they are delivered in several dosage forms.
To create alternative dosage forms, non-medicinal chemicals called excipients or pharmaceutical ingredients are added. These excipients help solubilize, suspend, thicken, dilute, emulsify, stabilize, or preserve the drug, making dosage forms more effective and appealing.
Definition of Dosage Form:
- Dosage form is the combination of Active Pharmaceutical Ingredients (API) and excipients in the formulation.
- Dosage forms are the mechanisms by which drug molecules (APIs) are administered to the body to generate maximum intended benefits and minimize unwanted effects.
Need of Dosage Forms:
Dosage forms mainly depend on patient safety and drug safety/benefits:
- Deliver precise dosages safely and easily (e.g., tablets, capsules, syrups).
- Mask bitter taste or odor (e.g., capsules, coated tablets, flavored syrups).
- Allow formulation of insoluble or unstable drugs (e.g., suspensions).
- Provide controlled-release methods for prolonged medication effects (e.g., controlled-release tablets).
- Protect drugs from stomach acid after oral delivery (e.g., enteric-coated tablets).
- Enable topical drug action (e.g., ointments, creams, ear and nasal preparations).
- Allow drug injection into body tissues (e.g., implants).
- Enhance drug delivery via inhalation (e.g., inhalants).
- Provide liquid dosage forms for chemicals soluble in chosen vehicles (e.g., solutions).
- Allow medication introduction into body orifices (e.g., rectal and vaginal suppositories).
- Protect drugs from atmospheric oxygen or moisture (e.g., coated capsules, sealed ampules).
Definition of Drug (Active Pharmaceutical Ingredients):
The term “drug” originated from the old French word “drogue,” meaning dry herb. Drugs are chemical compounds used for diagnosis, prevention, treatment, and management of diseases. They can be chemically synthesized, modified, or biotechnologically produced.
The Active Pharmaceutical Ingredient (API) is the component responsible for the drug’s therapeutic action.
Definition of Excipients:
Excipients are inactive pharmaceutical ingredients with no therapeutic action, such as dyes, preservatives, sweeteners, binding agents, coloring, and flavoring agents.
Classification of Dosage Forms:
Dosage forms are classified based on:
- Physical state or physical form
- Route of administration (ROA)
- Site of action
- Use
1. Classification Based on Physical Form:
Dosage forms include liquid, solid, semi-solid, and gaseous forms.
2. Classification Based on Route of Administration:
Dosage forms vary by how the drug is given to the patient (oral, topical, inhalation, etc.).
3. Classification Based on Site of Action:
Drugs may be classified by where they exert their effect in the body.
4. Classification Based on Use:
Drugs are also classified according to their intended use.
Definitions of Different Dosage Forms
1. Liquid Dosage Forms:
- Droughts: Liquid oral formulations with single or multiple doses.
- Elixirs: Liquids containing excipients and medicaments for oral use.
- Emulsions: Water-based suspensions of oils/fats using emulsifying agents to prevent coalescence.
- Suspensions: Biphasic liquid formulations dispersing active ingredients uniformly when shaken.
- Gargles: Concentrated aqueous solutions applied externally for throat infections.
- Gels: Dispersion in water used commonly as antacids.
- Lotions: External liquid preparations, usually without friction.
- Liniments: External liquids applied with friction.
- Mixtures: Liquid oral preparations containing one or more medications.
- Mouthwashes: Used for oral hygiene and treating infections.
- Nasal drops: Used to treat nasal infections or blockages.
- Solutions: Liquid medicines for internal or external use.
- Syrups: Sweet, viscous liquids with or without sugar and medicaments.
2. Solid Dosage Forms:
- Powders: Micron-sized solid particles.
- Tablets: Solid doses with or without excipients.
- Granules: Groups of particles.
- Capsules: Drugs enclosed in gelatin shells.
- Pills: Small, excipient-containing solid units.
- Lozenges: Sugar or gum-based solids for mouth/throat disorders.
- Suppositories: Solid forms inserted into body cavities like rectum or nose.
3. Semi-solid Dosage Forms:
- Ointments: Semi-solids for external use, with or without medication.
- Creams: Fatty semi-solids with or without medicaments.
- Pastes: Semi-solid with significant powdered medicaments.
- Gels: Transparent or translucent semi-solids with hydrophilic/hydrophobic bases.
4. Gaseous Dosage Forms:
- Sprays: Alcohol-containing aerosols applied to nose or throat.
- Aerosols: Dispersions of solid or liquid particles in gas for respiratory application.
- Inhalations: Pharmaceutical liquids for internal use dispersed in propellants.
Detailed Notes:
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