Pharmaceutics (ER20-11T): Unit 1 - History of Pharmacy, IP & Packaging
Compiled by Prof. Dr. R. K. Mukherjee & Editorial Board
Chapter 1: Introduction to Dosage Forms
Dosage forms are the means (or physical form) by which drug molecules are delivered to sites of action within the body to achieve maximum therapeutic effect and minimum adverse reaction.
1.1 Need for Dosage Forms
- Protection: To protect the active drug substance from destructive atmospheric oxygen or moisture (e.g., coated tablets, sealed ampoules).
- Gastric Protection: To protect the drug substance from destruction by gastric acid after oral administration (e.g., enteric-coated tablets).
- Taste & Odor Masking: To mask the bitter, salty, or offensive taste or odor of a drug substance (e.g., capsules, flavored syrups).
- Controlled Drug Delivery: To provide rate-controlled drug action over an extended period (e.g., sustained-release or transdermal patches).
1.2 Classification of Dosage Forms
Dosage forms are primarily classified according to their physical state and route of administration:
| Physical State | Solid | Semisolid | Liquid | Gaseous |
|---|---|---|---|---|
| Unit Dosage | Tablets, Capsules, Pills, Cachets | Suppositories, Pessaries | Ampoules, Single-dose drops | Metered Dose Inhalers (MDI) |
| Bulk / Multi-dose | Dusting powders, Dentifrices, Effervescent granules | Ointments, Creams, Pastes, Gels | Syrups, Elixirs, Emulsions, Suspensions | Aerosols, Inhalations, Sprays |
Chapter 2: Packaging Materials in Pharmacy
Pharmaceutical packaging is defined as the art and science of enclosing or protecting medical products for distribution, storage, sale, and use.
2.1 Types of Glass Containers
Glass is predominantly composed of silicon dioxide with varying amounts of soda ash, limestone, and alumina:
Type I: Highly Resistant Borosilicate Glass
Possesses the highest chemical resistance and lowest thermal expansion coefficient. Used primarily for parenteral preparations (injections, aqueous infusions), buffered solutions, and blood products.
Type II: Treated Soda-Lime Glass
De-alkalized through sulfur dioxide treatment at high temperature. Suitable for neutral or acidic aqueous parenteral preparations.
Type III: Regular Soda-Lime Glass
Moderate chemical resistance. Suitable for non-aqueous parenterals, dry powders for injection, and oral liquid preparations.
Type NP: General Purpose Soda-Lime Glass
Intended strictly for non-parenteral applications (oral syrups, topical ointments, tablets).
Chapter 3: Size Reduction & Separation
Size reduction (Comminution) is the process of reducing large solid pharmaceutical materials into smaller particles.
3.1 Mechanisms of Size Reduction
- Impact: Material is hit by an instantaneous blow (e.g., Hammer Mill).
- Attrition: Breaking down particle edges through friction and shear between surfaces (e.g., Fluid Energy Mill).
- Compression: Material is crushed between two rigid surfaces under steady force (e.g., Roller Mill).
- Cutting: Sharp blades cut fibrous or elastic vegetable drugs into specified segments (e.g., Cutter Mill).
Chapter 4: Mixing and Homogenization
Mixing is an operation in which two or more separate ingredients are treated so that each particle of any one ingredient lies as nearly adjacent as possible to a particle of each of the other ingredients.
4.1 Planetary Mixer
In a planetary mixer, the mixing blade revolves on its own axis while simultaneously orbiting the center of the stationary mixing bowl. This double planetary motion eliminates dead zones and ensures uniform distribution of granulating liquids into dry powder blends.
4.2 Silverson Emulsifier
Operates by high shear rotor-stator action. Emits centrifugal force that drives the immiscible liquid phases through a perforated stator head, breaking oil droplets down to 0.5 - 2 microns.
Chapter 5: Clarification and Filtration
Filtration is the physical process of separating suspended solids from a liquid or gas by passing the fluid through a porous medium that retains the particulate matter.
5.1 Poiseuille's Law & Darcy's Equation
\[ V = \frac{K \cdot A \cdot \Delta P}{\eta \cdot l} \]
Where:
- V: Rate of filtration
- K: Permeability coefficient of the filter cake
- A: Surface area of the filtering medium
- ΔP: Pressure differential across the filter
- η: Dynamic viscosity of the filtrate
- l: Cake thickness