The pharmaceutical sector continues to evolve rapidly, but the fundamentals of dosage-form design remain indispensable for students and professionals. In recent academic discussions, specialists have emphasized the scientific and practical foundations of tablet technology and liquid oral formulations, both of which form the backbone of modern drug delivery. This article provides an in-depth, curriculum-aligned overview of Unit 2, covering tablet formulation, coating, quality control, and essential aspects of syrups, elixirs, suspensions, and emulsions.
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Understanding Tablets: The Cornerstone of Solid Dosage Forms
Introduction to Tablets
Tablets are solid unit dosage forms prepared by compressing uniform volumes of powdered or granulated materials. They are widely accepted due to their convenience, stability, portability, and precise dosing. Recent reports from pharmaceutical institutes highlight the increasing importance of tablet optimization to meet patient-centric demands.
Ideal Characteristics of Tablets
Experts suggest that an ideal tablet should possess attributes such as mechanical strength, chemical stability, uniformity of dose, rapid disintegration (where required), and patient acceptability. Additionally, tablets must demonstrate resistance to mechanical stress during manufacturing, packaging, and transportation. These characteristics ensure therapeutic effectiveness and safety.
Classification of Tablets
Tablets are categorized based on route of administration and purpose. Common types include compressed tablets, coated tablets, effervescent tablets, chewable tablets, buccal and sublingual tablets, enteric-coated tablets, and modified-release tablets. Each category is designed to meet a specific therapeutic need and release profile.
Formulation of Tablets and the Role of Excipients
Key Excipients Used in Tablets
Excipients form the backbone of tablet formulation. They include diluents to add bulk, binders to impart cohesiveness, disintegrants to promote breakup in the GI tract, lubricants and glidants to ensure smooth tableting, and coloring or flavoring agents to improve patient compliance. Pharmaceutical researchers continue to explore multifunctional excipients to optimize formulation efficiency.
Granulation Methods in Tablet Manufacturing
Granulation converts fine powders into granules to improve flowability and compressibility. The two major techniques are:
Wet Granulation, involving liquid binders to form agglomerates.
Dry Granulation, using pressure (slugging or roller compaction) to form granules without liquids.
Compression and Processing Problems
During compression, manufacturers often encounter defects such as capping, lamination, sticking, picking, or weight variation. These issues typically arise from poor formulation design, improper tooling, or suboptimal processing parameters. Addressing these defects is crucial to ensuring batch uniformity and compliance with regulatory standards.
Equipment and Tablet Tooling
Modern tablet production relies on precision machinery such as single-punch presses, rotary tablet machines, and specialized tooling including punches and dies. These tools determine tablet size, shape, and imprinting, making them vital for product identification and branding.
Tablet Coating: Enhancing Functionality and Stability
Types of Tablet Coating
Coating serves both protective and functional purposes. Major coating types include:
Sugar Coating
Film Coating
Enteric Coating
Compression Coating
Each type offers benefits such as improved appearance, taste masking, controlled drug release, and protection from environmental factors.
Coating Materials and Composition
Formulators use polymers, plasticizers, colorants, and solvents to prepare coating solutions. Film-forming polymers such as HPMC, PVA, and acrylic polymers are widely favored due to their stability and versatility.
Methods and Equipment for Tablet Coating
Common coating techniques include pan coating, air-suspension coating (Wurster process), and fluidized-bed coating. These methods ensure uniform coating deposition and efficient drying. However, coating defects such as cratering, orange peel, blistering, or color variation may occur if process parameters are not optimized.
Quality Control: Ensuring Safety and Efficacy
In-Process Testing
During manufacturing, in-process tests such as weight variation, hardness, friability, and thickness assessments help maintain consistency across batches.
Finished Product Tests
Final tablets must undergo evaluations including disintegration time, dissolution testing, content uniformity, and assay to confirm therapeutic performance. These tests are conducted according to pharmacopoeial standards.
Liquid Orals: Foundations of Syrups, Elixirs, Suspensions, and Emulsions
Formulation and Manufacturing Considerations
Liquid oral dosage forms present unique challenges in terms of solubility, stability, viscosity, and palatability. Syrups require high sugar content to act as a preservative, while elixirs combine alcohol and water to dissolve poorly soluble drugs. Suspensions and emulsions require appropriate stabilizers to maintain dispersed systems and prevent sedimentation or creaming.
Filling, Packaging, and Evaluation
Liquid orals are packaged in airtight, light-resistant containers to maintain stability. Pharmacopoeial standards mandate evaluation parameters such as pH, viscosity, assay, microbial limits, uniformity, and physical stability.