OSFD

Topic Aim

• To understand the development of solid dosage forms (SDFs) and factors affecting their design.

Types of Solid Dosage Forms

• Oral SDFs: Tablets, Capsules, Oromucosal preparations
• Non-Oral SDFs: Rectal preparations, Vaginal preparations

Learning Outcomes

1. Explain the terms ‘solid dosage forms’ and ‘oral solid dosage forms’.
2. Define powders and understand their use in solid dosage preparation.
3. Analyze powder size and understand size reduction methods.
4. Explain methods of particle size separation.
5. Understand powder mixing requirements.
6. Discuss how powder flow characteristics influence SDF preparation.
7. Explain additional components needed for oral solid dosage forms.

Oral Solid Dosage Forms (OSDFs)

• Definition: Medicinal products delivered via the mouth in a solid form for gastrointestinal absorption.
• Common forms include tablets and capsules.

Tablets

• Defined as solid preparations containing a single dose of one or more active ingredients.
• Methods of production: compression, extrusion, moulding, freeze-drying.
• Administration: Can be swallowed whole, chewed, or dissolved before use.

Capsules

• Solid preparations with hard or soft shells containing a single dose of active substances.
• Made by filling one shell with the active ingredient and then closing it.
• Can contain solids, liquids, or paste-like materials.

Powder Characteristics

• Flow: Affects medicine characteristics; powder flow can be positive or negative.
• Factors Affecting Flow:
  • Size
  • Shape
  • Density
  • Material strength

Particle Size Analysis

• Classification:
  • Coarse: >1000 μm
  • Intermediate: >100 μm <1000 μm
  • Fine: >5 μm <100 μm
  • Ultrafine: <5 μm
• Measurement Methods:
  • Light-based methods (microscopy, laser diffraction).
  • Sieving methods (traditional and air jet).
  • Inertial impaction for inhalation products.

Powder Sampling Methods

• Must be representative of bulk material.
• Two methods:
  1. Dynamic: Sampling while powder is in motion.
  2. Static: Sampling when powder is at rest.

Powder Flow

• Cohesive and adhesive forces can impact flow characteristics.
• Adhesion: Chemically dissimilar materials sticking together.
• Cohesion: Chemically similar materials sticking together.
• Flow occurs with an external force and resists below a limit.

Measurement of Powder Flow

1. Angle of Repose: Indicates flow properties; influenced by particle size and moisture.
2. Bulk Density: Density accounting for packing, measured to evaluate flow characteristics.
3. Hausner’s Ratio: Tapped vs. poured bulk density; >1.5 indicates poor flow.
4. Carr's Compression Ratio: Evaluates Cohesion/Cohesion.

Powder Mixing

• Mixing is needed for:
  • Small drug quantities
  • Poor processing characteristics
  • Desired characteristics in the final product.
• Types of Mixing:
  • Diffusion (positive): Homogeneous mixture with no segregation.
  • Density/Size Segregation (negative): Separation based on particle characteristics.
  • Trituration: Mixing using mortar and pestle.

Particle Size Reduction (Comminution)

• Reduces large masses to smaller units mechanically.
• Aids in extraction of APIs and optimizes drug targeting.
• Influences dissolution rate as detailed by Noyes-Whitney equation:\frac{dC}{dt} = \frac{DA( C_s - C )}{h}
• Factors to consider include type of material, intended size distribution, and equipment characteristics.

Excipients

• Non-active compounds that assist in converting APIs to dosage forms by:
  • Bulking up the API
  • Improving stability
  • Enhancing bioavailability
  • Aiding in production processes.
• Most Common Excipients Include:
  • Diluents (e.g., lactose)
  • Binders (e.g., microcrystalline cellulose)
  • Disintegrants (e.g., sodium starch glycolate)
  • Glidants (e.g., fumed silica)
  • Lubricants (e.g., magnesium stearate)
  • Colorants
  • Sweeteners and Flavors.

Conclusion

• Understanding solid dosage forms and their design is crucial for the development and formulation of effective medicinal products.