JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD B. Pharmacy III Year INDUSTRIAL PHARMACY-I Previous Question Paper (September-2021 - R17)

Particle size is a critical physical property that significantly influences the performance, stability, and manufacturing efficiency of solid dosage forms. Its importance is categorized as follows:

• Dissolution and Bioavailability: According to the Noyes-Whitney equation, dissolution rate is directly proportional to the surface area. Reducing particle size increases the surface area, which enhances the dissolution rate of poorly water-soluble drugs, thereby improving oral bioavailability.
• Content Uniformity: In low-dose drug formulations, uniform particle size distribution is essential to ensure that each dosage unit contains the same amount of active pharmaceutical ingredient (API), preventing segregation during blending and compression.
• Flow Properties: Particle size and shape dictate the flowability of powders. Fine particles often exhibit poor flow due to inter-particulate friction, whereas larger, granular particles flow better, ensuring consistent die filling during tablet compression.
• Stability: Smaller particles may increase the susceptibility of the drug to chemical degradation due to increased surface area exposure to moisture or atmospheric oxygen.
• Manufacturing Efficiency: Particle size affects the compressibility and compactability of powders, influencing the hardness and friability of the final tablet.

Polymorphism is the ability of a solid material to exist in more than one crystalline form or structure. These polymorphs have the same chemical composition but differ in their internal crystal lattice arrangement, leading to distinct physical and chemical properties.

In an industrial setup, the significance of polymorphism is paramount:

• Solubility and Bioavailability: Different polymorphs exhibit varying lattice energies. A metastable form typically has higher solubility and faster dissolution rates compared to a stable form, which can be exploited to enhance the bioavailability of BCS Class II drugs.
• Stability: The stable polymorph is thermodynamically favored and less likely to undergo phase transformation during storage. Conversely, metastable forms may convert to stable forms over time, potentially leading to precipitation or changes in dissolution profiles, which affects shelf-life.
• Manufacturing Performance: Polymorphs often possess different crystal habits (e.g., needle-like, plate-like). This affects bulk density, flowability, and compressibility, which can cause significant issues during granulation and tableting if the crystal form is not strictly controlled.
• Regulatory and Patent Implications: Since different polymorphs can be patented as distinct entities, pharmaceutical companies must characterize the polymorphic form of their API to ensure patent protection and regulatory compliance. Analytical techniques such as X-ray powder diffraction (XRPD), Differential Scanning Calorimetry (DSC), and Infrared Spectroscopy are essential for routine quality control to identify and quantify polymorphic purity.