Lyophilization Of Optimized Batch Case Study

4A.4.2.2 Process Optimization:
The process was optimized for two variables which can make difference in the particle size and further in the stability of emulsion.The process parameters varied were time of stirring and speed of stirring .The results are depicted in Table 4A.11
Process variables:
 Time of stirring: The batches were stirred for different time periods of 30, 45 and 60 minutes, keeping using magnetic stirrer.
 Speed of stirring: The speed of stirring was maintained at400, 600 and 800 r.p.m to check the effect the on particle size.
4A.2.5. Homogenization of Optimized Batches:
In high pressure homogenizer , SLN was forced through a narrow gap at high pressure exposing the product to high shear stress causing formation of very
Lyophilization of Optimized Batches
4A.2.6.1 Selection of cryoprotectant.
Lyophilization is the process of removal of frozen water or solvents from a material through the process of sublimation and the removal of bound water molecules through the process of desorption. The process keeps the product temperature low enough to avoid changes in the dried product appearance and characteristics. Thus it is an excellent method for preserving pharmaceuticals.
The drying process of freeze drying consists of two steps, Primary Drying and Secondary Drying. The bulk of water removed from the product during freeze drying is via sublimation of all of the free ice crystals and organic solvents during the primary drying step which is a slow process conducted at cooler temperatures, safely below the product’s critical temperature. In secondary drying, the water molecules that are bound to the SLN were removed or desorbed at higher temperature without melting or collapse of the product.
The homogenized batches were lyophilized using the Epsilon 2-4A LSC Lyophilizer (Martin Christ) in 32 hours and 4A8 hrs cycles using 2%w/v, 3%w/v and 5%w/v concentrations of cryoprotectants such as mannitol, lactose, galactose and trehalose. The results of visual observations are depicted in table
Evaluation of Solid Lipid Nanoparticles (32 optimized and homogenized batches A and B and lyophilized batches AL and BL):
4A.2.8.1 Appearance:
Batches were checked for their visual appearance.

4A.2.8.2 Determination of pH: pH of the formulations was determined by using Equip-Tronics digital calibrated pH meter.The appearance and pH are depicted in Table 4A.16
4A.2.8.3 Determination of drug content:
Drug content was determined by solubilizing1ml of theformulation in 10 ml of solvent system,methanol:water (90:10), pH adjusted to 3and determined using HPLC analysisusing Table4A.16 depicts the drug content of optimized and lyophilized batches.
4A.2.8.4 Determination of particle size:
Particle size of the formulations was determined byusing Malvern Zetasizer Nano ZS, UK. The instrument uses the principle of dynamic light scattering to measure particle size. This technique measures the diffusion of the particles moving under Brownian motion, and converts this to size and size distribution using the Stoke’s-Einstein relationship. The particle size of the optimized batches was measured after diluting with distilled water while that of the lyophilized batches was determined after dissolving the batch in normal saline.(Nerkar N, Bajaj A,