Osmotic pressure, sterilization by filtration low-molecular povidone

Osmotic pressure, sterilization by filtration (Low-molecular povidone) 

The osmotic pressure of solutions is of particular importance with parenteral administration. (In the case of the human blood serum it is about 7.5 bar at 37 °C.) It is not very affected by the molecular weight and the concentration of povidone. The simplest method for determining the osmotic pressure uses the Van t Hoff equation. 

The osmotic pressure values given in Table 23 were obtained for 10% solutions of low-molecular povidones in water, using the equation given in Table 22. These values apply to pure povidone. As povidone contains only traces of impurities, e.g. 1 ppm vinylpyrrolidone, the osmotic pressure is hardly affected. This is confirmed by comparing the values measured for povidone K 17 with those calculated, in Table 23. The osmotic pressure calculated for a solution containing 1 ppm vinylpyrrolidone is given for reference. 

Product Concentration in water Osmotic pressure (calculated) Osmotic pressure (measured) 

It is important that injection solutions that contain low-molecular povidone can be sterilized by filtration. The feasibility of filtering these solutions is mainly determined by the concentration of these povidone grades. The viscosity evidently plays a subordinate role, as this is always less than 5 mPa s for povidone K17 up to a concentration of 15% in water. With povidone K 12 it is even lower (see Section 2.2.3.1). Taking a batch of Kollidon 17 PF as an example, it can be seen from Fig. 23 that the filtration time depends very much on the concentration. The 

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