Polyvinylpyrrolidone /sucrose

PercoU is a polyvinylpyrrolidone-coated silica sol with very low osmolarity. For cell separations therefore the osmolarity is adjusted to isotonic conditions by mixing 9 vol. Percoll stock suspension with 1vol. of 2.5 M sucrose, 1.5 M sodium chloride, or tenfold concentrated cell culture medium (e.g., 10 x RPMl). 

Aso et al. (40) examined the molecular mobility of sucrose and polyvinylpyrrolidone in 1 1 lyophilized mixtures by measuring the spin-lattice relaxation times (7)) of individual carbon atoms by NMR for systems containing residual moisture at varying levels. 7) of the pyrrolidone ring carbon increased with residual moisture for lyophilized PVP alone. However, the mobility of these carbons did not increase with residual moisture when PYP was colyophilized with sucrose. Similarly, the mobility of sucrose did not increase with water activity as much in sucrose/PVP mixtures as much as in sucrose alone. Inhibition of sucrose crystallization by PVP in the presence of water appears to be linked to the effect of PVP on the molecular mobility of sucrose. 

Aso Y, Yoshioka S, Zhang J, Zografi G. Effect of water on the molecular mobility of sucrose and polyvinylpyrrolidone) in a colyophilized formulation as measured by 13C NMR relaxation time. Chem Pharm Bull 2002 50 820-826. 

Zeng, X.M., Martin, G.P., Marriott, C. Effects of molecular weight of polyvinylpyrrolidone on the glass transition and crystallization of co-lyophilized sucrose. Int. J. Pharm. 218, 63-73, 2001... 

Table 2 gives some examples of excipients used as stabilizers for proteins in freeze-dried formulations. Among others, saccharides are the most widely used excipients for stabilizing freeze-dried therapeutic proteins. There are exceptions to the need for stabilizing excipients, e.g., recombinant (ot-Antitrypsin was stable when freeze-dried alone or with lactose, sucrose, and polyvinylpyrrolidone. ... 

Figure 108. Spin-lattice relaxation time of water in aqueous solutions of polymer excipients. , Polyvinylpyrrolidone , gelatin , polyethylene glycol (PEG) 20,000 , PEG400 A, sucrose o, glucose. 7) °, Spin-lattice relaxation time of pure water. (Reproduced from Ref. 460 with permission.)...

Incubate with 2.3 M sucrose or with a mixture of 1.8 M sucrose/20% polyvinylpyrrolidone (PVP) at room temperature for 30-120 min for cryo-protection. 

CH(0CH3)CH2) , polyvinylpyrrolidone (PVP) (-CH(NC4H70)CH2-) satisfy the criteria of NO-NO-NO systems (where N stands for negatively charged oxygen atoms due to its lone pair of electrons and O stands for vacant sites) but do not form intra- or intermolecular H bonds, also exclude Na" salts, sucrose, and glycine. 

If a non-ionized heavy solute, such as sucrose or polyvinylpyrrolidone, is more concentrated at the bottom of a column and the density then decreases continuously towards the top, bands of substances may be intercalated bands of the empty electrolyte, provided the gradient is sufficiently steep and the band concentrations sufficiently low. After completion of electrophoresis, the contents of the column can be emptied into a fraction-collector or through a recording flow photometer, care being taken not to disturb the pattern. 

Uncoated tablet materials, lactose, liquid glucose, mannitol, stearic acid, starch, calcium stearate, talc and sucrose could be tolerated in the precipitation solution without interference. As gelatin and polyvinylpyrrolidone precipitate with sodium tetraphenylboron it is not possible to apply the method to tablets containing these materials. 

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