Determination of polyvinylpyrrolidone using high-performance liquid chromatography

Polyvinylpyrrolidone (PVP) is a versatile polymer with innate surface activity. It is very difficult to accurately assay due to its wide molecular weight range and amphiphilic nature. This study evaluated a reversed-phase HPLC method to separate and quantify PVP K15. The assay used a Hicrome C18 150 mm x 3 microm HPLC column in combination with an 80/20 propanol-1-ol: deionised water, 0.01% TFA mobile phase, which resolved the polymer as a single peak, tR = 10.69+/-0.17 min (n=120) at 243 nm. The column's performance was constant throughout the study, N (theoretical plates) = 1729+/-22 and the peak symmetry remained good (As ranged from 0.74 to 0.92, n=10 over the calibration range). The developed assay proved to be accurate, sensitive and capable of recovering PVP K15 from pharmaceutical formulations. The limits of quantification and detection were calculated statistically as 2.40 and 0.72 mg ml(-1), respectively. Assay reproducibility assessed at five concentrations gave an average coefficient of variance <3.5% and the accuracy of the analytical method was 102.62+/-2.04%. The recovery of PVP K15 from directly compressed tablets and Refresh eye drops was 98.02+/-2.73 and 108.35+/-6.52%, respectively.

A molecular dynamics simulation of reactant mobility in an amorphous formulation of a peptide in poly(vinylpyrrolidone)

The reaction pathways available for chemical decomposition in amorphous solids are determined in part by the relative mobilities of the potential reactants. In this study, molecular dynamics simulations of amorphous glasses of polyvinylpyrrolidone (PVP) containing small amounts of water, ammonia, and a small peptide, Phe-Asn-Gly, have been performed over periods of up to 100 ns to monitor the aging processes and associated structural and dynamic properties of the PVP segments and embedded solutes. Glass transition temperatures, Tg, were detected by changes in slopes of the volume-temperature profiles and the internal energy-temperature profiles for the inherent structures upon cooling at different rates. Analyses of the molecular trajectories below Tg reveal both temporal and spatial heterogeneity in polymer and solute mobility, with each molecule or part of a molecule displaying quite different relaxation behaviors for translational, rotational, and/or conformational motions. Rotations of individual polymer segments on the time scale up to 100 ns, though far from complete, are described by the Kohlrausch-Williams-Watts stretched exponential function with relaxation times tau on the order of 10-2.8 x 10(4) micros at an averaged stretching parameter beta of 0.39. The rotation rates are, on the average, faster for the side chains and for segments near the ends of the chains than for the backbones and segments near the middle of the chains. In contrast to their behavior in water, solute diffusive motions in the glassy polymer exhibit non-Einsteinian behavior over the time scale of the simulations characterized by two types of motion: (1) entrapments within relatively fluid microdomains surrounded by a matrix of relatively immobile polymer chains; and (2) jumps between microdomains with greater probability of hopping back to the solute's previous location. The average jump length and frequency are highly dependent on solute size, being much smaller for the tripeptide, Phe-Asn-Gly, than for water and ammonia. The diffusivities of water and ammonia, solutes capable of forming hydrogen bonds with the lactam residues within the polymer segments, are significantly reduced by strong electrostatic interactions. The conformational preferences of Phe-Asn-Gly were compared in the amorphous polymer and water to detect differences in the degree to which the tripeptide may be predisposed toward deamidation of the asparagine side chain in these environments. Although only minor differences are evident in peptide conformation, the conformational dynamics for the peptide embedded in the glassy polymer are characterized by a higher energy barrier between conformational states and 2.5-44-fold larger relaxation times for the dihedral angles of interest than in water. However, in the context of peptide deamidation, these differences may be of secondary importance in comparison to the more than two to three orders of magnitude reduction in the diffusivities of water, ammonia, and the tripeptide in PVP.

Evaluation of β-lactose, PVP K12 and PVP K90 as excipients to prepare piroxicam granules using two wet granulation techniques

The present investigation aimed at evaluating the use of different excipients, beta-lactose and polyvinylpyrrolidone of two molecular weights (PVP K12 and PVP K90), in the production of improved release piroxicam granules, by wet granulation using both water and steam as granulation liquid. The formulations examined were: piroxicam (Px)/beta-lactose; Px/PVP K12 and Px/PVP K90, each one at a 1:9 weight ratio. The most significant difference between beta-lactose and PVP is that, using the first excipient, both steam and water granules were produced while, when PVP were employed, only steam granules were obtained. Image analysis revealed that beta-lactose steam granules had a larger surface area with respect to water granules, whereas lower values of this parameter were observed in PVP-s granules, confirming the Scanning Electron Microscopy micrographs and the fractal analysis results. As regards the enhancement of the dissolution profiles, the best result was obtained using beta-lactose steam granules followed by PVP K12 ones, even if the reactive dimension values indicated that during the dissolution process PVP K12 granules modified the surface more than beta-lactose granules. As regards PVP K90, this excipient was the one less influencing the granule morphology and the dissolution behaviour. Differential Scanning Calorimetry analysis suggested the partial amorphisation of the drug in the granules containing the three excipients. This result was then confirmed by X-ray powder diffraction analysis. Therefore, beta-lactose and PVP K12 could be proposed as useful excipients to enhance the dissolution rate of Px from granules prepared using the steam granulation technique.

Combination of SEC/MALS experimental procedures and theoretical analysis for studying the solution properties of macromolecules

Size-exclusion chromatography (SEC) with dual detection, i.e., employing refractive index (RI) and multiangle light-scattering (MALS) detectors, has been applied to study the solution properties of two very different polymer-solvent systems at 25 degrees C: poly(N-vinylcarbazole) (PVCz) in an organic solvent THF that is a very good solvent and a system under theta conditions that is formed by polyvinylpyrrolidone (PVP) in water containing a 0.1 M concentration of NaNO(3). In both cases, the analysis of a single highly polydisperse sample obtained by free radical polymerization is enough for obtaining molecular weight and radius of gyration calibration curves, molecular weight distributions (MWD) (and thus, molecular weight averages), molecular dimensions, scaling laws coefficients and unperturbed dimensions. Extrapolation to theta conditions produces values of the characteristic ratio of the unperturbed dimensions C(n)=<r(2)>(o)/nl(2)=15.9 and 14, respectively, for PVCz and PVP. Unperturbed dimensions are also theoretically calculated with different models such as Kuhn equivalent chain, worm-like chain and rotational isomeric states model. Conformational parameters required for this last model were taken from the literature in the case of PVCz; however, they are calculated by molecular dynamics simulations in the case of PVP. Theoretical values obtained with the RIS model are in good agreement with the experimental results.

Reaction of a peptide with polyvinylpyrrolidone in the solid state

During stability studies at high temperature (70 degrees C) and low relative humidity ( approximately 0%), the recovery of an asparagine containing hexapeptide (VYPNGA) and its known deamidation products from solid polyvinylpyrrolidone (PVP) matrices was incomplete. To determine the causes of this mass loss, formulations were prepared by lyophilizing solutions containing PVP, glycerol, and the Asn-hexapeptide in pH 7.5 phosphate buffer, followed by storage at 70 degrees C and 0% relative humidity. Asn-hexapeptide loss was mono-exponential and reached a plateau at about 30% remaining. Total recovery of the peptide and its known deamidation products was approximately 30% of peptide load. Size exclusion chromatography with fluorescence detection indicated the formation of a PVP-peptide adduct that was stable in the presence of 6 M guanidine hydrochloride. Similar stability studies using N-acetyl phenylalanine, phenylalanine ethyl ester, and N-acetyl tyrosine ethyl ester demonstrated that the reaction involves the peptide N-terminus. The adduct was disrupted in the presence of carboxypeptidase-A, suggesting the formation of an amide bond between the peptide and PVP. (15)N solid-state nuclear magnetic resonance spectroscopy using (15)N-labeled valine as a model of the peptide N-terminus showed different populations of (15)N, suggesting that noncovalent peptide-polymer interactions precede amide bond formation.

[Do polyvinylpyrrolidone (PVP) deposits still occur in internal organs at the turn of the millennium? Observations on three patients from the former USSR]

PVP had been used as a plasma expander following the end of world war II up to relatively recently but after its intracellular storage became known, it was withdrawn from use. Nevertheless, it was used as a retarding agent for subcutaneous and intramuscular administration of drugs until the 1980s and as a consequence pseudotumors have been observed. Three patients from the former USSR are described with PVP storage in the gastric and duodenal mucosa as well as in lymph nodes. The reason for the administration in these patients and the substances applied remain obscure. It is known that PVP infusions are still performed in Taiwan and that it was also injected intraarticularly as an artificial joint lubricant in Russia in the early 1990s. Because cells with intracytoplasmic deposits of PVP can be misdiagnosed as tumor cells and for reasons of general health - "la maladie polyvinylique" [1] may develop - it is still necessary to retain knowledge of the histology of cellular PVP storage.

Recalcitrance of poly(vinylpyrrolidone): evidence through matrix-assisted laser desorption-ionization time-of-flight mass spectrometry

The aerobic biodegradability of an extensively used synthetic polymer was monitored the first time on a laboratory-scale fixed-bed bioreactor (FBBR) applying matrix-assisted laser desorption-ionization time-of-flight mass spectrometry (MALDI-TOF MS). Polymeric poly(vinylpyrrolidone) (PVP) was spiked at concentrations of 10 mg l(-1) onto the FBBR run with river water and the biodegradation monitored after lyophilization of aliquots of the test liquor applying MALDI-TOF-MS. The latter proved to be a powerful tool for qualitative screening purposes of PVP in a molecular mass range <20 kDa in particularly yielding a high sensitivity and shot-to-shot reproducibility. The sample-to-sample reproducibility was enhanced applying the anchor target device. Post-source decay-MALDI-TOF-MS fragmentation investigations determined the unknown end groups of PVP unambiguously. Poor biodegradability of PVP can be assumed, since even after 30 days, no oxidation of the terminal groups and no difference in the repeating units was observed. A decrease in the molecular mass distribution can be drawn back rather to adsorption of PVP in the FBBR other than to biodegradation. This was further investigated performing an adsorption experiment with sewage sludge as solid matrix and analyses of the aqueous phase and sludge samples. Extrapolating these results to the situation in wastewater treatment plants, it is highly likely that PVP is eliminated from the dissolved phase by adsorption onto sludge particles.

Qualitative determination of polyvinylpyrrolidone type by near-infrared spectrometry

Soluble polyvinylpyrrolidones are very useful and versatile pharmaceutical auxiliaries. The different types of povidone are characterised by their viscosity measured in water, expressed as a K-value. We have developed a rapid, accurate, reliable, and non-destructive near infrared (NIR) spectroscopy method for the determination of PVP type and consequently identification thereof. We have implemented chemometrics onto NIR spectra collected in diffuse reflectance mode using fibre optics to build a qualitative model that enables us to obtain useful analytical information. A principal component analysis and a modelling technique soft independent modelling of class analogy (SIMCA) were applied. An approach to validate the method was developed.

Quantitative analysis of povidone (PVP) in drug-PVP matrix using multicomponent analysis

A method for the quantification of povidone (PVP), in solid dispersions and physical mixtures of the polymer and a very slightly soluble drug substance, has been developed by multicomponent analysis using the concepts of chemometrics. Because the UV-absorbance spectra of PVP is completely overlapped by the UV-absorbance spectra of the drug substance, a direct spectrophotometric method of PVP is impossible. However, UV-spectrophotometric data were analyzed by the Quant + Perkin Elmer software for quantitative multicomponent analysis using chemometrics, and by the optimal method developed using a solvent of pH 7.4, a fast, reliable, and precise detection of PVP was obtained when the content of PVP in the powder sample exceeded 20% (m/m). Two methods were developed by the calibration procedure, using buffers of pH 7.4, respectively pH 8.5. By applying a solvent of pH 8.5, more sample could be taken into use because of the enhanced solubility of the drug substance, and hence it was believed that as more PVP was taken into use, a better prediction of PVP would be obtained. However, as more drug substance was taken into use the UV-absorbance spectrum of PVP was even more overlapped, and an inferior prediction was obtained.

'Mucoid dissolution' of bones and multiple pathologic fractures in a patient with past history of intravenous administration of polyvinylpyrrolidone (PVP). A case report

Polyvinylpyrrolidone (PVP) has been used in industry as well as in medicine for various purposes, e.g. as a component of hair-sprays, 'retardant' for subcutaneous injections, and given intravenously as a plasma expander. The latter usage results in deposition of PVP in the reticulo-endothelial system and other mesenchymal cells, including osteocytes. A middle aged woman in Taiwan, who for 10 years received repeated intravenous injections of PVP, suffered pathologic fractures of both femora and her right humerus with additional destructive lesions seen radiologically in other bones. Biopsies of the fracture sites showed both intracellular PVP deposits and mucoid changes in the involved cells, a characteristic secondary complication of PVP deposition. This phenomenon, if of sufficient severity, may cause, as in this case, a virtual 'melting down' of osseous tissue with pathological fractures as a consequence.

Ultrastructure, protein synthesis and secretion of day-6 rabbit blastocysts cultured in a chemically defined, protein-free medium

Day-6 rabbit blastocysts were cultured in Ham's F10 medium supplemented with polyvinylpyrrolidone as a macromolecular component, for 4 to 12 h. The integrity of the blastocyst cells was demonstrated by electron microscopy. Expansion and biosynthesis of proteins and of DNA were studied after culturing in the presence of 35S-methionine and 3H-thymidine. Polyvinylpyrrolidone did not interfere with the subsequent protein analysis, which was performed by two dimensional gel electrophoresis followed by silver staining and fluorography. More than 600 labelled proteins were found in the blastocyst tissue, many of them were also present in the blastocyst fluid and in the blastocyst coverings. Several proteins seemed to be produced for incorporation into the blastocyst coverings; others, only detected in the culture medium, might have been synthesized for secretion into the environment.

The relationship between the glass transition temperature and water vapor absorption by poly(vinylpyrrolidone)

Water associated with amorphous solids is known to affect significantly the physical and chemical properties of dosage form ingredients. An analysis of water vapor absorption isotherms of poly(vinylpyrrolidone) measured in this and other laboratories, over the range -40 to 60 degrees C, along with the measurement of the glass transition temperature of poly(vinylpyrrolidone) as a function of water content is reported. It is observed that the amount of water vapor absorbed at a particular relative humidity increases with decreasing temperature, along with a significant change in the shape of the isotherm. It is also shown that at any temperature, along with a significant change in the shape of the isotherm. It is also shown that at any temperature the state of the solid changes from a highly viscous glass to a much less viscous rubber in the region where absorbed water appears to enter into a "solvent-like" state. Further, the apparent "tightly bound" state, observed at low relative humidities, appears to exist when the polymer enters into a very viscous glassy state. It is concluded that the apparent states of water and polymer are interrelated in a dynamic manner and, therefore, that they cannot be uncoupled by simple thermodynamic analyses based only on a water-binding model.

The interaction of papain with polycations

An investigation has been made of the interactions of the enzyme papain with the polycations protamine, polybrene, poly(L-lysine), spermine, spermidine and the neutral polymer polyvinylpyrrolidone (PVP). At low concentrations, each behaves as an inhibitor of the enzyme. As their concentrations increased above a certain level, the activity of the systems increased, and their inhibition of the enzyme appeared to be less pronounced. When acting by themselves in the presence of the substrate haemoglobin, each of the polycations was a weak proteolytic catalyst with a ranking of catalytic effectiveness of protamine greater than polybrene greater than poly(L-lysine) greater than polyvinyl-pyrrolidone greater than spermidine greater than spermine. This effect could explain the anomalous inhibition of papain by these polycations. The interaction of papain with dansyl protamine (DNSP) and the extent of complex formation were studied using a fluorescence polarization technique and the results showed that there was a strong interaction occurred. The strength of binding was assessed by determination of the critical electrolyte concentration (0.2 M, NaNO3). The stoichiometry of the DNSP-papain complex was found to be 63 base moles of DNSP to one mole of papain.

[Preparation and testing of polymer drugs. 4. Water-soluble polymer drugs with a base of vinylpyrrolidone-maleic acid anhydride-copolymers]

Watersoluble polymeric drugs were synthesized on the basis of alternating copolymer of 1-vinyl-2-pyrrolidone and maleic anhydride. Benzocain served as model drug. The drug was bound directly as well as about epsilon-aminocapronic acid as spacer. The pancreatin catalyzed hydrolysis of these polymeric drugs was studied. No hydrolysis was noted, if the drug is directly bound on the copolymer. The polymeric drug with the epsilon-aminocapronic acid as spacer showed a small release. Possible reasons for these facts are discussed.

Interaction of povidone with aromatic compounds. VI: Use of partition coefficients (log Kd) to correlate with log P values and apparent Kd values to express the binding as a function of pH and pKa

The binding of neutral aromatic compounds onto povidone was studied. It was found that the binding depends on the lipophilic character of the compound and that a linear free relationship exists between the logarithm of the partition coefficients of the macromolecular pseudo-two-phase-aqueous phase, and the log partition coefficient of n-octanol-water (log P). For the ionized ligand molecules it was shown that the binding could be expressed in terms of the acid dissociation constant of the solute, Ka, and in terms of two partition coefficients, K1 = HAPVP/HAwater and K2 = APVP/Awater for the nondissociated and dissociated forms, respectively, resulting in the apparent partition coefficient Kdapp = (HAPVP + APVP)/(HAwater + Awater). An expression was derived, permitting one to determine K1 and K2 from measurable quantities. The apparent partition coefficients (Kdapp) were independent of both drug and povidone concentrations, indicating that the modes of povidone compound interactions were essentially invariant over the ranges of systematic variables studied. The method provides a simple means of evaluating ligand-macromolecule interaction as a function of pH of the solvent and pKa of the ligand.

Square-wave voltammetric determination of acetaldehyde in povidone

A rapid, precise, and accurate method is described for the determination of acetaldehyde in povidone (polyvinyl pyrrolidone). The sample is dissolved in a basic aqueous electrolyte and analyzed using square-wave voltammetry. The proposed method allows for direct measurement of acetaldehyde under gentle conditions, thus avoiding loss of analyte due to volatility of acetaldehyde. The method is specific for acetaldehyde in the presence of other aldehydes and povidone process impurities.

Chemical and microbiologic characteristics and toxicity of povidone-iodine solutions

The chemical, microbiologic, and toxic characteristics of povidone-iodine solution, a commonly used antiseptic agent, are addressed in a collective review of relevant works published from 1956 to the present. Interactions of this agent with the thyroid gland and the kidneys and its toxicity at the cellular and systemic level are discussed.

Intracellular mucoid changes in tumor cells of meningiomas: a manifestation of polyvinylpyrrolidone (PVP) effect on tissues with mesenchymal characteristics

In two cases of meningiomas in Taiwanese patients, extensive intracellular mucoid changes were found within tumor cells, together with deposits of polyvinylpyrrolidone (PVP) granules. Both patients had in the past received intravenous PVP as a plasma expander. Recipients of PVP have previously been reported to develop a form of PVP thesaurismosis with concomitant mucoid changes in the cells storing this substance. Such changes, as a rule, were limited to cells of mesenchymal origin. By storing PVP granules and undergoing mucoid changes as a result, meningioma tumor cells behave as cells with mesenchymal characteristics.