Evaluation of the Stability of Bacteriophages in Different Solutions Suitable for the Production of Magistral Preparations in Belgium

In Belgium, the incorporation of phages into magistral preparations for human application has been permitted since 2018. The stability of such preparations is of high importance to guarantee quality and efficacy throughout treatments. We evaluated the ability to preserve infectivity of four different phages active against three different bacterial species in five different buffer and infusion solutions commonly used in medicine and biotechnological manufacturing processes, at two different concentrations (9 and 7 log pfu/mL), stored at 4 °C. DPBS without Ca²⁺ and Mg²⁺ was found to be the best option, compared to the other solutions. Suspensions with phage concentrations of 7 log pfu/mL were unsuited as their activity dropped below the effective therapeutic dose (6–9 log pfu/mL), even after one week of storage at 4 °C. Strong variability between phages was observed, with Acinetobacter baumannii phage Acibel004 being stable in four out of five different solutions. We also studied the long term storage of lyophilized staphylococcal phage ISP, and found that the titer could be preserved during a period of almost 8 years when sucrose and trehalose were used as stabilizers. After rehydration of the lyophilized ISP phage in saline, the phage solutions remained stable at 4 °C during a period of 126 days.

Can adjuncts to bowel preparation for colonoscopy improve patient experience and result in superior bowel cleanliness? A systematic review and meta-analysis

BACKGROUND

Bowel preparation for colonoscopy is often poorly tolerated due to poor palatability and adverse effects. This can negatively impact on the patient experience and on the quality of bowel preparation. This systematic review and meta-analysis was carried out to assess whether adjuncts to bowel preparation affected palatability, tolerability and quality of bowel preparation (bowel cleanliness).

METHODS

A systematic search strategy was conducted on PubMed, MEDLINE, EMBASE and the Cochrane Database of Systematic Reviews to identify studies evaluating adjunct use for colonoscopic bowel preparation. Studies comparing different regimens and volumes were excluded. Specific outcomes studied included palatability (taste), willingness to repeat bowel preparation, gastrointestinal adverse events and the quality of bowel preparation. Data across studies were pooled using a random-effects model and heterogeneity assessed using I2-statistics.

RESULTS

Of 467 studies screened, six were included for analysis (all single-blind randomised trials; n = 1187 patients). Adjuncts comprised citrus reticulata peel, orange juice, menthol candy drops, simethicone, Coke Zero and sugar-free chewing gum. Overall, adjunct use was associated with improved palatability (mean difference 0.62, 95% confidence interval 0.29-0.96, p < 0.001) on a scale of 0-5, acceptability of taste (odds ratio 2.75, 95% confidence interval: 1.52-4.95, p < 0.001) and willingness to repeat bowel preparation (odds ratio 2.92, 95% confidence interval: 1.97-4.35, p < 0.001). Patients in the adjunct group reported lower rates of bloating (odds ratio 0.48, 95% confidence interval: 0.29-0.77, p = 0.003) and vomiting (odds ratio 0.47, 95% confidence interval 0.27-0.81, p = 0.007), but no difference in nausea (p = 0.10) or abdominal pain (p = 0.62). Adjunct use resulted in superior bowel cleanliness (odds ratio 2.52, 95% confidence interval: 1.31-4.85, p = 0.006). Heterogeneity varied across outcomes, ranging from 0% (vomiting) to 81% (palatability), without evidence of publication bias. The overall quality of evidence was rated moderate.

CONCLUSION

In this meta-analysis, the use of adjuncts was associated with better palatability, less vomiting and bloating, willingness to repeat bowel preparation and superior quality of bowel preparation. The addition of adjuncts to bowel preparation may improve outcomes of colonoscopy and the overall patient experience.

Historical Evolution and Provider Awareness of Inactive Ingredients in Oral Medications

PURPOSE

A multitude of different versions of the same medication with different inactive ingredients are currently available. It has not been quantified how this has evolved historically. Furthermore, it is unknown whether healthcare professionals consider the inactive ingredient portion when prescribing medications to patients.

METHODS

We used data mining to track the number of available formulations for the same medication over time and correlate the number of available versions in 2019 to the number of manufacturers, the years since first approval, and the number of prescriptions. A focused survey among healthcare professionals was conducted to query their consideration of the inactive ingredient portion of a medication when writing prescriptions.

RESULTS

The number of available versions of a single medication have dramatically increased in the last 40 years. The number of available, different versions of medications are largely determined by the number of manufacturers producing this medication. Healthcare providers commonly do not consider the inactive ingredient portion when prescribing a medication.

CONCLUSIONS

A multitude of available versions of the same medications provides a potentially under-recognized opportunity to prescribe the most suitable formulation to a patient as a step towards personalized medicine and mitigate potential adverse events from inactive ingredients.

Phycocosmetics and Other Marine Cosmetics, Specific Cosmetics Formulated Using Marine Resources

Marine resources exist in vast numbers and show enormous diversity. As a result, there are likely many possible applications for marine molecules of interest in the cosmetic industry, whether as excipients or additives, but especially as active substances. It is possible to obtain extracts from active substances; for example, quite a few algae species can be used in moisturizing or anti-ageing products. In the field of topical photoprotection, mycosporine-like amino acids and gadusol are important lines of enquiry that should not be overlooked. In the field of additives, the demonstration that certain seaweed (algae) extracts have antimicrobial properties suggests that they could provide alternatives to currently authorized preservatives. These promising leads must be explored, but it should be kept in mind that it is a long process to bring ingredients to market that are both effective and safe to use.

A Novel Approach to Optimize Hot Melt Impregnation in Terms of Amorphization Efficiency

In this study, an innovative methodology to optimize amorphization during the hot melt impregnation (HMI) process was proposed. The novelty of this report revolves around the use of thermal analysis in combination with design of experiments (DoEs) to reduce residual crystallinity during the HMI process. As a model formulation, a mixture of ibuprofen (IBU) and Neusilin was used. The main aim of the study was to identify the critical process parameters of HMI and determine their optimal values to assure a robust impregnation process and possibly the highest possible amorphization rate of IBU. In order to realize this, a DoE approach was proposed based on a face-centered composite design involving three factors. The IBU/Neusilin ratio, the feeding rate, and the screw speed were considered as variables, while the residual crystallinity level of IBU, determined using differential scanning calorimetry (DSC), was measured as the response. Additionally, the stability of IBU under HMI was analyzed using high-performance liquid chromatography to estimate the extent of potential degradation. In order to verify the correctness of the DoE model, tested extrudates were manufactured by HMI and the obtained extrudates were thoroughly examined using scanning electron micrography, X-ray powder diffraction, and DSC.

Exudate gums: chemistry, properties and food applications - a review

Gums are complex carbohydrate molecules which have the ability to bind water and form gels at low concentration. These carbohydrates are often associated with proteins and minerals in their structure. Gums are of various types such as seed gums, exudate gums, microbial gums, mucilage gums, seaweeds gums, etc. Exudate gums are plant gums which ooze out from bark as a result of a protection mechanism upon injury. Exudate gums have been used by humans since ancient times for various applications due to their easy availability. The main characteristics which make them fit for use in various applications are viscosity, adhesive property, stabilization effect, emulsification action and surface-active property. Major applications of these gums are in food products, the paper, textile, cosmetics and pharmaceutical industries, oil-well drilling, etc. In the present paper, the chemistry, properties, processing and applications of commercially available exudate gums such as acacia gum or gum arabic, karaya gum, ghatti gum and tragacanth gum are discussed. Recent literature reveals that apart from the above mentioned applications, these gums also have nutritional properties which are being explored. Other gums cannot replace them because of their certain unique characteristics. © 2020 Society of Chemical Industry.

Esters of terpene alcohols as highly potent, reversible, and low toxic skin penetration enhancers

Skin penetration/permeation enhancers are compounds that improve (trans)dermal drug delivery. We designed hybrid terpene-amino acid enhancers by conjugating natural terpenes (citronellol, geraniol, nerol, farnesol, linalool, perillyl alcohol, menthol, borneol, carveol) or cinnamyl alcohol with 6-(dimethylamino)hexanoic acid through a biodegradable ester linker. The compounds were screened for their ability to increase the delivery of theophylline and hydrocortisone through and into human skin ex vivo. The citronellyl, bornyl and cinnamyl esters showed exceptional permeation-enhancing properties (enhancement ratios up to 82) while having low cellular toxicities. The barrier function of enhancer-treated skin (assessed by transepidermal water loss and electrical impedance) recovered within 24 h. Infrared spectroscopy suggested that these esters fluidized the stratum corneum lipids. Furthermore, the citronellyl ester increased the epidermal concentration of topically applied cidofovir, which is a potent antiviral and anticancer drug, by 15-fold. In conclusion, citronellyl 6-(dimethylamino)hexanoate is an outstanding enhancer with an advantageous combination of properties, which may improve the delivery of drugs that have a limited ability to cross biological barriers.

Use of Terahertz-Raman Spectroscopy to Determine Solubility of the Crystalline Active Pharmaceutical Ingredient in Polymeric Matrices during Hot Melt Extrusion

Polymer-based amorphous solid dispersions (ASDs) comprise one of the most promising formulation strategies devised to improve the oral bioavailability of poorly water-soluble drugs. Exploitation of such systems in marketed products has been limited because of poor understanding of physical stability. The internal disordered structure and increased free energy provide a thermodynamic driving force for phase separation and recrystallization, which can compromise therapeutic efficacy and limit product shelf life. A primary concern in the development of stable ASDs is the solubility of the drug in the polymeric carrier, but there is a scarcity of reliable analytical techniques for its determination. In this work, terahertz (THz) Raman spectroscopy was introduced as a novel empirical approach to determine the saturated solubility of crystalline active pharmaceutical ingredient (API) in polymeric matrices directly during hot melt extrusion. The solubility of a model compound, paracetamol, in two polymer systems, Affinisol 15LV (HPMC) and Plasdone S630 (copovidone), was determined by monitoring the API structural phase transitions from crystalline to amorphous as an excess of crystalline drug dissolved in the polymeric matrix. THz-Raman results enabled construction of solubility phase diagrams and highlighted significant differences in the solubilization capacity of the two polymer systems. The maximum stable API-load was 20 wt % for Affinisol 15LV and 40 wt % for Plasdone S630. Differential scanning calorimetry and XRPD studies corroborated these results. This approach has demonstrated a novel capability to provide real-time API-polymer phase equilibria data in a manufacturing relevant environment and promising potential to predict solid-state solubility and physical stability of ASDs.

Antisolvent precipitation technique: A very promising approach to crystallize curcumin in presence of polyvinyl pyrrolidon for solubility and dissolution enhancement

Curcumin with a vast number of pharmacological activities is a poorly water soluble drug which its oral bioavailability is profoundly limited by its dissolution or solubility in GI tract. Curcumin could be a good anticancer drug if its solubility could be increased. Therefore, the aim of the present study was to increase the dissolution rate of curcumin by employing antisolvent crystallization technique and to investigate the effect of polyvinyl pyrrolidone K30 (PVP) as colloidal particles in crystallization medium on resultant particles. Curcumin was crystalized in the presence of different amounts of PVP by antisolvent crystallization method and their physical mixtures were prepared for comparison purposes. The samples were characterized by scanning electron microscopy (SEM), differential scanning calorimetry (DSC), X-ray powder diffraction (XRPD) and Fourier transform infrared spectroscopy (FT-IR). The solubility and dissolution of the treated and untreated curcumin were also determined. Antisolvent crystallization of curcumin led to the formation of particles with no definite geometric shape. It was interesting to note that the DSC and XRPD studies indicated the formation of a new polymorph and less crystallinity for particles crystallized in the absence of PVP. However, the crystallized curcumin in the presence of PVP was completely amorphous. All crystalized curcumin samples showed much higher dissolution rate compared to untreated curcumin. The amount of curcumin dissolved within 10 for treated curcumin in the presence of PVP (1:1 curcumin:PVP) was 7 times higher than untreated curcumin and this enhancement in the dissolution for curcumin samples crystallized in the absence of PVP was around 5 times. Overall' the results of this study showed that antisolvent crystallization method in the absence or presence of small amounts of PVP is very efficient in increasing the dissolution rate of curcumin to achieve better efficiency for curcumin.

OPTIMIZATION OF THE PREPARATION OF KOLLIDON SR-BASED AMIODARONE HYDROCHLORIDE TABLETS WITH SUSTAINED RELEASE

AIM

The formulation of sustained release tablets of AMD-HCl using KOLLIDON SR as matrix-forming agent. Chitosan, a natural polysaccharide with superior hydrating and absorbing properties was used in the formulation stage to optimize the release characteristics of those matrix tablets.

MATERIAL AND METHODS

Nine formulations of sustained release matrix tablets of AMD x HCl (200 mg/tablet) were prepared through direct compression. The concentrations of matrix forming agents were included as independent variables of a type 2(3) mixed factorial plan in order to develop formulations of AMD-HCl with optimal release characteristics. The dependent variables of that plan were the amount of AMD released from the tablets studied by using in vitro dissolution testing. The test was carried out in the paddle apparatus II for 12 hours in two pH media that were relevant to oral delivery: 2 hours at pH 1.2 and 10 hours at pH 6.8. The released AMD-HCl was quantitatively determined through a validated HPLC method.

RESULTS

The increase in KOL concentration leads to a decrease in AMD release rate at both pH values. The use of CHT resulted in a decrease of AMD release only at pH 6.8 in formulations with the lowest concentration of KOL.

CONCLUSIONS

The retarding effect on the release of AMD-HCl in the tablets developed in this study was directly proportional to the KOL concentration in the formulation.

Plaque triclosan concentration and antimicrobial efficacy of a new calcium carbonate toothpaste with 0.3% triclosan compared to a marketed 0.3% triclosan toothpaste

OBJECTIVE

To compare the delivery and retention of triclosan in dental plaque, and to compare the antibacterial efficacy of a newly developed toothpaste to a marketed calcium carbonate toothpaste.

METHODS

Two clinical delivery/retention studies were carried out to determine the concentration of triclosan in plaque 10 minutes, and two and four hours after brushing with a new triclosan-containing toothpaste with magnesium aluminium silicate or a marketed triclosan-containing toothpaste. Both studies had a double-blind, randomized, complete cross-over design. Supragingival plaque samples (minimum 2 microg) were taken from smooth surfaces of all teeth (1-7) in all four quadrants for the 10-minute plaque measurements and in two randomly allocated quadrants at the two- and four-hour time points. Triclosan concentration was measured by HPLC. Antibacterial efficacy was evaluated in vitro using a biofilm formation approach. Three replicate experiments were carried out to check for repeatability and consistency of the assay. Toothpaste slurries were prepared by stirring one part by weight of each toothpaste with two parts by weight of deionized water. An overnight culture suspension of Streptococcus mutans (ATCC 25175) was prepared and then adjusted to give a bacterial count of approximately 10(7) CFU/ml. Sterile HAP discs were used as substrate and treated with the toothpaste slurry before inoculation with the standardized culture suspension of S. mutans. Following incubation in brain heart infusion (BHI) broth containing 2% sucrose for four hours, standard Total Viable Count (TVC) procedures were carried out and colonies counted (log10 values).

RESULTS

Brushing with the new calcium carbonate/triclosan toothpaste resulted in a higher triclosan concentration in plaque after 10 minutes, and two and four hours compared to a marketed triclosan toothpaste. The increase ranged from 14% to 35% and was statistically significant (p < 0.05). The antibacterial efficacy of the new calcium carbonate/triclosan toothpaste, measured four hours after application, was greater than that of a marketed toothpaste with 0.3% triclosan. The difference was statistically significant (p < 0.05).

CONCLUSION

The new calcium carbonate toothpaste with 0.3% triclosan and magnesium aluminium silicate demonstrated significantly greater efficacy four hours post-brushing both in terms of in vivo delivery and in vitro antibacterial action compared to a marketed calcium carbonate toothpaste with 0.3% triclosan.

In vitro and in vivo evaluation of novel osmotic pump tablets of isosorbide-5-mononitrate containing polyvinyl pyrrolidone (PVP) for controlled release

A novel osmotic pump tablet with ethyl cellulose (EC) and polyvinyl pyrrolidone (PVP) as the semipermeable membrane and isosorbide-5-mononitrate (5-ISMN) as the model drug was formulated in this study. Zero order release kinetics were attained by avoiding aging during storage. Drug release increased with an increase in the percentage of PVP K30 in the semipermeable membrane. However, drug release decreased with increased coating weight. Drug release rates decreased continuously for tablets coated with EC/PEG4000 and cellulose acetate (CA)/PEG4000. This tendency was more marked with longer storage time. However, there was little change in drug release rates for tablets with a semipermeable membrane of EC/PVP K30 at 6, 12 or 24 months. The weight loss test also validated the results mentioned above. The relative bioavailability of the osmotic-pump tablets against the reference formulation in single and multiple dose regimens was 116.7 and 106.5, respectively. This means that the bioavailability of osmotic pump tablets using PVP as the plasticiser was equal to that of the reference formulation. In general, 5-ISMN osmotic pump tablets with a semipermeable membrane composed of EC/PVP K30 may be useful in providing constant drug delivery with minimum fluctuations during longer storage time.

Formulation and in vivo evaluation of sodium alendronate spray-dried microparticles intended for lung delivery

Spray-dried powders for lung delivery of sodium alendronate (SA) were prepared from hydroalcoholic solutions. Formulations display geometric particle size below to 12 μm and spherical shape associated to a hollow structure. The addition of leucine and ammonium bicarbonate leads to porous particles with rough surfaces. The tapped density ranges from 0.016 to 0.062 g/cm(3), decreasing with the increase of the leucine concentration. For all formulations, the calculated aerodynamic diameters are lower than 5 μm. The in vitro aerodynamic evaluation shows that all powders present a high emitted fraction of 100%, a fine particle fraction ranging from 34.4% to 62.0% and an alveolar fraction ranging from to 23.7% to 42.6%. An optimized sample was evaluated regarding sodium alendronate acute pulmonary toxicity and lung bioavailability. The bronchoalveolar lavage study shows that the intratracheal administration of sodium alendronate dry powder and sodium alendronate aqueous solution do not induce significant increases of lung toxicity indicators as compared with the positive control. Moreover, the intratracheal administration of sodium alendronate dry powder results in a 6.23 ± 0.83% bioavailability, a 3.5-fold increase as compared to oral bioavailability. Finally, these results suggest that sodium alendronate pulmonary delivery could be a new and promising administration route.

[On teaching the chemistry of pharmaceutical auxiliary substances within the framework of pharmaceutical education in the Czech and Slovak Republics]

The paper emphasizes the need of the introduction of the subject Chemistry of Pharmaceutical Auxiliaries into the Pharmacy study programme at more colleges in the Czech and Slovak Republics. It also introduces and discusses some topics for possible extension of the content of the courses of the subject (the presented examples are taken form the field of analytical chemistry of pharmaceutical auxiliaries).

Release kinetics of basic fibroblast growth factor (bFGF) from certain biopolymers in the presence of ketoprofen

The aim of the present study was the evaluation of basic fibroblast growth factor (bFGF, FGF-2) release in vitro from four types of polymer bases (carriers), fibrin, microcrystalline chitosan (MCCh), fibrin and MCCh, as well as MCCh and methylcellulose (MC) in the presence or absence of ketoprofen (KTA). Amount of released basic fibroblast growth factor was measured immunoenzymatically using Elisa (R&D System). Ketoprofen concentration was determined spectrophoto-metrically at 255 nm, using an appropriate absorbance factor, alpha 1 cm (1%) = 662. The most significant influence of ketoprofen on bFGF release was seen in the case of microcrystalline chitosan carrier elution. Parameters of the equation which describe the amount of bFGF released from chitosan carrier with and without KTA are y = 6.842 +/- 1.637 In(t) + 14.935 +/- 2.378, determination coefficient, R2 = 0.9332 and y = 4.070 +/- 0.622 In(t) + 10.589 +/- 1.011, determination coefficient, R2 = 0.9606. The time after which 20% of bFGF was released (t 20%) in the presence of ketoprofen was 2.1 h whereas it was significantly longer without ketoprofen (10.1 h). The amount of bFGF released from fibrin carrier was lower in the presence of ketoprofen. The time taken for 20% of bFGF to be released (t 20%) was very long (41.7h) in the presence of KTA and 16.3 h. without KTA. The other carriers (fibrin + MCCh and MCCh + MC) in the presence of ketoprofen appear to have an insignificant influence on the kinetics of basic fibroblast growth factor release. For the chitosan carrier (p = 0.05, and also p = 0.01, when t(theoret) = 2.921), there is a statistically significant difference between the coefficients (a1 and a2) of the regression equation describing the process of basic fibroblast growth factor release from the base with and without ketoprofen. It was also found that the amount of ketoprofen released varied considerably according to the carrier. All results clearly indicate that the type of carrier not only has an impact on the amount of bFGF released, but also on the kinetics of ketoprofen release.

The use of the Modified Gingival Margin Plaque Index (MGMPI) method to investigate the inhibitory effect of various toothpastes on dental plaque formation

OBJECTIVE

Colgate Total (CTT) is the only FDA-approved toothpaste for antiplaque and antigingivitis benefits. The objective of this study was to compare the impact of Colgate Total Pharma (CTP), a new variant of Colgate Total, with Colgate Regular Toothpaste (CRT) on plaque formation over a 24-hour period following a single use of the dentifrice.

METHODS

CTP and CRT were the two test products. CRT was used for a washout product as well. Fifteen male/female subjects who met the inclusion/exclusion criteria were included into this single-blind (preliminary phase) and double-blind (randomized phase) crossover study. Ethical approval and written informed consent were obtained. Preliminary phase: After a one-week washout with CRT, subjects brushed in the dental clinic with CRT before a one-minute use of a test dentifrice. A baseline Modified Gingival Margin Plaque Index (MGMPI) score was calculated. Subjects refrained from oral hygiene for 24 hours, and returned to the clinic for their 24-hour MGMPI score. Subjects entered the second washout phase to repeat as per the crossover design. The above procedures were conducted three times by three independent examiners. Randomized phase: Subjects were randomized to the groups according to a computer-generated randomization schedule. The procedure was carried out as in the preliminary phase, except the washout period between the two products was at least one week and the products (CTP or CRT) were used in a randomized double-blind manner. Plaque scores were recorded as above.

RESULTS

CTP provided a significant (p = 0.01) antiplaque effect versus CRT. The results are consistent with previously reported data for CTT. All three examiners demonstrated a strong correlation for this clinical study utilizing the MGMPI methodology.

CONCLUSION

This clinical investigation examined the efficacy of a new variant of a commercial dentifrice, historically shown to provide antiplaque and antigingivitis efficacy. It is important to confirm the continued efficacy of new products to consumers and to the profession. Additionally, this clinical trial demonstrated the usefulness of the clinical methodology with respect to consistency in results by three independent clinical examiners. Because this methodology is often employed to document antiplaque benefits of new and existing technologies, it is important to periodically evaluate and confirm its reliability and reproducibility.

Oral insulin delivery using nanoparticles based on microemulsions with different structure-types: optimisation and in vivo evaluation

The purpose of this study was to optimise entrapment of insulin in poly(alkylcyanoacrylate) nanoparticles prepared from microemulsions with different microstructure containing isopropyl myristate, caprylocaproyl macrogolglycerides, polyglyceryl oleate and insulin solution and to investigate the in vitro release and bioactivity of insulin in nanoparticles dispersed in the microemulsion templates. Entrapment efficiency and release of insulin were studied using a reverse-phase HPLC assay. Morphology of the nanoparticles was examined with scanning electron microscopy. Bioactivity of insulin was studied using a streptozotocin-diabetic rat model. Nanoparticles were spherical with 200-400 nm in size without significant difference between different microemulsion templates, types and amounts of monomer. Entrapment efficiency increased significantly with increasing monomer concentration but decreased with increasing aqueous fraction in the microemulsion template. Insulin loading however, showed an opposite trend. In vitro release profiles of insulin from the nanoparticles dispersed in the microemulsion templates were controlled by the monomer concentration only. In vivo, a consistent and significant hypoglycemic effect over controls was found for up to 36 h depending on the type of monomer. No significant serum insulin levels were detectable. This study showed that the strategy of delivering insulin orally, entrapped in nanoparticles and dispersed in a biocompatible microemulsion is promising and highlights the importance of optimisation studies in combination with in vivo experiments.

Co-relationship of physical stability of amorphous dispersions with enthalpy relaxation

Physical stability studies of valdecoxib (VLB) and its solid dispersions with PVP (1, 2, 5, 10, 15 and 20% w/w) were carried out by Differential Scanning Calorimetry (DSC). Change in specific heat with time was measured to determine the degree of crystallinity of amorphous drug and its binary dispersions after storage at 40 degrees C and 75% RH. The rate of crystallization was found to decrease with increasing PVP concentration and time for 10% crystallization (t90%) was found to increase significantly for the amorphous drug when formulated as PVP dispersions. Enthalpy relaxation was found to be inversely correlated with t90% (min) values and was found to be a good predictor of devitrification tendency and hence stability of amorphous VLB.

Determination of betulinic acid from Orthosiphon stamineus leaf extract in rat plasma

A simple high-performance liquid chromatography (HPLC) method to determine the content of betulinic acid (BA) in rat plasma collected at different times (0-8 h) after oral administration of Orthosiphon stamineus leaf extract was developed. The features of the assay include protein precipitation using acetonitrile and isocratic elution using reverse phase C-18 column with ultraviolet (UV) detection. The recovery of BA from plasma varied from 98.4 to 102.5%. The R.S.D of intra- and inter-day precision from rat plasma ranged from 4.2 to 9.8%. The maximum concentration of BA in the plasma was 1.2 +/- 0.3 microg/ml at 1 h after oral administration of the extract.

[Preparation of Zhongjiefeng dispersible tablets]

OBJECTIVE

To prepare Zhongjiefeng dispersible tablets.

METHODS

The formulation of Zhongjiefeng dispersible tablets were optimized as index of disintegration time by orthogonal design test.

RESULTS

The optimized Zhongjiefeng dispersible tablets, which were prepared by selecting 16% PVPP and 3% L-HPC as disintegrants, 40% MCC as filler, can disintegrate in 3 mins.

CONCLUSIONS

The above formulation is reasonable and the disintegration time is suitable, so it can provide theoretic support for industrialization.

How to make hypericin water-soluble

Hypericin, isolated from Hypericum perforatum, is an effective photodynamic substance as demonstrated by various studies. Practical forms of applications of hypericin solutions for systemic use and introduction into body cavities are, however, lacking. We developed an aqueous solution of hypericin non-covalently bound to polyvinylpyrrolidone (PVP). PVP is a poly-N-vinylamide of various degrees of polymerization and forms of intermolecular crosslinks suitable for diagnostic and therapeutic applications. We used PVP (molecular weights of PVP between 10 kD and 40 kD) as a complex forming agent to prepare hypericin for photodynamic therapy and diagnostics. In pure water, hypericin forms aggregates which are non-soluble and non-fluorescent. The hypericin-PVP complex binds more than 1000 mg of hypericin in presence of 100 g PVP or less and is soluble in 1 liter of pure water. Aqueous complex solutions of hypericin-PVP display a characteristic absorption spectrum and fluorescence emission band around 600 nm wavelength. Varying concentrations of hypericin do not cause a blue- or red-shift in the absorption maximum at 595 nm. Excitation at 200 nm to 500 nm leads to emission at 590 nm; a property conducive to diagnostic investigations both in vitro and in vivo. Furthermore, hypericin-PVP exhibits high photostability in the presence of oxygen and broad band light which ensures reproducible photodynamic therapy and diagnosis.

CONCLUSION

Hypericin forms liquid molecular chromophore complexes in water when bound to PVP thus allowing investigations in biological media.

Particle design of poorly water-soluble drug substances using supercritical fluid technologies

In order to improve the dissolution properties of poorly water-soluble drugs, some drugs were subjected to micronization or prepared as composite particles using supercritical fluid (SCF) technology with carbon dioxide (CO(2)). Solubility in CO(2) is the key when using this method. Solubility affects the supersaturation of the materials in the solvent as well as the mass transfer of that solvent, which are both critical to the micronization of the materials and the formation of the composite particles. Some useful techniques that can be used to avoid the problems posed by the characteristics of the drug itself are combining SC-CO(2) with other technologies, such as the formation of coacervates or emulsions, and other equipment types, such as milling or ultrasound fields. Another advantage of SCF technology is that it is considered to be green chemistry. SC-CO(2) can improve the solubility of poorly water-soluble drug substances using few or no organic solvents and with little or no heating.

Room temperature ionic liquids and their mixtures: potential pharmaceutical solvents

Room temperature ionic liquids (RTILs) are organic salts which are liquids at ambient temperature. Composed of relatively large asymmetric organic cations and inorganic or organic anions, they have generated interest as 'green' solvents. Here we report on the solvency of alkyl imidazolium salts (PF(6)(-)Br(-)Cl(-)) for poorly water-soluble model drugs, albendazole and danazol, indicating their potential application as pharmaceutical solvents/cosolvents. The solubility of albendazole, for example, is increased by more than 10,000 times by 1-butyl-3-methylimidazolium hexafluorophosphate ([bmim]PF(6)(-)). Ionic liquids can be water-miscible or water-immiscible. The aqueous miscibility of a poorly water-miscible RTIL such as of [bmim]PF(6)(-) can be improved by the inclusion of a second more miscible RTIL (e.g. 1-hexyl-3-methylimidazolium bromide ([hmim]Br(-))). The extent of improvement in water miscibility was found to correlate with the hydrophilicity of the second RTIL. This ability to modulate RTILs' aqueous miscibility increases their usefulness as pharmaceutical solvents.

Dual effects of Tween 80 on protein stability

In this paper, we used IL-2 mutein as a model protein and evaluated the effect of Tween 80, a non-ionic surfactant. In summary, we found that the dual effects of Tween 80 on the stability of IL-2SA, such as that shaking-induced aggregation of IL-2 mutein was significantly inhibited in the presence of Tween 80. However, this surfactant adversely affected the stability of IL-2 mutein in solution during storage in terms of both oxidation and aggregation. These adverse effects are strongly temperature and formulation-dependent. Data particularly showed that IL-2 mutein in solution forms soluble aggregates to a different degree in different formulations during storage at 40 degrees C for 2 months. Aggregation was barely detectable during storage at 5 degrees C for 22 months. Addition of 0.1% Tween 80 significantly increased the rate of IL-2 mutein aggregation during storage. The IL-2 mutein aggregates are linked by both disulfide and non-disulfide bonds and their relative contribution is temperature-dependent. IL-2 mutein can be oxidized also to a different degree in different formulations during storage and the oxidation rate is strongly temperature-dependent with an activation energy between 21 and 25 kcal/mol. Addition of 0.1% Tween 80 not only increased the rate of oxidation in general but also altered the temperature-dependency of IL-2 mutein oxidation.

The impact of a medium molecular weight, low molar substitution hydroxyethyl starch dissolved in a physiologically balanced electrolyte solution on blood coagulation and platelet function in vitro

BACKGROUND AND OBJECTIVES

Hydroxyethyl starches (HES) may have the potential to impact negatively on haemostasis. Recent findings suggest that side-effects on haemostasis stem not only from the physicochemical differences between HES, but also from the composition of the solvent. We compared the effects of a newly developed medium molecular weight (MW) and low molar substitution (MS) HES dissolved in a physiologically balanced electrolyte solution (MW 130, MS 0.42; B-HES) with a commercially available non-balanced HES (MW 130, MS 0.4; NB-HES), and with Ringer's lactate (RL) solution in vitro.

MATERIALS AND METHODS

Activated partial thromboplastin time (APTT), factor VIII clotting activity (F VIII:C) and von Willebrand factor (vWF) activity were investigated in 48 healthy individuals. Platelet function as measured by turbidimetric platelet aggregometry and whole blood impedance aggregometry induced by adenosine diphosphate (ADP), collagen and thrombin receptor activating peptide (TRAP), and by ADP and TRAP-induced expression of activated platelet fibrinogen receptor glycoprotein (GP) IIb/IIIa was determined in 24 participants. Haemodilution (25% and 50%, v/v for blood coagulation analyses and 20% and 40%, v/v for platelet function studies) was performed using the two HES preparations and RL.

RESULTS

APTT was significantly longer and F VIII and vWF significantly lower at 25% and 50% dilutions with NB-HES compared to B-HES and RL. At 20% and 40% dilutions, ADP and TRAP-induced expression of activated platelet surface GP IIb/IIIa was significantly increased by B-HES compared to NB-HES and RL. Percentages of platelet GP IIb/IIIa expression were also significantly greater in samples diluted with B-HES than in undiluted blood. Neither the diluent (B-HES, NB-HES and RL) nor the degree of dilution (undiluted, 20% and 40% dilution) had any significant influence on ADP, collagen or TRAP-induced turbidimetric platelet aggregation or impedance platelet aggregation.

CONCLUSIONS

In contrast to a non-balanced 130 kDa, MS 0.4 HES (NB-HES), a 130 kDa, MS 0.42 HES preparation dissolved in a physiologically balanced electrolyte solution (B-HES) does not affect APTT, F VIII:C and vWF in vitro. Both types of HES do not affect platelet aggregation induced by ADP, collagen or TRAP. B-HES but not NB-HES increases the expression of activated platelet GP IIb/IIIa induced by ADP or TRAP.

Design and in vivo evaluation of a patch delivery system for insulin based on thiolated polymers

PURPOSE

The aim of this study was to develop and evaluate a novel three-layered oral delivery system for insulin in vivo.

METHODS

The patch system consisted of a mucoadhesive layer, a water insoluble backing layer made of ethylcellulose and an enteric coating made of Eudragit. Drug release studies were performed in media mimicking stomach and intestinal fluids. For in vivo studies patch systems were administered orally to conscious non-diabetic rats. Orally administered insulin in aqueous solution was used as control. After the oral administration of the patch systems a decrease of glucose and increase of insulin blood levels were measured.

RESULTS

The mucoadhesive layer, exhibiting a diameter of 2.5mm and a weight of 5mg, comprised polycarbophil-cysteine conjugate (49%), bovine insulin (26%), gluthatione (5%) and mannitol (20%). 74.8+/-4.8% of insulin was released from the delivery system over 6h. Six hours after administration of the patch system mean maximum decrease of blood glucose level of 31.6% of the initial value could be observed. Maximum insulin concentration in blood was 11.3+/-6.2ng/ml and was reached 6h after administration. The relative bioavailability of orally administered patch system versus subcutaneous injection was 2.2%.

CONCLUSION

The results indicate that the patch system provides enhancement of intestinal absorption and thereby offers a promising strategy for peroral peptide delivery.

Spherical crystals of celecoxib to improve solubility, dissolution rate and micromeritic properties

Celecoxib spherical agglomerates were prepared with polyvinylpyrrolidone (PVP) using acetone, water and chloroform as solvent, non-solvent and bridging liquid, respectively. The agglomerates were characterized by differential scanning calorimetry (DSC), X-ray diffraction (XRD), IR spectroscopic studies and scanning electron microscopy (SEM). The IR spectroscopy and DSC results indicated the absence of any interactions between drug and additives. XRD studies showed a decrease in crystallinity in agglomerates. The crystals exhibited significantly improved micromeritic properties compared to pure drug. The loading efficiency (% or mg drug per 100 mg crystals) was in the range of 93.9 +/- 2.3 and 97.3 +/- 1.3% (n = 3) with all formulations. The aqueous solubility and dissolution rate of the drug from crystals was significantly (p < 0.05) increased (nearly two times). The solubility and in vitro drug release rates increased with an increase in PVP concentration (from 2.5 to 10%). The SEM studies showed that the crystal posseses a good spherical shape with smooth and regular surface.

Improving the compaction properties of roller compacted calcium carbonate

The effects of roller compaction process parameters, morphological forms of calcium carbonate and particle size of sorbitol on flow, compaction and compression properties were investigated. The morphology of the calcium carbonate and the sorbitol particle size were more influential on the compaction properties than the settings of the roller compactor. The roller compaction process was demonstrated to be robust and stable in regard to flowability and compactibility. The flowability of the granules was improved adequately to facilitate compression in a production scale rotary tablet press. By adding sorbitol to the calcium carbonate, the compressibility - characterized by the Walker coefficient W(ID) - and the compactibility C(P) were improved considerably. A correlation between the consolidation characteristics was demonstrated. Compactibility data from the compaction simulator correlated with the tablet press for two of the calcium carbonates, the cubic form and the ground quality.

The influence of povidone K17 on the storage stability of solid dispersions of nimodipine and polyethylene glycol

Previous studies revealed that solid dispersions containing nimodipine and polyethylene glycol 2000 can be effectively prevented from recrystallization by adding povidone K17. These systems are characterized by a high dissolution rate and a remarkable supersaturation of the drug in the dissolution media. It is still unknown if these characteristics are achievable with all polyethylene glycol and povidone mixtures. The objective of the present study is to find out, whether povidone K17 has to be dissolved in melted polyethylene glycol during the preparation process of solid dispersions by the melting method in order to avoid recrystallization of the drug and to ensure storage stability. Solid dispersions consisting of 20% (m/m) nimodipine, 16% (m/m) povidone K17 and 64% (m/m) of six different mixtures of polyethylene glycol 2000 and 8000 were prepared by the melting method and investigated by dissolution testing, thermal analysis and X-ray diffraction. As the solubility of povidone K17 in polyethylene glycol 2000 is about 70% at 65 degrees C and decreases with increasing molecular weight of the polyethylene glycol, mixtures containing different amounts of dissolved povidone K17 are obtained by varying the mixing ratio of polyethylene glycol 2000 and 8000. Recrystallization is inhibited in the formulations, containing mainly polyethylene glycol 2000 whereas recrystallization occurs in systems consisting predominantly of polyethylene glycol 8000. These results show clearly that dissolution of povidone in melted polyethylene glycol is a prerequisite in order to prevent recrystallization.

[Preparation and stability investigation of gastrodin dispersible tablets]

To prepare and optimize the gastrodin dispersible tablets by orthogonal design using the disintegration time as index. The quality of gastrodin dispersible tablets was evaluated by the initial stability test. The results showed that the disintegration time of optimized prescription formulation was 106s, i.e. L-HPC and CMS-Na was used by combining exterior and interior and the dissolution percent in vitro was obviously super to the conventional tablets. Moreover, the quality of the dispersible tablets was very well by stability test.

Coupling Between Chemical Reactivity and Structural Relaxation in Pharmaceutical Glasses

PURPOSE

To test the hypothesis that the molecular motions associated with chemical degradation in glassy amorphous systems are governed by the molecular motions associated with structural relaxation. The extent to which a chemical process is linked to the motions associated with structural relaxation will depend on the nature of the chemical process and molecular motion requirements (e.g., translation of a complete molecule, rotational diffusion of a chemical functional group). In this study the chemical degradation and molecular mobility were measured in model systems to assess the degree of coupling between chemical reactivity and structural relaxation. The model systems included pure amorphous cephalosporin drugs, and amorphous molecular mixtures containing a chemically labile drug and an additive expected to moderate molecular mobility.

METHODS

Amorphous drugs and mixtures with additives were prepared by lyophilization from aqueous solution. The physical properties of the model systems were characterized using optical microscopy and differential scanning calorimetry. The chemical degradation of the drugs alone and in mixtures with additives was measured using high-performance liquid chromatography (HPLC). Molecular mobility was measured using isothermal microcalorimetry to measure enthalpy changes associated with structural relaxation below T (g).

RESULTS

A weak correlation between the rates of degradation and structural relaxation times in pure amorphous cephalosporins suggests that reactivity in these systems is coupled to molecular motions in the glassy state. However, when sucrose was added to one of the cephalosporin drugs stability improved even though this addition reduced T (g) and the relaxation time constant, tau(D)(beta), suggesting that there was no correlation between reactivity and structural relaxation in the cephalosporin mixtures. In contrast, the rate of ethacrynate sodium dimer formation in mixtures was more strongly coupled to the relaxation time constant, tau(D)(beta).

CONCLUSIONS

These studies suggest that the extent to which chemical degradation is coupled to structural relaxation in glasses motions is determined by how closely the motions of the rate controlling step in chemical degradation are associated with structural relaxation. Moderate coupling between the rate of dimer formation for ethacrynate sodium in mixtures with sucrose, trehalose and PVP and structural relaxation constants suggests that chemical changes that require more significant molecular motion, and includes at least some translational diffusion, are more strongly coupled to the molecular motions associated with structural relaxation. The observation that sucrose stabilizes cefoxitin sodium even though it lowers T (g) and reduces the relaxation time constant, tau(D)(beta) is perhaps a result of the importance of other kinds of molecular motions in determining the chemical reactivity in glasses.

Theoretical and Practical Approaches for Prediction of Drug–Polymer Miscibility and Solubility

PURPOSE

Crystallization of drugs formulated in the amorphous form may lead to reduced apparent solubility, decreased rate of dissolution and bioavailability and compromise the physical integrity of the solid dosage form. The purpose of this work was to develop thermodynamic approaches, both practical and theoretical, that will yield a better understanding of which factors are most important for determining the ability of polymers to stabilize amorphous active pharmaceutical ingredients (API).

MATERIALS AND METHODS

Lattice based solution models were used to examine miscibility criteria in API-polymer blends. Different methods were used to estimate the Flory-Huggins interaction parameter for model API-polymer systems consisting of felodipine or nifedipine with poly(vinylpyrrolidone) (PVP). These were melting point depression and determination of solubility parameters using group contribution theory. The temperature and enthalpy of fusion of crystalline API alone and the fusion temperature of the API in the presence of the polymer were measured by differential scanning calorimetry. The resultant thermal data were used to estimate the reduced driving force for crystallization and the solubility of the API in the polymer.

RESULTS

Flory-Huggins theory predicts that, for typical API-polymer systems, the entropy of mixing is always favorable and should be relatively constant. Due to the favorable entropy of mixing, miscibility can still be achieved in systems with a certain extent of unfavorable enthalpic interactions. For the model systems, interaction parameters derived from melting point depression were negative indicating that mixing was exothermic. Using these interaction parameters and Flory-Huggins theory, miscibility was predicted for all compositions, in agreement with experimental data. A model was developed to estimate the solubility of the API in the polymer. The estimated solubility of the model APIs in PVP is low suggesting that kinetic rather than thermodynamic stabilization plays a significant role in inhibiting crystallization.

CONCLUSIONS

The thermodynamics of API-polymer systems can be modeled using solution based theories. Such models can contribute towards providing an understanding of the compatibility between API and polymer and the mechanisms of physical stabilization in such systems.

A Comparison of the Physical Stability of Amorphous Felodipine and Nifedipine Systems

PURPOSE

The objective of this study was to investigate thermodynamic and kinetic factors contributing to differences in the isothermal nucleation rates of two structurally related calcium channel blockers, nifedipine and felodipine, both alone and in the presence of poly(vinylpyrrolidone) (PVP).

MATERIALS AND METHODS

Thin films of amorphous systems were cast onto glass slides and the nucleation rate was determined using optical microscopy. Enthalpy, entropy, and free energy of crystallization of the pure compounds were measured using differential scanning calorimetery (DSC). Molecular mobility and glass transition temperature of each amorphous system were characterized using DSC and hydrogen bonding patterns were analyzed with infrared spectroscopy. The composition dependence of the thermodynamic activity of the amorphous drug in the presence of the polymer was estimated using Flory-Huggins lattice theory.

RESULTS

Nifedipine crystallized more readily than felodipine from the metastable amorphous form both alone and in the presence of PVP despite having a similar glass transition temperature and molecular mobility. Nifedipine was found to have a larger enthalpic driving force for crystallization and a lower activation energy for nucleation.

CONCLUSIONS

The properties of the metastable form alone did not explain the greater propensity for nifedipine crystallization. When considering the physical stability of amorphous systems, it is important to also consider the properties of the crystalline counterpart.

The hydrophilic-coated inflatable penile prosthesis: 1-year experience

INTRODUCTION

Penile prosthesis infections are a devastating complication for both patient and surgeon. Efforts to reduce the risk of infection from these elective procedures are a major focus of research and development by the major prosthesis companies. The Titan inflatable penile prosthesis (Mentor Corporation, Santa Barbara, CA) is coated with polyvinylpyrrolidone (PVP), a hydrophilic substance that reduces bacterial adherence and absorbs and elutes the antibiotics the device is immersed in intraoperatively. The Titan device was introduced to the American market in September 2002. This study reports the 1-year experience in the U.S. with the Titan and compares infection rates with the noncoated Alpha-1 IPP made by Mentor.

MATERIALS AND METHODS

Two thousand three hundred and fifty-seven Titan prostheses were implanted in the U.S. from September 2002 to August 2003, compared with the 482 noncoated Alpha-1 IPPs implanted over the same time period. Infection rates were compared, along with bacterial culture data. All data were collected from Mentor's internal database, as generated from the FDA's mandatory reporting of explanted medical devices, and available on the internet.

RESULTS

The infection rate for the coated Titan IPP was 1.06% (25/2,357). During the same time period, the infection rate for the Alpha-1 noncoated prosthesis was 2.07% (10/482). Staphylococcus species predominated in both groups (9/25 Titan, 6/10 Alpha-1).

CONCLUSIONS

At 1 year of follow-up, the data demonstrate that the hydrophilic coating on the Titan IPP confers a significant advantage in reducing the rate of infection over the noncoated device. Long-term follow-up on this first year database is needed before this innovation is accepted as the standard of care for prosthetic surgery. Nevertheless, the theoretical reduction in bacterial adhesion conferred by the hydrophilic PVP surface and the ability to choose which antibiotic the device is immersed in intraoperatively gives the implanting surgeon distinct advantages with this new product.

[The factors influencing metoprolol succinate release from hydroxypropyl methylcellulose matrix tablet]

The hydroxypropyl methylcellulose (HPMC) matrix tablet containing metoprolol succinate (MS) as a model drug was obtained by wet method compression tablet. The effects of the amount and viscosity of HPMC, the preparation method, compressing pressure, the amount of ethycellulose (EC), the pH of dissolution medium and the speed of basket rotation on the drug release from the matrix tablets were evaluated. The results showed that the release rate of metoprolol succinate from HPMC matrix tablets followed Higuchi equation. The release mechanism was in line with the synthetical effect of diffusion and corrosion. Drug release was influenced by the amount and viscosity of HPMC, the amount of EC in matrices, the preparation method and compressing pressure, etc. Drug release was not influenced by the pH of dissolution medium used, and not by the speed of basket rotation, either.

Development of a single unit extended release formulation for ZK 811 752, a weakly basic drug

ZK 811 752, a potent candidate for the treatment of autoimmune diseases, demonstrated pH-dependent solubility. The resulting release from conventional matrix tablets decreased with increasing pH-values of the dissolution medium. The aim of this study was to overcome this problem and to achieve pH-independent drug release. Three different polymers were used as matrix formers, the partly water-soluble and poorly swellable mixture of polyvinylacetate/polyvinylpyrrolidone, the water-insoluble and almost unswellable ethylcellulose (EC) and the water-soluble and highly swellable hydroxypropyl methylcellulose (HPMC). To solve the problem of pH-dependent solubility different organic acids, such as fumaric, tartaric, adipic, glutaric and sorbic acid were added to the drug-polymer system. The addition of organic acids to all three matrix formers was found to maintain low pH-values within the tablets during release of ZK 811 752 in phosphate buffer pH 6.8. Thus, the micro-environmental conditions for the dissolution of the weakly basic drug were kept almost constant. An extended release matrix tablet for ZK 811 752 consisting of drug, polymer and organic acid providing the desired pH-independent drug release has been developed.

Intrinsic adhesion properties of poly(vinyl pyrrolidone) to pharmaceutical materials: humidity effect

Poly(vinyl pyrrolidone) (PVP) is widely used for bioengineering and pharmaceutical applications, and its adhesion characteristics are critical. When used as a binder in pharmaceutical granulation, it covers the resultant granules and governs their surface properties. The intrinsic adhesion forces of PVP toward common hydrophobic (magnesium stearate) and hydrophilic (lactose) pharmaceutical materials have been studied as a function of relative humidity (RH). The effect of RH on adhesion force was more significant for the PVP/hydrophilic material than the PVP/hydrophobic material. Adhesion was lowest between 20 and 40% RH, and it increased at RH above 40% and below 20%. This is likely to be due to the development of capillary and triboelectrification forces, respectively. In a nano-indentation experiment using a silicon tip at room temperature, the PVP surface underwent a glass transition at 70% RH. This result suggests that surface softening contributes to the increased PVP adhesion at RH above 70%. To adjust the adhesion properties of PVP, humidity control should be an essential part of research and development. Effect of humidity on the adhesion forces between PVP and lactose (LT) or magnesium stearate (MS).

Probing Beta Relaxation in Pharmaceutically Relevant Glasses by Using DSC

PURPOSE

This study was conducted to demonstrate the use of differential scanning calorimetry (DSC) in detecting and measuring beta-relaxation processes in amorphous pharmaceutical systems.

METHODS

DSC was employed to study amorphous samples of poly(vinylpyrrolidone) (PVP), indomethacin (IM), and ursodeoxycholic acid (UDA) that were annealed at temperatures (T(a)) around 0.8 of their glass transition temperatures (T(g)). Dynamic mechanical analysis (DMA) was used to measure beta-relaxation in PVP.

RESULTS

Reheating the annealed samples gives rise to annealing peaks that occur below T(g). The peaks cannot be generated when annealing below the low temperature limit of beta-relaxation. These limits are around 50 degrees C for PVP, -20 degrees C for IM, and 30 degrees C for UDA. The effective activation energy (E) of the sub-T(g) relaxation has been estimated for each T(a) and found to increase with T(a), reflecting increasing contribution of the alpha-process. Estimates of E for beta-relaxation have been obtained from the lowest T(a) data, and are as follows: 68 (PVP), 56 (IM), 67 (UDA) kJ mol(-1).

CONCLUSIONS

DSC can be used for detecting beta-relaxation processes and estimating its low temperature limit, i.e., the temperature below which amorphous drugs would remain stable. It can also provide comparative estimates of low temperature stability of amorphous drugs in terms of the activation energies of the beta-relaxation.

Effects of formulation and process variables on the release of a weakly basic drug from single unit extended release formulations

A new commercially available extended release matrix material, Kollidon SR, composed of polyvinylacetate (PVA) and polyvinylpyrrolidone (PVP), was evaluated with respect to its ability to modulate the in vitro release of the weakly basic drug ZK 811 752. The effect of different formulation and process parameters on the release kinetics of ZK 811 752 from PVA/PVP based matrix tablets was investigated as a function of the (i) nature of excipient added to the drug-polymer mixtures, (ii) method of manufacturing (direct compression versus wet granulation), and (iii) effect of a post-compression curing step. ZK 811 752 containing extended release matrix tablets were successfully prepared by using Kollidon SR. The drug release from the matrix tablets increased by the addition of excipients such as maize starch, lactose and calcium phosphate. Addition of the highly swellable maize starch and the water-soluble lactose accelerated the drug release in a more pronounced manner compared to the water-insoluble calcium phosphate. Compound release from matrix tablets prepared by wet granulation was faster compared to the drug release from tablets prepared by direct compression. Post compression curing did not influence the drug release rate from drug-lactose-Kollidon SR formulations. Stability studies demonstrated no degradation of the drug substance and reproducible drug release patterns for matrix tablets stored at 25 degrees C/60% RH and 30 degrees C/70% RH for up to 6 months.

Modeling of drug release from celecoxib-PVP-meglumine amorphous systems

An empirical assessment of drug release from amorphous systems of celecoxib (CEL), poly(vinyl pyrrolidone) (PVP), and meglumine (MEG) was performed and compared with that for its crystalline form. CEL-PVP (4:1 w/w) binary and CEL-PVP-MEG (7:2:1 w/w) ternary amorphous systems provided higher drug dissolution. Mathematical modeling of drug release data was found to best fit the Hixson-Crowell release model. The biphasic drug release during a 6-h duration exhibited higher release kinetics in the first phase due to the presence of drug in amorphous form. The release kinetics subdued in the latter phase due to ongoing devitrification process in amorphous systems. A comprehensive understanding of drug release from amorphous systems will accentuate the rationalized design of amorphous drug delivery systems.

Flow rate of some pharmaceutical diluents through die-orifices relevant to mini-tableting

The effects of cylindrical orifice length and diameter on the flow rate of three commonly used pharmaceutical direct compression diluents (lactose, dibasic calcium phosphate dihydrate and pregelatinised starch) were investigated, besides the powder particle characteristics (particle size, aspect ratio, roundness and convexity) and the packing properties (true, bulk and tapped density). Flow rate was determined for three different sieve fractions through a series of miniature tableting dies of different orifice diameter (0.4, 0.3 and 0.2 cm) and thickness (1.5, 1.0 and 0.5 cm). It was found that flow rate decreased with the increase of the orifice length for the small diameter (0.2 cm) but for the large diameter (0.4 cm) was increased with the orifice length (die thickness). Flow rate changes with the orifice length are attributed to the flow regime (transitional arch formation) and possible alterations in the position of the free flowing zone caused by pressure gradients arising from the flow of self-entrained air, both above the entrance in the die orifice and across it. Modelling by the conventional Jones-Pilpel non-linear equation and by two machine learning algorithms (lazy learning, LL, and feed-forward back-propagation, FBP) was applied and predictive performance of the fitted models was compared. It was found that both FBP and LL algorithms have significantly higher predictive performance than the Jones-Pilpel non-linear equation, because they account both dimensions of the cylindrical die opening (diameter and length). The automatic relevance determination for FBP revealed that orifice length is the third most influential variable after the orifice diameter and particle size, followed by the bulk density, the difference between bulk and tapped densities and the particle convexity.

Effect of a melt agglomeration process on agglomerates containing solid dispersions

The purpose was to produce solid dispersions of a poorly water-soluble drug, Lu-X, by melt agglomeration in a laboratory scale rotary processor. The effect of binder type and method of manufacturing on the dissolution profile of Lu-X was investigated. Lactose monohydrate and Lu-X were melt agglomerated with Rylo MG12, Gelucire 50/13, PEG 3000, or poloxamer 188. Either a mixture of binder, drug, and excipient was heated to a temperature above the melting point of the binder (melt-in procedure) or a dispersion of drug in molten binder was sprayed on the heated excipient (spray-on procedure). The agglomerates were characterized by DSC, XRPD, SEM, and EDX-SEM. The study showed that the agglomerates containing solid dispersions had improved dissolution rates compared to physical mixtures and pure drug. The melt-in procedure gave a higher dissolution rate than the spray-on procedure with PEG 3000, poloxamer 188, and Gelucire 50/13, whereas the opposite was found with Rylo MG12. This was explained by differences in mechanisms of agglomerate formation and growth, which were dominated by immersion with PEG 3000, poloxamer 188, and Gelucire 50/13, and by distribution and coalescence with Rylo MG12. The spray-on procedure resulted in a higher content of Lu-X in the core of the agglomerates when immersion was the dominating mechanism, and in a higher content in the agglomerate surface when distribution was dominating. The melt-in procedure resulted generally in a homogeneous distribution of Lu-X in the agglomerates. The compounds in the agglomerates were found primarily to be crystalline, and the dissolution profiles were unchanged after 12 weeks storage at 25 degrees C at 50% RH.

[Substantiation of the composition, technology and standardization of the original medicinal forms of interferon and bactisporin]

New medicinal forms of immunobiological preparations--human lekocytic interferon and bactisporin--have been developed for local application in dentistry, surgery, gynecology. As the basis for these preparations, the pharmacopeial collagen solution has been used. The results obtained in this investigation indicate that the preparations are safe and possess wound-healing properties.

Tablets with high lactose content: effects of some binders and disintegrants on their properties

Tablets containing 91% lactose monohydrate and 4% starch pregelatinized exhibited the best technical properties in comparison to tablets of similar composition with either povidone plus croscarmellose sodium or hydroxypropylcellulose low substituted as binders/disintegrants.

Solid films of blended poly(vinyl alcohol)/poly(vinyl pyrrolidone) for topical S-nitrosoglutathione and nitric oxide release

Nitric oxide (NO) is responsible for biological actions in mammals, ranging from the control of arterial pressure to immunological responses. In this study, S-nitrosoglutathione (GSNO), a spontaneous NO donor, was incorporated in solid films of blended poly(vinyl alcohol) (PVA) and poly(vinyl pyrrolidone) (PVP) comprising a biomaterial with potential for the local delivery of NO. In dry conditions, the extinction of the absorption bands of GSNO was correlated with the increase of the absorption band of its dimmer, GS-SG, implying NO release through the homolytic cleavage of the S-N bond. Mass spectrometry was used to confirm and to monitor the release of free NO from solid PVA/PVP-GSNO films to the gas phase. Kinetic measurement based on the Griess reaction was used to show that solid PVA/PVP-GSNO films are also capable of releasing both NO and GSNO to aqueous solution trough diffusion. Storage experiments have shown that GSNO is highly stabilized in the dry PVA/PVP matrix. The results indicate that GSNO-containing PVA/PVP films may be used for delivering free NO and/or GSNO topically and controllably.

Distribution and Effect of Water Content on Molecular Mobility in Poly(vinylpyrrolidone) Glasses: A Molecular Dynamics Simulation

PURPOSE

This work explores the distribution of water and its effects on molecular mobilities in poly(vinylpyrrolidone) (PVP) glasses using molecular dynamics (MD) simulation technology.

METHODS

PVP glasses containing 0.5% and 10% w/w water and a small amount of ammonia and Phe-Asn-Gly were generated. Physical aging processes and associated structural and dynamic properties were monitored vs. time for periods up to 0.1 micros by MD simulation.

RESULTS

Increasing water content from 0.5% to 10% w/w was found to reduce the Tg by about 90 K and increase the rates of volume and enthalpy relaxation. At 0.5% w/w, water molecules are mostly isolated and uniformly distributed while at 10% w/w, water distribution is markedly heterogeneous, with strands of water molecules occupying channels between the polymer chains. At 10% w/w, each water molecule has an average of 2.0 neighboring water molecules. The plasticization effects of water were revealed in diffusion coefficient increases of 3.7-, 7.3-, and 7.6-fold for water, ammonia, and the individual polyvinylpyrrolidone segments, respectively, and in shorter relaxation times (37- to 47-fold) for rotation of polymer segments with an elevation in water content from 0.5% to 10% w/w. Water diffusivity was found to linearly correlate with the number of neighboring water molecules. Rotation of the PVP segments is comprised of a fast wobble motion within a highly restrained cavity and a slow rotation over a wider angular space. Only the slow rotation was shown to be significantly affected by water content.

CONCLUSIONS

Water distribution in the PVP glass is highly heterogeneous at 10% w/w water, reflecting the formation of water strands or small clusters rather than complete phase separation. Local enhancement of mobility with increasing water content has been demonstrated using MD simulations.

Physical stability of the amorphous state of loperamide and two fragment molecules in solid dispersions with the polymers PVP-K30 and PVP-VA64

The purpose of the present study was to investigate the impact of intermolecular forces on the stability of the amorphous state of loperamide and two of its fragment molecules (4-dimethylamino-N,N-dimethyl-2,2-diphenyl-butyramide (F1) and 4-(4-chlorophenyl)-4-piperidinol (F2)) in solid dispersions with PVP-K30 and PVP-VA64. The stability of originally homogeneous and amorphous dispersions was investigated under different storage conditions. The chemical stability of the compounds was evaluated with HPLC. TGA-analysis was used in order to assess the amount of water in the samples, whereas MT-DSC-measurements were performed to investigate changes in the physical state of the compounds caused by the storage procedure. TGA-analysis reveals a higher uptake of water in humid conditions of the dispersions with PVP-K30 in comparison to those with PVP-VA64, hereby reflecting the more hydrophilic nature of the former polymer. This water acts as a plasticizing agent resulting in an increased mobility and decreased glass transition temperature. Since the degree of supersaturation and the molecular mobility have an influence on the stability of the amourphous state, both parameters were assessed. With respect to the degree of supersaturation of the compounds in the dispersions, the materials seem to be very much alike. Therefore it was postulated that the induction of crystallization in the F1/polymer dispersions stored at high RH (52%) is due to higher molecular mobility of this compound in the dispersions in comparison to F2. The hydrogen bonds that are being formed between F2 and the polymers reduce its mobility and secure this compound from crystallization upon storage, thus indicating the importance of specific interactions with respect to stability issues of solid dispersions. No hydrogen bonds are formed between F1 and the polymers. As a result, the stability of the amorphous state of the compound is being compromised and crystallization takes place. Loperamide, that also does not form hydrogen bonds with the polymers, is less susceptible to crystallization due to its intrinsic good glass forming properties.

Strong dc electric field applied to supersaturated aqueous glycine solution induces nucleation of the gamma polymorph

Applying a strong static electric field to supersaturated aqueous glycine solutions resulted in the nucleation of the gamma polymorph. This is the first report of a strong dc field inducing the nucleation of a neutral solute in a supersaturated solution. We attribute this effect to the electric-field-induced orientation of the highly polar glycine molecules in large preexisting solute clusters, helping them organize into a crystalline structure. This result also lends further support to our proposed optical-Kerr mechanism for nonphotochemical laser-induced nucleation.

[Pharmaceutical hydrophilic gels]

From the pharmacopoeial standpoint, gels, together with ointments, creams, pastes, cataplasmata, and medicated plasters, rank among the group of topical semisolid preparations applied to the skin. They are bicoherent systems composed of the internal phase made of a polymer producing a coherent three-dimensional net-like structure, which fixes the liquid vehicle as the external phase. Intermolecular forces bind the molecules of the solvent to a polymeric net, thus decreasing the mobility of these molecules and producing a structured system with increased viscosity. The physical and chemical bonds binding the particles of the internal phase provide a relatively stable structure, which can originate by swelling of solid polymers, or by decreasing the solubility of the polymer in a solution. An important group of gels used in pharmacy are hydrophylic gels, or hydrogels, usually made of hydrophyilc polymers, which under certain conditions and polymer concentration, jellify. Attention of pharmaceutical research now concentrates primarily on hydrophilic gels, as this dosage form seems to be prospective for the development of modern drugs based on systems with prolonged and controlled release of active ingredients.