Patterns of dosage regimen instructions regarding topical medicines: how is the information perceived by patients?

BACKGROUND: The communication of dosage regimen instructions by physicians is of utmost importance on treatment adherence. Few studies until now have approached the topical treatment adherence subject. OBJECTIVE: This study aims the characterization of dosage regimen instructions given by physicians and the assessment of chronic dermatological patients' perception regarding these instructions. METHODS: Two instruments one for physicians (PHYSDOSAGE) and one for patients (PATIENTDOSAGE) were developed and applied in a cross-sectional, descriptive and exploratory study to two independent samples composed by 91 physicians and 43 patients. RESULTS: Most of physicians reported to provide dosage regimen instructions. When cross checking information from both studied samples, physicians and patients, it was concluded that physicians reported to provide more frequently oral and written treatment instructions, e.g. electronic prescription, than patients reported having received it. Also, physicians claimed to often provide information about the duration of treatment and the frequency of topical medicines' application, which was not acknowledged by patients. CONCLUSIONS: Contradictory results were found between the physicians' information input and the patients' perception about dosage regimen instructions provided during the consultation. These findings could negatively influence the treatment adherence and the clinical outcomes. Thus, it is of paramount importance the implementation of strategies to improve optimal communication of dosage regimen instructions for topical medicines.

Knowledge and Practices of Community Pharmacists in Topical Dermatological Treatments.

The connection between pharmacists' knowledge and practice on the provided information to patients about dermatoses and their treatment is insufficiently characterized. Furthermore, pharmacists' contributions in counselling and in promoting adherence to topical treatment is not fully understood. This study has three main objectives. It aims to identify the knowledge and practices of pharmacists about dermatoses and their treatment, and to compare the perspective of pharmacists with that of patients regarding treatment information, with the future goal of establishing guidelines on the communication of dosage regimen instructions to dermatological patients and promotion of adherence to treatment, filling a gap. A cross-sectional, exploratory, and descriptive study was carried out. Based on experts' prior knowledge and extensive collected literature information, two questionnaire protocols, one for pharmacists and another one for patients, were designed. Exploratory factor analysis (EFA) and confirmatory factor analysis (CFA) were carried out in relation to the pharmacists' questionnaire for instrument validation. The results indicate that knowledge of pharmacists regarding dermatoses and their treatment is considered acceptable. Most of the pharmacists were reported to provide information to patients. Oppositely, patients reported not to have receive it. This is an important issue because pharmacists play a primary role in the management of several diseases. As non-adherence can be triggered by poor understanding of the dosing instructions, pharmacists' communication practices play an important role in improving this hinderance. Results from this study identified pharmacist-patient communication gaps, so the development of guidelines to improve the transmission of clear dosage regimen instructions and knowledge about patient's disease are of paramount importance. Training programs for continuous education of pharmacist should be implemented to solve the identified communication problems found in this study.

Characterization of an antioxidant surfactant-free topical formulation containing Castanea sativa leaf extract.

CONTEXT: Inclusion of antioxidants in topical formulations can contribute to minimize oxidative stress in the skin, which has been associated with photoaging, several dermatosis and cancer. OBJECTIVE: A Castanea sativa leaf extract with established antioxidant activity was incorporated into a semisolid surfactant-free formulation. The objective of this study was to perform a comprehensive characterization of this formulation. MATERIALS AND METHODS: Physical, microbiological and functional stability were evaluated during 6 months storage at 20 °C and 40 °C. Microstructure elucidation (cryo-SEM), in vitro release and in vivo moisturizing effect (Corneometer® CM 825) were also assessed. RESULTS AND DISCUSSION: Minor changes were observed in the textural and rheological properties of the formulation when stored at 20 °C for 6 months and the antioxidant activity of the plant extract remained constant throughout the storage period. Microbiological quality was confirmed at the end of the study. Under accelerated conditions, higher modifications of the evaluated parameters were observed. Cryo-SEM analysis revealed the presence of oil droplets dispersed into a gelified external phase. The release rate of the antioxidant compounds (610 ± 70 µgh(-0.5)) followed Higuchi model. A significant in vivo moisturizing effect was demonstrated, that lasted at least 4 h after product's application. CONCLUSION: The physical, functional and microbiological stability of the antioxidant formulation was established. Specific storage conditions should be recommended considering the influence of temperature on the stability. A skin hydration effect and good skin tolerance were also found which suggests that this preparation can be useful in the prevention or treatment of oxidative stress-mediated dysfunctions.

Biodistribution and pharmacokinetics of dapivirine-loaded nanoparticles after vaginal delivery in mice.

PURPOSE: To assess the potential of polymeric nanoparticles (NPs) to affect the genital distribution and local and systemic pharmacokinetics (PK) of the anti-HIV microbicide drug candidate dapivirine after vaginal delivery. METHODS: Dapivirine-loaded, poly(ethylene oxide)-coated poly(epsilon-caprolactone) (PEO-PCL) NPs were prepared by a nanoprecipitation method. Genital distribution of NPs and their ability to modify the PK of dapivirine up to 24 h was assessed after vaginal instillation in a female mouse model. Also, the safety of NPs upon daily administration for 14 days was assessed by histological analysis and chemokine/cytokine content in vaginal lavages. RESULTS: PEO-PCL NPs (180-200 nm) were rapidly eliminated after administration but able to distribute throughout the vagina and lower uterus, and capable of tackling mucus and penetrate the epithelial lining. Nanocarriers modified the PK of dapivirine, with higher drug levels being recovered from vaginal lavages and vaginal/lower uterine tissues as compared to a drug suspension. Systemic drug exposure was reduced when NPs were used. Also, NPs were shown safe upon administration for 14 days. CONCLUSIONS: Dapivirine-loaded PEO-PCL NPs were able to provide likely favorable genital drug levels, thus attesting the potential value of using this vaginal drug delivery nanosystem in the context of HIV prophylaxis.

Assessing the physical-chemical properties and stability of dapivirine-loaded polymeric nanoparticles.

Nanocarriers may provide interesting delivery platforms for microbicide drugs and their characterization should be addressed early in development. Differently surface-engineered dapivirine-loaded, poly(epsilon-caprolactone) (PCL)-based nanoparticles (NPs) were obtained by nanoprecipitation using polyethylene oxide (PEO), sodium lauryl sulfate (SLS), or cetyltrimethylammonium bromide (CTAB) as surface modifiers. Physical-chemical properties of NP aqueous dispersions were evaluated upon storage at -20-40 °C for one year. NPs presented 170-200 nm in diameter, roundish-shape, low polydispersity index (≤0.18), and high drug association efficiency (≥97%) and loading (≥12.7%). NPs differed in zeta potential, depending on surface modifier (PEO: -27.9 mV; SLS: -54.7 mV; CTAB: +42.4 mV). No interactions among formulation components were detected by differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy (FTIR), except for SLS-PCL NPs. Colloidal properties of NPs were lost at -20 °C storage. Negatively charged NPs were stable up to one year at 5-40°C; as for CTAB-PCL NPs, particle aggregation was observed from 30 to 90 days of storage depending on temperature. Colloidal instability affected the in vitro drug release of CTAB-PCL NPs after 360 days. In any case, no degradation of dapivirine was apparent. Overall, PEO-PCL and SLS-PCL NPs presented suitable properties as nanocarriers for dapivirine. Conversely, CTAB-PCL NPs require additional strategies in order to increase stability.

In vitro and ex vivo evaluation of polymeric nanoparticles for vaginal and rectal delivery of the anti-HIV drug dapivirine.

Prevention strategies such as the development of microbicides are thought to be valuable in the fight against HIV/AIDS. Despite recent achievements, there is still a long road ahead in the field, particularly at the level of drug formulation. Drug nanocarriers based on polymers may be useful in enhancing local drug delivery while limiting systemic exposure. We prepared differently surface-engineered poly(ε-caprolactone) (PCL) nanoparticles (NPs) and tested their ability to modulate the permeability and retention of dapivirine in cell monolayers and pig vaginal and rectal mucosa. NPs coated with poly(ethylene oxide) (PEO) were shown able to reduce permeability across monolayers/tissues, while modification of nanosystems with cetyl trimethylammonium bromide (CTAB) enhanced transport. In the case of coating NPs with sodium lauryl sulfate (SLS), dapivirine permeability was unchanged. All NPs increased monolayer/tissue drug retention as compared to unformulated dapivirine. This fact was associated, at least partially, to the ability of NPs to be taken up by cells or penetrate mucosal tissue. Cell and tissue toxicity was also affected differently by NPs: PEO modification decreased the in vitro (but not ex vivo) toxicity of dapivirine, while higher toxicity was generally observed for NPs coated with SLS or CTAB. Overall, presented results support that PCL nanoparticles are capable of modulating drug permeability and retention in cell monolayers and mucosal tissues relevant for vaginal and rectal delivery of microbicides. In particular, PEO-modified dapivirine-loaded PCL NPs may be advantageous in increasing drug residence at epithelial cell lines/mucosal tissues, which may potentially increase the efficacy of microbicide drugs.

Development and validation of a HPLC method for the assay of dapivirine in cell-based and tissue permeability experiments.

Dapivirine, a non-nucleoside reverse transcriptase inhibitor, is being currently used for the development of potential anti-HIV microbicide formulations and delivery systems. A new high-performance liquid chromatography (HPLC) method with UV detection was developed for the assay of this drug in different biological matrices, namely cell lysates, receptor media from permeability experiments and homogenates of mucosal tissues. The method used a reversed-phase C18 column with a mobile phase composed of trifluoroacetic acid solution (0.1%, v/v) and acetonitrile in a gradient mode. Injection volume was 50µL and the flow rate 1mL/min. The total run time was 12min and UV detection was performed at 290nm for dapivirine and the internal standard (IS) diphenylamine. A Box-Behnken experimental design was used to study different experimental variables of the method, namely the ratio of the mobile phase components and the gradient time, and their influence in responses such as the retention factor, tailing factor, and theoretical plates for dapivirine and the IS, as well as the peak resolution between both compounds. The optimized method was further validated and its usefulness assessed for in vitro and ex vivo experiments using dapivirine or dapivirine-loaded nanoparticles. The method showed to be selective, linear, accurate and precise in the range of 0.02-1.5µg/mL. Other chromatographic parameters, namely carry-over, lower limit of quantification (0.02µg/mL), limit of detection (0.006µg/mL), recovery (equal or higher than 90.7%), and sample stability at different storage conditions, were also determined and found adequate for the intended purposes. The method was successfully used for cell uptake assays and permeability studies across cell monolayers and pig genital mucosal tissues. Overall, the proposed method provides a simple, versatile and reliable way for studying the behavior of dapivirine in different biological matrices and assessing its potential as an anti-HIV microbicide drug.

Interactions of microbicide nanoparticles with a simulated vaginal fluid.

The interaction with cervicovaginal mucus presents the potential to impact the performance of drug nanocarriers. These systems must migrate through this biological fluid in order to deliver their drug payload to the underlying mucosal surface. We studied the ability of dapivirine-loaded polycaprolactone (PCL)-based nanoparticles (NPs) to interact with a simulated vaginal fluid (SVF) incorporating mucin. Different surface modifiers were used to produce NPs with either negative (poloxamer 338 NF and sodium lauryl sulfate) or positive (cetyltrimethylammonium bromide) surface charge. Studies were performed using the mucin particle method, rheological measurements, and real-time multiple particle tracking. Results showed that SVF presented rheological properties similar to those of human cervicovaginal mucus. Analysis of NP transport indicated mild interactions with mucin and low adhesive potential. In general, negatively charged NPs underwent subdiffusive transport in SVF, i.e., hindered as compared to their diffusion in water, but faster than for positively charged NPs. These differences were increased when the pH of SVF was changed from 4.2 to 7.0. Diffusivity was 50- and 172-fold lower in SVF at pH 4.2 than in water for negatively charged and positively charged NPs, respectively. At pH 7.0, this decrease was around 20- and 385-fold, respectively. The estimated times required to cross a layer of SVF were equal to or lower than 1.7 h for negatively charged NPs, while for positively charged NPs these values were equal to or higher than 7 h. Overall, our results suggest that negatively charged PCL NPs may be suitable to be used as carriers in order to deliver dapivirine and potentially other antiretroviral drugs to the cervicovaginal mucosal lining. Also, they further reinforce the importance in characterizing the interactions of nanosystems with mucus fluids or surrogates when considering mucosal drug delivery.

Preparation of polyelectrolyte nanocomplexes containing recombinant human hepatocyte growth factor as potential oral carriers for liver regeneration.

The large number of cytokines and growth factors implicated in the regulation of liver regeneration has led to the possibility of using these molecules in therapy, namely, in the case of recombinant human hepatocyte growth factor (rhHGF). The importance and potential clinical usefulness of rhHGF has been extensively studied and documented, with results suggesting that this molecule could be a powerful tool toward increased success in hepatic regenerative therapy. However, the peptidic nature of this drug presents several challenges toward its effective administration and targeting. The possibility of encapsulating rhHGF in dextran sulfate/chitosan nanoparticles to allow its oral administration and direct liver-targeting is discussed in this manuscript. Details of a rapid and simple method for the preparation of such rhHGF-loaded nanocomplexes are presented. Beyond the practical aspects of the method, characterization techniques and main experimental features of obtained nanocarriers are also briefly analyzed and discussed.

Polymeric nanoparticles affect the intracellular delivery, antiretroviral activity and cytotoxicity of the microbicide drug candidate dapivirine.

PURPOSE: To assess the intracellular delivery, antiretroviral activity and cytotoxicity of poly(ε-caprolactone) (PCL) nanoparticles containing the antiretroviral drug dapivirine. METHODS: Dapivirine-loaded nanoparticles with different surface properties were produced using three surface modifiers: poloxamer 338 NF (PEO), sodium lauryl sulfate (SLS) and cetyl trimethylammonium bromide (CTAB). The ability of nanoparticles to promote intracellular drug delivery was assessed in different cell types relevant for vaginal HIV transmission/microbicide development. Also, antiretroviral activity of nanoparticles was determined in different cell models, as well as their cytotoxicity. RESULTS: Dapivirine-loaded nanoparticles were readily taken up by different cells, with particular kinetics depending on the cell type and nanoparticles, resulting in enhanced intracellular drug delivery in phagocytic cells. Different nanoparticles showed similar or improved antiviral activity compared to free drug. There was a correlation between increased antiviral activity and increased intracellular drug delivery, particularly when cell models were submitted to a single initial short-course treatment. PEO-PCL and SLS-PCL nanoparticles consistently showed higher selectivity index values than free drug, contrasting with high cytotoxicity of CTAB-PCL. CONCLUSIONS: These results provide evidence on the potential of PCL nanoparticles to affect in vitro toxicity and activity of dapivirine, depending on surface engineering. Thus, this formulation approach may be a promising strategy for the development of next generation microbicides.

Mucoadhesive nanomedicines: characterization and modulation of mucoadhesion at the nanoscale.

INTRODUCTION: The benefits of mucoadhesive systems are related to the increased in situ residence and intimate contact of the delivery vehicle with the mucosa. The recent emergence of nanomedicine and the properties of nanoparticulate systems have created new challenges in understanding the nature and mechanisms of nanoscale mucoadhesion and in the development of methodologies for measuring its mucoadhesive potential. Even when usually regarded as an advantageous property, mucoadhesion can be an inconvenience for nanosystems, and strategies have been developed for minimizing interactions with the mucosal tissues/fluids. AREAS COVERED: This article summarizes the basic concepts of mucoadhesion at the nanoscale, different techniques used for measuring the mucoadhesive potential of nanosystems and strategies for increasing/decreasing mucoadhesive interactions. EXPERT OPINION: The mucoadhesion behavior of materials in bulk and at the nanoscale can significantly differ. Advances in the methodology used for studying the mucoadhesion phenomenon have contributed to its better understanding and, more importantly, the development of strategies to increase/decrease mucoadhesion. However, development of new methodologies for studying mucoadhesion at the nanoscale and the refinement of existing methodologies are still required. Also, a substantial amount of information is still lacking, particularly related to formulation issues, on how to translate lessons learnt at the bench top to the bed side.

Development and validation of a rapid reversed-phase HPLC method for the determination of the non-nucleoside reverse transcriptase inhibitor dapivirine from polymeric nanoparticles.

The objective of this work was to develop and validate a rapid reversed-phase (RP) high-performance liquid chromatography (HPLC) method for the in vitro pharmaceutical characterization of dapivirine-loaded polymeric nanoparticles. Chromatographic runs were performed on a RP C18 column with a mobile phase comprising acetonitrile-0.5% (w/v) triethanolamine solution in isocratic mode (80:20, v/v) at a flow rate of 1 ml/min. Dapivirine was detected at a wavelength of 290 nm. The method was shown to be specific, linear in the range of 1-50 microg/ml (R(2)=0.9998), precise at the intra-day and inter-day levels as reflected by the relative standard deviation values (less than 0.85%), accurate (recovery rate of 100.17+/-0.35%), and robust to changes in the mobile phase and column brand. The detection and quantitation limits were 0.08 and 0.24 microg/ml, respectively. The method was successfully used to determine the loading capacity and association efficiency of dapivirine in poly(lactic-co-glycolic acid)-based nanoparticles and its in vitro release.

Nanotechnology-based systems for the treatment and prevention of HIV/AIDS.

The HIV/AIDS pandemic is an increasing global burden with devastating health-related and socioeconomic effects. The widespread use of antiretroviral therapy has dramatically improved life quality and expectancy of infected individuals, but limitations of currently available drug regimens and dosage forms, alongside with the extraordinary adapting capacity of the virus, have impaired further success. Alongside, circumventing the escalating number of new infections can only be attained with effective and practical preventative strategies. Recent advances in the field of drug delivery are providing evidence that engineered nanosystems may contribute importantly for the enhancement of current antiretroviral therapy. Additionally, groundwork is also being carried out in the field nanotechnology-based systems for developing preventative solutions for HIV transmission. This manuscript reviews recent advances in the field of nanotechnology-based systems for the treatment and prevention of HIV/AIDS. Particular attention is given to antiretroviral drug targeting to HIV reservoirs and the usefulness of nanosystems for developing topical microbicides and vaccines.

In vitro protective effect of Hypericum androsaemum extract against oxygen and nitrogen reactive species.

Hypericum androsaemum L. (Gutiferae) is a medicinal plant growing in Western Europe that has been used in traditional medicine in the prevention or treatment of liver diseases. Oxidative stress and nitrosative stress are common pathogenetic mechanisms contributing to initiation and progression of hepatic damage in several liver disorders. In the present study, an ethanol:water (4:6) extract from H. androsaemum branches and leaves were evaluated for its putative in vitro scavenging effects on 1,1-diphenyl-2-picrylhydrazil radical, on reactive oxygen species, namely HO•, O2•-, ROO•, ¹O2 and H2O2 and on reactive nitrogen species, namely •NO and ONOO⁻. The hypericum extract presented a remarkable capacity to scavenge all the tested reactive species, all the IC50 values being found at the µg/ml level. IC50 values for 1,1-diphenyl-2-picrylhydrazil, and for the reactive oxygen species O2•-, H2O2, HO• and ¹O2 were 11.3 ± 0.7, 32.7 ± 3.4, 944 ± 47, 595 ± 82, 28.3 ± 1.2 µg/ml respectively. The oxygen radical absorbance capacity value obtained for ROO• was 1.5 ± 0.1 µmol Trolox equivalents/mg extract. The IC50 values for •NO and ONOO⁻ were 2.2 ± 0.2 and 1.2 ± 0.1 µg/ml respectively. The content of total phenolics was 281 ± 2 mg of gallic acid equivalents/g of lyophilized extract. The observed antioxidant activity provides scientific support for the reported therapeutic use of H. androsaemum, though further in vitro and in vivo studies are required to ascertain the risk/benefit score at therapeutic concentrations.

Rheological properties of vaginal hydrophilic polymer gels.

The objective of this work was to investigate the main theological features of vaginal hydrophilic polymer gels and to elucidate about the relationship between these characteristics and gels composition, and their general influence in therapeutic/usage purpose. Flow and dynamic oscillatory properties of four commercially available (Conceptrol, Gynol II, RepHresh, and Replens) and two investigational vaginal gels were determined by cone-and-plate rheometry, at body temperature. Several parameters (apparent viscosity, complex viscosity, storage modulus, loss modulus, critical oscillatory stress, tan delta, thixotropy and yield stress) were measured and/or calculated. Gels presented non-Newtonian, pseudoplastic, thixotropic behavior, with yield stress. Overall viscosities varied between 13500 Pa.s and approximately 80 Pa.s within a biologically relevant shear rate interval (0.01-100 s(-1)). Yield stress values were variable between different determination methods but coherent in terms of ranking. Also, tested gels showed viscoelastic properties, being characterized by predominant elastic solid-like behavior. Rheological behavior of vaginal gels strongly depended on the type of gelling agent used, which potentially influences their spreading and retention properties when administered in the vaginal canal. Small variations in gels composition can result in substantial changes in their features, namely viscosity, yield stress and thixotropy. Rheological properties of tested gels appeared to be correlated with their therapeutic/usage purpose.

Performance of an in vitro mucoadhesion testing method for vaginal semisolids: influence of different testing conditions and instrumental parameters.

The purpose of this work was to develop an in vitro mucoadhesion testing method for vaginal semisolid formulations. The proposed method was based on the measurement of the force (detachment force, Fdt) and the work (work of adhesion, Wad) needed to detach a sample of cow vaginal mucosa from a semisolid formulation, using a commercially available texture analyzer. Several testing conditions and instrumental parameters were tested in order to evaluate the mucoadhesive potential of a model vaginal semisolid formulation (1% Carbopol 974P gel). Also, mucoadhesive potential of several commercially available vaginal semisolid products was evaluated. Obtained results showed that the method is reproducible even when the same cow mucosa sample is used up to six times. The similarity of the fluid used to bathe the vaginal mucosa to the one naturally occurring in the vagina influenced considerably the performance of the test, advising that simulation of vaginal fluid properties is important when measuring mucoadhesive properties. Also, temperature of experiment was an important fact to be considered, as results showed slight but significant differences between body (37 degrees C) and room (20 degrees C) temperature. Fdt and Wad increased with increasing instrumental parameters while a plateau region was observable at higher values of probe speed, probe force, and mucosa/sample contact time. Comparison between results for Fdt and Wad demonstrated that although both parameters are generally in agreement, Wad seems to be more reliable and reproducible when evaluating mucoadhesion. Evaluation of commercially available formulations confirmed that experimental conditions are important features that can influence significantly the determination of mucoadhesive potential, being the proposed method an interesting and useful tool in the in vitro evaluation of vaginal semisolids.

Influencia de las condiciones de almacenaje en la plasticidad y la liberación de Fentiazac a partir de una formulación tópica / Influence of the storage conditions on the plasticity and release of Fentiazac incorporated in a topic formulation

En el presente trabajo se ha estudiado la influencia del aumento de la plasticidad en la liberación de un anti-inflamatorio no esteroideo (Fentiazac) vehiculado en gel, en función del tiempo y temperatura de almacenaje. A través de ensayos reológicos y de liberación in vitro utilizando membranas epidérmicas artificiales (SARTORIUS), se concluye que estos dos parámetros (tiempo y temperatura de almacenaje) influyen en el comportamiento reológico del producto y, consecuentemente, en la liberación del anti-inflamatorio (AU)