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The decorporation kinetics of internal radionuclide contamination is a long-term treatment raising modeling, planning, and managing problems, especially in the case of late intervention when the radiotoxic penetrated the deep compartments. The decorporation effectiveness of the highly radiotoxic 65ZnCl2 by Zn-DTPA (dosed at 3.32 mg and 5 mg/0.25 mL/100 g body weight) was investigated in Wistar male rats over a ten-day period under various treatments (i.e., as a single dose before contamination; as a single dose before and 24 h after contamination; and as daily administrations for five consecutive days starting on day 12 after contamination). The radioactivity was measured using the whole-body counting method. Mono- and bi-compartmental decorporation kinetics models proved applicable in the case of a rapid intervention. It was found that a diffusion model of the radionuclide from tissues to blood better describes the decorporation kinetics after more than ten days post treatment, and the process has been mathematically modeled as a diffusion from an infinite reservoir to a semi-finite medium. The mathematical solution led to a square-root law for describing the 65Zn decorporation. This law predicts a slower release than exponential or multiexponential equations, and could better explain the very long persistence of radionuclides in the living body. Splitting data and modeling in two steps allows a better understanding, description and prediction of the evolution of contamination, a separate approach to the treatment schemes of acute and chronic contamination.
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The in vivo release and absorption of drugs are dependent on the interplay between many factors related to compound, formulation, and physiological properties. The mathematical models of oral drug absorption attempt to strike a balance between a complete description that takes into consideration as many independent factors as possible, and simple models that operate with fewer parameters, based mainly on critical factors. The latter models are by far more robust and easier to apply to predict the extent and sometimes even the rate of absorption. The present paper attempted to develop a simple model to describe the time course of absorption of the hydrophilic drug captopril (CPT) at the early phases of absorption, with implications mainly in the induction and early stages of achieving its therapeutic effect. As a phenomenological model, the instantaneous release of CPT was considered in the gastrointestinal fluid, leading to a constant drug concentration for a prolonged time, followed by a 'long path diffusion' inside the intestinal wall and a very low concentration at the interface intestinal wall-blood. These conditions regarding CPT concentration were translated into initial and boundary mathematical conditions for the diffusion equation in the intestinal wall. The solution of the diffusion equation led in the end to a square root law describing the dependence between the fraction of the drug absorbed and time. The model was successfully applied to data obtained in five bioequivalence studies: three comparing plasma levels achieved after the administration of a single dose of CPT 50 mg, one evaluating CPT pharmacokinetics after a 100 mg dose, and a fifth comparing CPT pharmacokinetics of two fixed-dose combinations of CPT 50 mg and hydrochlorothiazide 25 mg.
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Captopril/farmacocinética , Absorção Intestinal/fisiologia , Modelos Biológicos , Administração Oral , Área Sob a Curva , Estudos Cross-Over , Relação Dose-Resposta a Droga , Liberação Controlada de Fármacos , HumanosRESUMO
Due to its low solubility, carbamazepine (CBZ) exhibits slow and incomplete release in the gastrointestinal tract and, hence, variable pharmacokinetics and pharmacodynamic effect. Lots of methods have been devised to improve its solubility, the large number of proposed solutions being a sign that the problem is not yet satisfactorily solved. The persistent problem is that predictable release kinetics, an increased rate but within defined limits, are required to avoid high absorption variability. This paper presents a synthesis of a carbamazepine-ß-cyclodextrin inclusion complex (CBZ-ß-CD), the characterization of the physical mixture, CBZ, ß-CD and the CBZ-ß-CD inclusion complex using Fourier transform infrared spectroscopy, scanning electron microscopy, simultaneous thermal analysis and X-ray diffraction, formulation of chewable tablets, determination of the dissolution of carbamazepine in medium containing 1% sodium lauryl sulfate (LSS), and in simulated saliva (SS), mathematical modeling of release kinetics. The kinetics of total CBZ release from tablets containing CBZ-ß-CD and super-disintegrant F-Melt in both SS and LSS followed two steps: a burst release in the first minutes and a slower release in intervals up to 60 min. The release in the second phase has been well described by the Higuchi and Peppas models, which advocate a controlled release by combined diffusion and with some phenomena of swelling and relaxation of the matrix generated by the crospovidone component of the F-Melt excipient.
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Doxorubicin hydrochloride (DOX) is currently used to treat orthotropic and metastatic breast cancer. Because of its side effects, the use of DOX in cancer patients is sometimes limited; for this reason, several scientists tried designing drug delivery systems which can improve drug therapeutic efficacy and decrease its side effects. In this study, we designed, prepared, and physiochemically characterized nonionic surfactant vesicles (NSVs) which are obtained by self-assembling different combinations of hydrophilic (Tween 20) and hydrophobic (Span 20) surfactants, with cholesterol. DOX was loaded in NSVs using a passive and pH gradient remote loading procedure, which increased drug loading from â¼1 to â¼45%. NSVs were analyzed in terms of size, shape, size distribution, zeta potential, long-term stability, entrapment efficiency, and release kinetics, and nanocarriers having the best physiochemical parameters were selected for further in vitro tests. NSVs with and without DOX were stable and showed a sustained drug release up to 72 h. In vitro studies, with MCF-7 and MDA MB 468 cells, demonstrated that NSVs, containing Span 20, were better internalized in MCF-7 and MDA MB 468 cells than NSVs with Tween 20. NSVs increased the anticancer effect of DOX in MCF-7 and MDA MB 468 cells, and this effect is time and dose dependent. In vitro studies using metastatic and nonmetastatic breast cancer cells also demonstrated that NSVs, containing Span 20, had higher cytotoxicity than NSVs with Tween 20. The resulting data suggested that DOX-loaded NSVs could be a promising nanocarrier for the potential treatment of metastatic breast cancer.
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OBJECTIVE: This paper analyzes the potential outliers in the bioanalytical and clinical part of a bioequivalence study, the effect on bioequivalence decisions whether or not it is appropriate to eliminate them from the statistical evaluation of bioequivalence. MATERIALS AND METHODS: The clinical part was a cross-over, two periods, two sequences bioequivalence study concerning two piroxicam formulations, on healthy subjects. A simulation study evaluated the influence of 10% errors on the percent bias of calculated concentrations from nominal ones. RESULTS: In bioequivalence studies, it is not possible to distinguish between relevant types of outliers based only on statistical criteria. The "problem" is particularly acute when the omission of outliers leads to a bias in the decision concerning bioequivalence from rejection to acceptance. In such cases, there is the suspicion of subjective analysis and torture of data. The effect of analytical errors at high plasma levels was criticized for the calculated concentrations in the neighborhood of lower limit of quantification. Errors at low concentrations have a less significant effect. In the pharmacokinetic analysis, several types of outliers were shown: single points, curves, pairs of curves corresponding to the same subject, intrasubject ratios of areas under curves and maximum concentrations. These pharmacokinetic outliers could have had, at the same time, bioanalytical, physiological and physicochemical causes. CONCLUSION: Considering the results, it was proposed the following algorithm in the analysis of outlier data and outlier subjects in bioequivalence studies: evaluation of the implications of the decision concerning elimination of outliers on the decision concerning bioequivalence; application of the statistic tests for detection of outliers data; evaluations from the point of view of physiological pharmacokinetics, final decision concerning elimination of outliers.
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Algoritmos , Estudos Cross-Over , Humanos , Piroxicam , Equivalência TerapêuticaRESUMO
Captopril is the first angiotensin I-converting enzyme inhibitor widely used for the treatment of hypertension. Based on the well-known benefits of cyclodextrin inclusion complexes, the present study investigated the ability of ß-cyclodextrin to include captopril. Solid inclusion complexes of captopril with ß-cyclodextrin in a 1:2 molar ratio were prepared by using the paste method of complexation. For comparison purposes, a simple physical mixture with the same molar ratio was also prepared. Fourier-transform infrared spectroscopy, scanning electron microscopy, X-ray diffraction and simultaneous thermal analysis were used to characterize the raw materials, physical mixture and solid inclusion complex. In order to provide the drug in a more accessible and patient-compliant form following masking its bitter taste, as well as ensuring the appropriate release kinetics, the investigated complex was formulated as orally disintegrating tablets. The study of captopril dissolution in both compendial and simulated saliva media suggested the Noyes Whitney model as the best mathematical model to describe the release phenomena. A clinical study on healthy volunteers also highlighted the taste improvement of the new formulation as compared to conventional tablets.
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Due to its very low water solubility and complex pharmacokinetics, a reliable point-to-point correlation of its in vitro release with its pharmacokinetics has not been achieved so far with amiodarone. The correlation of the in vitro dissolution of a drug with the pharmacokinetics of one of its metabolites was recently proposed by the authors of the article as an additional or alternative analysis to the usual in vitro correlations in vivo, mainly in the case of fast-absorbing drugs that have metabolites with a significant therapeutic effect. The model proposed by the authors considers that amiodarone has a slow dissolution, rapid absorption, and rapid metabolism, and before returning to the blood from other compartments, its pharmacokinetics is determined mainly by the kinetics of release in the intestine from the pharmaceutical formulation. Under these conditions, the rate of apparition of desethylamiodarone in the blood is a metric of the release of amiodarone in the intestinal fluid. Furthermore, it has been shown that such an estimated in vivo dissolution is similar, after time scaling, to the dissolution measured experimentally in vitro. Dissolution data of amiodarone and the pharmacokinetic data of its active metabolite desethylamiodarone were obtained in a bioequivalence study of 24 healthy volunteers. The elimination constant of the metabolite from plasma was estimated as the slope of the linear regression of logarithmically transformed data on the tail of plasma levels. Because the elimination of desethylamiodarone was shown to follow a monoexponential model, a Nelson-Wagner-type mass equilibrium model could be applied to calculate the time course of the "plasma metabolite fraction." After Levi-type time scaling for imposing the in vitro-in vivo correlation, the problem became that of the correlation between in vitro dissolution time and in vivo dissolution time, which was proven to follow a square root model. To validate the model, evaluations were performed for the reference drug and test drug separately. In both cases, the scaled time for in vivo dissolution, t*, depended approximately linearly on the square root of the in vitro dissolution time t, with the two regression lines being practically parallel.
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In this study a novel type of in vitro-in vivo correlation (IVIVC) is proposed: The correlation of the in vitro parent drug dissolution data with the in vivo pharmacokinetic data of drug's metabolite after the oral administration of the parent drug. The pharmacokinetic data for the parent drug diltiazem (DTZ) and its desacetyl diltiazem metabolite (DTZM) were obtained from an in vivo study performed in 19 healthy volunteers. The pharmacokinetics of the parent drug and its metabolite followed a pseudomono-compartmental model and deconvolution of the DTZ or DTZM plasma concentration profiles was performed with a Wagner-Nelson-type equation. The calculated in vivo absorption fractions were correlated with the in vitro DTZ dissolution data obtained with USP 2 apparatus. A linear IVIVC was obtained for both DTZ and DTZM, with a better correlation observed for the case of the metabolite. This type of correlation of the in vitro data of the parent compound with the in vivo data of the metabolite could be useful for the development of drugs with active metabolites and prodrugs.
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The present paper continues a more complex research related to the increased synergism in terms of both anti-inflammatory and analgesic effect obtained by the addition of chlorpheniramine (CLF) to the common acetylsalicylic acid (ASA), acetaminophen (PAR), and caffeine (CAF) combination. This synergistic effect was previously highlighted both in vitro in rat models and in vivo in the treatment of migraine. The aim of the research was to further evaluate the analgesic effect of a synergistic low-dose ASA-PAR-CAF-CLF combination in the treatment of low back pain, in a parallel, multiple-dose, double-blind, active controlled clinical trial. A number of 89 patients with low back pain of at least moderate intensity were randomly assigned to receive Algopirin® (ALG), a combinational product containing 125 mg ASA, 75 mg PAR, 15 mg CAF, and 2 mg CLF, or PAR 500 mg, a drug recognized by American Pain Society as "safe and effective" in the treatment of low back pain. One tablet of the assigned product was administered three times a day for seven consecutive days. The patients evaluated their pain level using a Visual Analog Scale prior to administration, and at 1, 2, 4, and 6 h after the morning dose. Time course of effect was similar in structure and size for both treatments. Pain relief appeared rapidly and steadily increased over 4 h after drug administration. Differential pain curves of ALG and PAR were very similar and comparable with the previously determined ALG analgesia pattern in migraine. Differences between the daily mean pain scores were not statistically significant for the two treatments. Similar results were obtained for the Sum of Pain Intensity Differences (SPID) for 0-4 h and 0-6 h intervals as well as for the time course of the proportion of patients with at least 30% and at least 50% pain relief. In conclusion, in spite of very small doses of active components, ALG proved equally effective to the standard low back pain treatment and therefore a viable therapeutic alternative, mainly for patients with gastrointestinal and hepatic sensitivity. Trial Registration: www.ClinicalTrials.gov, identifier EudraCT No.: 2015-002314-74.
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Embedding of active substances in supramolecular systems has as the main goal to ensure the controlled release of the active ingredients. Whatever the final architecture or entrapment mechanism, modeling of release is challenging due to the moving boundary conditions and complex initial conditions. Despite huge diversity of formulations, diffusion phenomena are involved in practically all release processes. The approach in this paper starts, therefore, from mathematical methods for solving the diffusion equation in initial and boundary conditions, which are further connected with phenomenological conditions, simplified and idealized in order to lead to problems which can be analytically solved. Consequently, the release models are classified starting from the geometry of diffusion domain, initial conditions, and conditions on frontiers. Taking into account that practically all solutions of the models use the separation of variables method and integral transformation method, two specific applications of these methods are included. This paper suggests that "good modeling practice" of release kinetics consists essentially of identifying the most appropriate mathematical conditions corresponding to implied physicochemical phenomena. However, in most of the cases, models can be written but analytical solutions for these models cannot be obtained. Consequently, empiric models remain the first choice, and they receive an important place in the review.
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In this study, we investigated the release kinetic of fluorescein from colloidal liquid crystals made from monoglyceride and different non-ionic surfactants. The crystals were physicochemically characterized and the release experiments were carried out under the sink conditions, while mathematical models were described as extrapolations from solutions of the diffusion equation, in different initial and boundary conditions imposed by pharmaceutical formulations. The diffusion equation was solved using Laplace and Fourier transformed functions for release kinetics from infinite reservoirs in a semi-infinite medium. Solutions represents a general square root law and can be applied for the release kinetic of fluorescein from lyotropic colloidal liquid crystals. Akaike, Schwartz, and Imbimbo criteria were used to establish the appropriate mathematical model and the hierarchy of the performances of different models applied to the release experiments. The Fisher statistic test was applied to obtain the significance of differences among mathematical models. Differences of mathematical criteria demonstrated that small or no significant statistic differences were carried out between the various applied models and colloidal formulations. Phenomenological models were preferred over the empirical and semi-empirical ones. The general square root model shows that the diffusion-controlled release of fluorescein is the mathematical models extrapolated for lyotropic colloidal liquid crystals.
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The PHARMINE ("Pharmacy Education in Europe") project examined the organisation of pharmacy practice and education in the European Union (EU). An electronic survey was sent out to representatives of different sectors (community, hospital, industrial pharmacists, university staff, and students) in each individual EU member state. This paper presents the results of the PHARMINE survey on pharmacy practice and education in Romania. In the light of this data we examine to what extent harmonisation of practice and education with EU norms has occurred, whether this has promoted mobility of pharmacy professionals, academics and students, and what impact it has had on healthcare in Romania. The survey reveals the substantial changes in Romanian pharmacy practice and education since the 1989 change in government and Romania joining the EU in 2007. Romania remains, however, a poor country with expenditure on healthcare less than one-third of the EU average. This factor also impacts pharmacy practice. Although practice seems aligned with EU norms, this masks the substantial imbalance between the situation in the richer capital, Bucharest, and that of the poorer countryside. Harmonisation to EU norms in pharmacy education has not promoted student exchange and mobility but, rather, a brain drain in pharmaceutical graduates to other EU countries. Specialisation in industrial practice has been lost since 1989 with pharmacists being replaced by chemists. In hospitals the hospital pharmacist is being replaced by the clinical pharmacist.
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Previous studies indicated that addition of the antihistaminic chlorpheniramine to the usual combination of acetylsalicylic acid, acetaminophen, and caffeine further increases their synergism both in terms of anti-inflammatory and analgesic effect. The present non-interventional study tested the superiority of two Algopirin® tablets, containing a total of 250 mg acetylsalicylic acid (ASA), 150 mg acetaminophen (paracetamol, PAR), 30 mg caffeine (CAF) and 4 mg chlorpheniramine (CLF) vs. a combination containing 250 mg ASA, 250 mg PAR, and 65 mg CAF recognized as "safe and effective" by FDA in treating migraine. Patients evaluated their pain intensity on the Visual Analog Scale-VAS(PI) before and 30, 60, 120, 180, and 240 min after drug intake. Interpretation of the pain curves as "survival pain curves" was considered as a method for direct comparison of the pain curves. This interpretation permitted the application of the log rank test for comparison of pain hazards. The results of the applied parametric and non-parametric statistical tests indicated significant differences between the main endpoints: both Areas Under Pain Curves and time to decrease of the pain intensity to less than 50% of the initial value comparisons highlighted that Algopirin® was more efficient in spite of smaller doses of PAR and CAF. Comparison of "survival of pain" led to the same conclusion concerning the superiority of Algopririn. Consequently, the addition of CLF permitted decreasing of ASA, PAR, and CAF doses as well as their potential side effects, without a loss of analgesic effect.
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A trenchant and passionate dispute over the use of parametric versus non-parametric methods for the analysis of Likert scale ordinal data has raged for the past eight decades. The answer is not a simple "yes" or "no" but is related to hypotheses, objectives, risks, and paradigms. In this paper, we took a pragmatic approach. We applied both types of methods to the analysis of actual Likert data on responses from different professional subgroups of European pharmacists regarding competencies for practice. Results obtained show that with "large" (>15) numbers of responses and similar (but clearly not normal) distributions from different subgroups, parametric and non-parametric analyses give in almost all cases the same significant or non-significant results for inter-subgroup comparisons. Parametric methods were more discriminant in the cases of non-similar conclusions. Considering that the largest differences in opinions occurred in the upper part of the 4-point Likert scale (ranks 3 "very important" and 4 "essential"), a "score analysis" based on this part of the data was undertaken. This transformation of the ordinal Likert data into binary scores produced a graphical representation that was visually easier to understand as differences were accentuated. In conclusion, in this case of Likert ordinal data with high response rates, restraining the analysis to non-parametric methods leads to a loss of information. The addition of parametric methods, graphical analysis, analysis of subsets, and transformation of data leads to more in-depth analyses.
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The existence of a glucuronide conjugate of the major circulating clopidogrel metabolites, called clopidogrel acyl glucuronide (CAG), is already known. However, information regarding its pharmacokinetics (PK), metabolism, and clearance are modest. We investigated in vivo the potential CAG trans-esterification to clopidogrel (reaction occurring in vitro in particular conditions) by administering the metabolite to mice. Experiments were then carried out on men, clopidogrel administered alone or followed by activated charcoal intake (intestinal reabsorption blockade). Study objectives included: PK comparison of CAG, clopidogrel carboxylic acid (CCA), and clopidogrel in plasma, determination of their elimination patterns in urine and feces, and tracking of charcoal-induced changes in PK and/or urinary excretion that would indicate relevant enterohepatic recycling of CAG. In mice, CAG was rapidly hydrolyzed to CCA after oral administration, whereas by intravenous route metabolic conversion to CCA was delayed. No levels of clopidogrel were detected in mice plasma, excluding any potential trans-esterification or other form of back-conversion in vivo. PK experiments in man showed that CAG is hydrolyzed in the gastrointestinal tract (very low concentrations in feces), but there is no evidence of enterohepatic recirculation. Quantitation of the three moieties in stool samples accounted for only 1.2% of an administered dose, suggesting that other yet unknown metabolites/degradation products formed through metabolic processes and/or the activity of local microflora are mainly excreted by this route. In man CAG was confirmed as one of the major terminal metabolites of clopidogrel, with a PK behavior similar to CCA.
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Glucuronídeos/farmacocinética , Inibidores da Agregação Plaquetária/farmacocinética , Ticlopidina/análogos & derivados , Adolescente , Adulto , Animais , Clopidogrel , Feminino , Humanos , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Pessoa de Meia-Idade , Ticlopidina/farmacocinética , Adulto JovemRESUMO
European students (n = 370), academics (n = 241) and community pharmacists (n = 258) ranked 13 clusters of 68 personal and patient care competences for pharmacy practice. The results show that ranking profiles for all three groups as a rule were similar. This was especially true of the comparison between students and community pharmacists concerning patient care competences suggesting that students have a good idea of their future profession. A comparison of first and fifth (final) year students shows more awareness of patient care competences in the final year students. Differences do exist, however, between students and community pharmacists. Students-like academics-ranked competences concerned with industrial pharmacy and the quality aspects of preparing drugs, as well as scientific fundamentals of pharmacy practice, well above the rankings of community pharmacists. There were no substantial differences amongst rankings of students from different countries although some countries have more "medicinal" courses than others. This is to our knowledge the first paper to look at how, within a healthcare sectoral profession such as pharmacy, the views on the relative importance of different competences for practice of those educating the future professionals and their students, are compared to the views of working professionals.
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This paper looks at the opinions of 241 European academics (who provide pharmacy education), and of 258 European community pharmacists (who apply it), on competences for pharmacy practice. A proposal for competences was generated by a panel of experts using Delphi methodology. Once finalized, the proposal was then submitted to a large, European-wide community of academics and practicing pharmacists in an additional Delphi round. Academics and community pharmacy practitioners recognized the importance of the notion of patient care competences, underlining the nature of the pharmacist as a specialist of medicines. The survey revealed certain discrepancies. Academics placed substantial emphasis on research, pharmaceutical technology, regulatory aspects of quality, etc., but these were ranked much lower by community pharmacists who concentrated more on patient care competences. In a sub-analysis of the data, we evaluated how perceptions may have changed since the 1980s and the introduction of the notions of competence and pharmaceutical care. This was done by splitting both groups into respondents < 40 and > 40 years old. Results for the subgroups were essentially statistically the same but with some different qualitative tendencies. The results are discussed in the light of the different conceptions of the professional identity of the pharmacist.
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This paper looks at the way in which industrial pharmacists rank the fundamental competences for pharmacy practice. European industrial pharmacists (n = 135) ranked 68 competences for practice, arranged into 13 clusters of two types (personal and patient care). Results show that, compared to community pharmacists (n = 258), industrial pharmacists rank competences centering on research, development and production of drugs higher, and those centering on patient care lower. Competences centering on values, communication skills, etc. were ranked similarly by the two groups of pharmacists. These results are discussed in the light of the existence or not of an "industrial pharmacy" specialization.
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The objective of the PHAR-QA (Quality assurance in European pharmacy education and training) project was to investigate how competence-based learning could be applied to a healthcare, sectoral profession such as pharmacy. This is the first study on evaluation of competences from the pharmacists' perspective using an improved Delphi method with a large number of respondents from all over Europe. This paper looks at the way in which hospital pharmacists rank the fundamental competences for pharmacy practice. European hospital pharmacists (n = 152) ranked 68 competences for pharmacy practice of two types (personal and patient care), arranged into 13 clusters. Results were compared to those obtained from community pharmacists (n = 258). Generally, hospital and community pharmacists rank competences in a similar way. Nevertheless, differences can be detected. The higher focus of hospital pharmacists on knowledge of the different areas of science as well as on laboratory tests reflects the idea of a hospital pharmacy specialisation. The difference is also visible in the field of drug production. This is a necessary competence in hospitals with requests for drugs for rare diseases, as well as paediatric and oncologic drugs. Hospital pharmacists give entrepreneurship a lower score, but cost-effectiveness a higher one than community pharmacists. This reflects the reality of pharmacy practice where community pharmacists have to act as entrepreneurs, and hospital pharmacists are managers staying within drug budgets. The results are discussed in the light of a "hospital pharmacy" specialisation.