A sustainable UPLC-UV method for quantification of donepezil hydrochloride in biorelevant media applied to dissolution profile comparison.

Donepezil hydrochloride is one of the most prescribed anti-Alzheimer's drugs, despite being available for more than two decades, chromatographic methods for the quantification of the drug in biorelevant media that mimics pH physiological conditions in vivo (pH 1.2, 4.5, and 6.8) are not available in the literature. These media are used in the dissolution test, an important tool, for registration and quality control of medicines. Considering the need for methods with this purpose, this work aimed to develop and validate a sustainable UPLC-UV method for quantification of donepezil hydrochloride in tablets, specifically on assay and dissolution profile, with reduced environmental impacts. The proposed method has a run time of 2 min and requires for each run, only 0.8 mL of solvents, providing excellent green analysis. The method proved to be selective, linear, precise, accurate, robust in the range of 2-14 µg/mL. Three products (reference, similar, and generic) were analyzed and showed very rapid dissolution. The average content varied from 100.2 ± 0.6% to 109.5 ± 2.1%. Using dissolution efficiency (DE), the drug release profiles were compared in different biorelevant media.

Evaluation of the losartan solubility in the biowaiver context by shake-flask method and intrinsic dissolution.

This study aimed at evaluating the shake-flask use as a universal method to evaluate drug solubility in a biowaiver context as proposed by FDA, EMA and ANVISA. The solubility of losartan was determined in three buffers using the shake-flask method, intrinsic dissolution (ID) and Quantum Chemistry. Moreover, the evaluation of a losartan dissolution profile from coated tablets was conducted. The losartan low solubility in pH 1.2 and high solubility in pH 6.8 were observed using the shake-flask method. However, the solubility results using ID demonstrated its high solubility in pH 1.2 and 6.8. It was not possible to find conclusive results regarding the solubility of the drug in pH 4.5. The studies conducted by Quantum Chemistry provide molecular and electronic data that helped understand the losartan solvation in different pH values. Our experimental results defined that losartan can be classified as a low-solubility drug. In addition, this work shows that shake-flask cannot be a universal method of solubility studies in biowaiver context. Individual analysis will be necessary. The intrinsic dissolution should be considered as a complementary method.

Polymorphic and Quantum Chemistry Characterization of Candesartan Cilexetil: Importance for the Correct Drug Classification According to Biopharmaceutics Classification System.

The recommended method for the biopharmaceutical evaluation of drug solubility is the shake flask; however, there are discrepancies reported about the solubility of certain compounds measured with this method, one of them is candesartan cilexetil. The present work aimed to elucidate the solubility of candesartan cilexetil by associating others assays such as stability determination, polymorphic characterization and in silico calculations of intrinsic solubility, ionized species, and electronic structures using quantum chemistry descriptors (frontier molecular orbitals and Fukui functions). For the complete biopharmaceutical classification, we also reviewed the permeability data available. The polymorphic form used was previously identified as the form I of candesartan cilexetil. The solubility was evaluated in biorelevant media in the pH range of 1.2-6.8 at 37.0°C according to the stability previously assessed. The solubility of candesartan cilexetil is pH dependent and the dose/solubility ratios obtained demonstrated the low solubility of the prodrug. The in silico calculations supported the found results and evidenced the main groups involved in the solvation, benzimidazole, and tetrazol-biphenyl. The human absolute bioavailability reported demonstrates that candesartan cilexetil has low permeability and when associated with the low solubility allows to classify it as class 4 of the Biopharmaceutics Classification System.

Folic acid: a biopharmaceutical evaluation.

The aqueous solubility and drug product dissolution are important factors that determine the rate and extent of drug absorption from immediate release solid oral dosage forms. The aim of this article was to perform a folic acid biopharmaceutical study to evaluate the biowaiver of new products containing folic acid. We studied the solubility of its raw material and the dissolution profile of two commercially available products. Three different buffers (pH 1.2, 4.5 and 6.8) were used as the media of the solubility and dissolution tests (apparatus II, at 50 rpm and 900 mL of medium volume). We found that folic acid solubility and its release from tablets are pH dependent. The dissolution profiles of both tablets were compared by dissolution efficiency (%), using t-test or variance analysis (ANOVA). The dissolution profiles obtained for the two products at pH 1.2 medium were similar (p > 0.05), but they were dissimilar at pH 4.5 and 6.8 (p < 0.05). Furthermore, we could observe differences between all the dissolution profiles of folic acid for each product at three different dissolution media used. The results showed that physicochemical characteristics of folic acid affect its dissolution and absorption making it difficult to take a decision on their biowaiver based on BCS.

Development and characterization of multilamellar liposomes containing pyridostigmine.

Pyridostigmine has cardioprotective activity in both free and liposomal forms. This study aimed to develop and characterize liposomal formulations of pyridostigmine. For this, a spectrophotometric ultraviolet (UV) analytical method, at 270 nm, was developed and validated to quantify liposomal pyridostigmine. The method was linear in ranges from 0.02 to 0.09 mg/mL. The accuracy of this method was determined intra- and inter-day; the results of coefficient of variation were of 1.73-2.72% and 0.32-2.32%, respectively. The accuracy ranged between 99.45% and 101.12%. The method has not changed by influence of liposomal matrix and demonstrated being able to quantify pyridostigmine in liposomes. Two liposomal multilamellar formulations were developed: a constituted by dystearoyl-phosphatidylcholine (DSPC) and cholesterol (CHOL) other by dioleil-phosphatidylcholine (DOPC) and CHOL. The encapsulation efficiency was determined as 23.4% and 15.4%, respectively. Analyses of size and release of pyridostigmine from the formulations were made and the results showed that the formulations are viable for future studies in vivo.

Preclinical monitoring of drug association in experimental chemotherapy of Chagas' disease by a new HPLC-UV method.

A combination of drugs in experimental chemotherapy of Chagas' disease may increase the effectiveness of treatment. To evaluate the possible mechanisms that influence the improvement of therapy, we investigated the pharmacokinetic interaction between benznidazole and itraconazole in a murine model treated orally with single doses of 5 mg of each compound separately or together. Blood samples from treated mice were collected at different intervals for 48 h, and a high-performance liquid chromatography (HPLC)-UV method was used to quantify both drugs in the plasma. A decrease of 1.5-fold in the maximum drug concentration in the plasma (C(max)) and an increase of 2.66-fold in the volume of distribution (V) and 7.5-fold in the elimination half-life (t(1/2ß)) of benznidazole when coadministered with itraconazole were observed. The parameters area under the curve (AUC(0-t)), area under the curve extrapolated to infinity (AUC(0-∞)), time to maximum concentration of drug in serum (T(max)), and clearance (CL) for benznidazole were not significantly different in this therapeutic regime. None of the evaluated parameters for ITC demonstrated a significant difference between isolated and associated administration. These results suggest that the main effect of this interaction leads to accumulation of benznidazole in the biological system. This effect may contribute to the improved therapeutic efficacy of this combination of drugs, in addition to synergism of the different mechanisms of action of benznidazole and itraconazole against Trypanosoma cruzi in vivo.

Donepezil Hydrochloride BCS Class Ambiguity: Relevant Aspects to be Considered in Drug Classification.

Donepezil hydrochloride (DH) is the most used anti-Alzheimer's disease drug, however, its classification according to the Biopharmaceutics Classification System (BCS) is not clear in the literature. BCS is one of the accepted criteria used to grant biowaiver (waiver of in vivo bioequivalence studies) of new drug products. So, the purpose of this work was to elucidate the BCS classification of DH and to raise the discussion about the possibility of biowaiver for new medicines containing it. The polymorphic form was previously identified as form III of DH. The drug showed high solubility in the entire pH range evaluated (1.2 to 6.8, at 37 °C) with a pH-dependent solubility profile. The effective permeability (Peff) values obtained with different DH concentrations, using in situ closed-loop perfusion model were statistically similar (p > 0.05), even when compared to high permeability control used (ketoprofen), demonstrating that DH has high permeability which, associated with its high solubility, allows to classify DH as BCS class 1. Relevant data to evaluate for granting a biowaiver for new medicines were also reviewed from the literature. Based on information reunited new immediate-release drug products containing DH should be eligible for BCS-based biowaiver.

Patient safety in primary health care and polypharmacy: cross-sectional survey among patients with chronic diseases.

OBJECTIVE: to characterize and determine the polypharmacy prevalence in patients with chronic diseases and to identify the factors associated, in order to improvement of pharmaceutical care focused on patient safety. METHODS: cross-sectional study included 558 patients, covered by primary health care, using a household and structured questionnaire. We analyzed the data on polypharmacy and its clinical and socioeconomic factors. Poisson regression analysis with robust variance was applied, with results expressed in prevalence ratio. RESULTS: the results showed that polypharmacy (consumption of four or more drugs) was of 37.6%. The prevalence ratio analyses identified independent variables associated with polypharmacy: age (3.05), economic strata (0.33), way of medication acquisition through a combination of out-of-pocket and Brazilian public health system (1.44), diabetes and hypertension (2.11), comorbidities (coronary artery disease 2.26) and hospital admission (1.73). In the analyses, inappropriate medication use of the 278 patients (≥ 65 years) was associated with polypharmacy (prevalence ratio 4.04). CONCLUSION: polypharmacy study becomes an opportunity to guide the strategies for the patient safety to promote the medication without harm in chronic diseases.

Effects of experimental conditions on solubility measurements for BCS classification in order to improve the biowaiver guidelines

Among the methods described for determining the solubility, shake-flask is suitable to evaluate the equilibrium solubility according to the BCS. Nevertheless, experimental conditions related to the shake-flask method are not well described. Evaluating the effects of experimental conditions on solubility measurements by shake-flask method is important and contributes in biowaiver decision. For this work, propranolol hydrochloride and nimesulide were used as model compound of high and low solubility, respectively. Equilibrium solubility was evaluated at 37 ºC, 100 rpm during 48 hours in buffer media. Effects of the rotation speed, temperature, substance in excess and aliquot withdrawn were evaluated. Small variations of temperature caused significant differences in the solubility and then this parameter must be controlled. Excess of raw material influenced the results of the nimesulide, then, little excess is recommended. Rotation speed did not cause differences in the equilibrium solubilities, but at 150 rpm the equilibrium was reached faster. Aliquot did not present significant differences, but excessive withdrawn should be avoided. Therefore, the evaluation of equilibrium solubility using shake-flask method must be performed in physiological pH conditions, 37 ± 1 ºC, substance in excess 10% above saturation, 50, 100 or 150 rpm and aliquot withdrawn not more than 10% of the media volume.

Prolonged cardioprotective effect of pyridostigmine encapsulated in liposomes.

AIMS: The purpose of the present work was to investigate the ability of pyridostigmine encapsulated in long-circulating liposomes, to protect against ECG (electrocardiogram) alterations induced by sympathetic stimulation in rats. MAIN METHODS: The encapsulation of pyridostigmine was carried out by freeze-thaw and extrusion. Blood pressure and ECG (limb lead II) were monitored in anaesthetized male Wistar rats. The formulation containing pyridostigmine was intravenously administrated in 0.1, 0.3 and 1.0mg/kg doses, and sympathetic stimulation was conducted by administration of 1 or 3 microg of noradrenaline (NA) after 1, 2, 4 or 6h. The obtained cardiovascular parameters were compared to animals that received intravenous injection of pyridostigmine in free form or saline. KEY FINDINGS: After saline, NA induced a significant increase in QT interval (22.3% after 3.0 microg). Previous administration of free pyridostigmine significantly prevented the increase of QT interval after sympathetic stimulation and the most prominent effect was observed after 1h for the dose of 0.3mg/kg (6.8% after 3.0 microg of NA) and was no longer observed after 2h of the treatment. On the other hand, the maximum effect of pyridostigmine in liposomal formulation preventing QT interval increase was observed 2h after treatment (9.7% after 3.0 microg of NA) and was still present until 6h when 1mg/kg was previous administrated. SIGNIFICANCE: The results of the present study, beyond to confirm the cardioprotective action of pyridostigmine, suggest that liposomal pyridostigmine may be a potential therapeutic alternative to prevent cardiovascular disturbances resulting from sympathetic hyperactivity.

Profile of wound healing process induced by allantoin.

PURPOSE: To evaluate and characterize the wound healing process profile induced by allantoin incorporated in soft lotion oil/water emulsion using the planimetric and histological methods. METHODS: Female Wistar rats (n=60) were randomly assigned to 3 experimental groups: (C) control group-without treatment; (E) group treated with soft lotion O/W emulsion excipients; (EA) group treated with soft lotion O/W emulsion containing allantoin 5%. The emulsions either containing or not allantoin were topically administered for 14 days and the wound area was evaluated by planimetry and by qualitative and quantitative histological analysis of open wound model. RESULTS: The data which were obtained and analyzed innovate by demonstrating, qualitatively and quantitatively, by histological analysis, the profile of healing process induced by allantoin. The results suggest that the wound healing mechanism induced by allantoin occurs via the regulation of inflammatory response and stimulus to fibroblastic proliferation and extracellular matrix synthesis. CONCLUSION: This work show, for the first time, the histological wound healing profile induced by allantoin in rats and demonstrated that it is able to ameliorate and fasten the reestablishment of the normal skin.

Biopharmaceutics classification system: importance and inclusion in biowaiver guidance

Pharmacological therapy is essential in many diseases treatment and it is important that the medicine policy is intended to offering safe and effective treatment with affordable price to the population. One way to achieve this is through biowaiver, defined as the replacement of in vivo bioequivalence studies by in vitro studies. For biowaiver of new immediate release solid oral dosage forms, data such as intestinal permeability and solubility of the drug are required, as well as the product dissolution. The Biopharmaceutics Classification System (BCS) is a scientific scheme that divides drugs according to their solubility and permeability and has been used by various guides as a criterion for biowaiver. This paper evaluates biowaiver application, addressing the general concepts and parameters used by BCS, making a historical account of its use, the requirements pertaining to the current legislation, the benefits and risks associated with this decision. The results revealed that the use of BCS as a biowaiver criterion greatly expands the therapeutics options, contributing to greater therapy access of the general population with drug efficacy and safety guaranteed associated to low cost.

O tratamento farmacológico é essencial frente a várias patologias e é fundamental que a política de medicamentos tenha por objetivo oferecer à população tratamento seguro, eficaz e de preço acessível. Uma forma de alcançar esse objetivo é por meio da bioisenção, definida como a substituição de estudos de bioequivalência in vivo por estudos in vitro. Para bioisentar novos medicamentos sob a forma farmacêutica sólida oral de liberação imediata são utilizados dados de permeabilidade intestinal e solubilidade do fármaco, bem como sua dissolução a partir da forma farmacêutica. O Sistema de Classificação Biofarmacêutica (SCB) é um esquema científico que divide os fármacos em classes de acordo com a solubilidade e permeabilidade e vem sendo utilizado como critério para bioisenção em diversas legislações. O presente artigo faz uma avaliação da aplicação da bioisenção, abordando os conceitos gerais e parâmetros utilizados pelo SCB, fazendo um relato histórico da aplicação da bioisenção, das exigências pertinentes às legislações vigentes, dos benefícios e riscos inerentes a uma tomada de decisão sobre bioisenção baseada neste critério. Os resultados revelaram que a utilização do SCB como critério amplia enormemente as possibilidades de bioisenção, contribuindo para o maior acesso da população em geral a medicamentos com garantida eficácia, segurança e menor custo.

Profile of wound healing process induced by allantoin / Perfil do processo de cicatrização induzido pela alantoína

PURPOSE: To evaluate and characterize the wound healing process profile induced by allantoin incorporated in soft lotion oil/water emulsion using the planimetric and histological methods. METHODS: Female Wistar rats (n=60) were randomly assigned to 3 experimental groups: (C) control group-without treatment; (E) group treated with soft lotion O/W emulsion excipients; (EA) group treated with soft lotion O/W emulsion containing allantoin 5 percent. The emulsions either containing or not allantoin were topically administered for 14 days and the wound area was evaluated by planimetry and by qualitative and quantitative histological analysis of open wound model. RESULTS: The data which were obtained and analyzed innovate by demonstrating, qualitatively and quantitatively, by histological analysis, the profile of healing process induced by allantoin. The results suggest that the wound healing mechanism induced by allantoin occurs via the regulation of inflammatory response and stimulus to fibroblastic proliferation and extracellular matrix synthesis. CONCLUSION: This work show, for the first time, the histological wound healing profile induced by allantoin in rats and demonstrated that it is able to ameliorate and fasten the reestablishment of the normal skin.

OBJETIVO: Avaliar e caracterizar o perfil cicatricial induzido pela alantoína incorporada em uma emulsão óleo/água, sob os aspectos planimétrico e histológico. MÉTODOS: Ratos Wistar fêmeas (n=60) foram agrupados aleatoriamente em três grupos experimentais grupo controle - sem tratamento (C); grupo tratado com emulsão pura (E); grupo tratado com emulsão contendo 5 por cento de alantoína (EA). As emulsões contendo ou não alantoína foram administradas topicamente durante 14 dias e a área da ferida foi avaliada por planimetria e por análise histológica qualitativa e quantitativa em modelo de ferida aberta. RESULTADOS: Na análise planimétrica não foi observado diferenças significativas entre os grupos experimentais. Os resultados da análise histológica sugerem que o mecanismo de cicatrização induzido pela alantoína ocorre via controle da resposta inflamatória e estímulos à proliferação fibroblástica e síntese de matrix extracelular de maneira mais intensa e rapidamente em relação aos grupos controles. CONCLUSÃO: Este trabalho mostra pela primeira vez o perfil histológico de cicatrização induzido pela alantoína em ratos, demonstrando ser capaz de melhorar e acelerar o processo de reconstituição da pele.

Schistosomidal activity of oxamniquine encapsulated in stericallly stabilized liposomes / Atividade esquistosomicida da oxamnique encapsulada em lipossomas estabilizados estericamente

A droga esquistosomicida, oxamniquine (OXA), foi encapsulada em lipossomas estabilizados estericamente (LOXA) e avaliada em camundongos infectados por cinco semans com schistosoma mansoni. LOXA, quando administrada por via intraperitoneal, mostrou a mesma eficiência na reduçäo do número de parasitos que OXA livre. Este dado estabelece a eficiência de LOXA, mas indica também que a encapsulaçäo da OXA em lipossomas estabilizados estericamente näo resultou no aumento de sua atividade. O fato de LOXA ser mais eficiente for via intraperitoneal que por via subcutânea sugere que os lipossomas estabilizados estericamente têm que entrar rapidamente na circulaçäo sangüínea para atingir o parasito