ABSTRACT The oral solid dosage forms are extremely relevant to drug therapy and responsible for much of the pharmaceutical industry turnover worldwide. However, the development of medicines in solid form involves significant challenges, including obtaining formulations with appropriate bioavailability for low aqueous solubility drugs (classes II and IV of the Biopharmaceutics Classification System). One of the most effective strategies to overcome poor dissolution rate and low absorption of drugs is the solid dispersion technique, however, although it has been the focus of much research in recent decades, there are relatively few commercially available products based on such technology. This is mainly due to problems related to production scale-up and physicochemical instability and creates opportunities for new studies to explore the full potential of the technology. This review presents an overall approach to the factors affecting the dissolution rate and oral bioavailability of BCS-classes II and IV drugs and a brief review of the state-of-theart of solid dispersion technology.

<p>In this study, nifedipine (NFP)-loaded polymeric nanocapsules were prepared and characterised with a view to protect the drug from degradation. Nanocapsule suspensions were prepared using two different surfactants (pluronic F68 and polyvinyl alcohol). Physicochemical stability and <italic>in vivo</italic>antihypertensive effect were evaluated. The particle size, zeta potential and entrapment efficiency remained constant during a period of 28 days of exposure under light irradiation. A smaller particle size and a higher zeta potential were obtained for the nanocapsules prepared with Pluronic F68 as surfactant. The solid drug and the nanocapsules were submitted to light exposure for 28 days. After this period of time, the percentage of drug remaining in the PF68NFP and PVANFP nanocapsules was 28.1% and 21.3%, respectively. In contrast, the solid drug was completely degraded after 4 days, suggesting that the nanocapsule suspensions promoted significant protection of the drug against light exposure. In addition, <italic>in vivo</italic> studies were carried out, which demonstrated that the formulations with polyvinyl alcohol exhibited a very rapid onset of action after oral administration in rats and led to faster drug release. The nanoparticles developed can be considered as an alternative for improving NFP stability in liquid formulations.</p>

This paper reports the development and validation of a new analytical method using UV spectrophotometry to quantify carvedilol (CRV) in hydrophilic matrices and raw material. This method was shown to be linear, accurate, precise, robust and to have adequate limits of quantification and detection (LQ and LD, respectively), allowing its use in the dissolution test of hydrophilic matrices. The content of CRV determined through this method was compared with two previously validated methods based on the reference techniques of High Performance Liquid Chromatography (HPLC) and Potentiometric Titrations (PT). ANOVA confirmed the equivalence of these methods, showing no significant differences.

The aim of this study was to encapsulate curcumin into chitosan, using sodium tripolyphosphate (TPP) as an ionic crosslinker by the spray drying method. The influence of TPP on the properties of the final product, such as solubility, morphology, loading efficiency, thermal behavior, swelling degree and release profiles, was evaluated. The microparticles had a spherical morphology (0.5-20 µm) with no apparent porosity or cracks. Results indicated the formation of a polymeric network, which ensures effective protection for curcumin. Controlled-release studies were carried out at pH 1.2 and 6.8, to observe the influence of pH on curcumin release while the mechanism was analyzed using the Korsmeyer-Peppas equation.

This work reports the validation of an analytical UV spectrophotometric method to assay acyclovir in hydrophilic matrices (assay and dissolution studies). The method was linear in the range between 2.5-20 µg mL-1, presenting a good correlation coefficient ( r = 0,9999). Precision and accuracy analysis showed low relative standart deviation (< 2.0 %) and a good recoveries percentual (98.9-100 %). The procedure was linear, accurate, and robust. The method is simple and cheap. It does not use polluting reagents and can be applied in dissolution studies, being an adequate alternative to assay acyclovir in hydrophilic matrices tablets.

An analytical method using an ultraviolet spectroscopy (UV) was developed and validated to quantify the drug captopril in tablets of delayed release. The available parameters were: specificity, linearity and range, precision, accuracy and robustness. The linearity in the range of 5.0 - 40.0 µg/mL presented a correlation coefficient of 0, 9998. The excipients in the formulation did not interfere with the analysis and the recovery was quantitative 100, 20 ± 0, 28%. All results were satisfactory and the method proved to be adequate to quantify captopril in delayed release tablets.

Um método analítico utilizando espectroscopia no ultravioleta (UV) foi desenvolvido e validado para quantificar o fármaco captopril em comprimidos de liberação prolongada. Os parâmetros utilizados no processo de validação foram especificidade, linearidade e intervalo, precisão, exatidão e robustez. A linearidade no intervalo de 5.0 - 40.0 µg/mL apresentou um coeficiente de correlação de 0,9998. Os excipientes das formulações não interferiram com a análise e a recuperação da amostra foi de 100,20 ± 0,28 %. Todos os resultados foram satisfatórios e o método provou ser adequado para quantificar o captopril nos comprimidos de liberação prolongada.