Clarice Madalena Bueno Rolim

Nanostructured systems containing an essential oil: protection against volatilization

The goal of this study was to evaluate the feasibility of preparing nanocapsules and nanoemulsions using tea tree oil as oily phase aiming to protect its volatilization. The nanostructures presented nanometric mean size (160-220 nm) with a polydispersity index below 0.25 and negative zeta potential. The pH values were 6.43 ± 0.37 and 5.98 ± 0.00 for nanoemulsions and nanocapsules, respectively. The oil content after preparation was 96%. The inclusion of tea tree oil in nanocapsules showed higher protection against volatilization. The analysis of mean size and polydispersity index of formulations presented no significant alteration during the storage time.

Development and validation of an UV spectrophotometric method for the determination of aliskiren in tablets

For determination of aliskiren in commercial samples, an analytical UV spectrophotometric method was developed and validate according to ICH guideline. The method was linear in the range between 40 and 100 μg mL-1 (r2 = 0.9997, n = 7) and exhibited suitable specificity, accuracy, precision, and robustness. It is simple, it has low cost, and it has low use polluting reagents. Therefore, the proposed method was successfully applied for the assay and dissolution studies of aliskiren in tablet dosage forms, and the results were compared to a validated RP-LC method, showing non-significant difference (P > 0.05).

PEGylated and poloxamer-modified chitosan nanoparticles incorporating a lysine-based surfactant for pH-triggered doxorubicin release

The growing demand for efficient chemotherapy in many cancers requires novel approaches in target-delivery technologies. Nanomaterials with pH-responsive behavior appear to have potential ability to selectively release the encapsulated molecules by sensing the acidic tumor microenvironment or the low pH found in endosomes. Likewise, polyethylene glycol (PEG)- and poloxamer-modified nanocarriers have been gaining attention regarding their potential to improve the effectiveness of cancer therapy. In this context, DOX-loaded pH-responsive nanoparticles (NPs) modified with PEG or poloxamer were prepared and the effects of these modifiers were evaluated on the overall characteristics of these nanostructures. Chitosan and tripolyphosphate were selected to form NPs by the interaction of oppositely charged compounds. A pH-sensitive lysine-based amphiphile (77KS) was used as a bioactive adjuvant. The strong dependence of 77KS ionization with pH makes this compound an interesting candidate to be used for the design of pH-sensitive devices. The physicochemical characterization of all NPs has been performed, and it was shown that the presence of 77KS clearly promotes a pH-triggered DOX release. Accelerated and continuous release patterns of DOX from CS-NPs under acidic conditions were observed regardless of the presence of PEG or poloxamer. Moreover, photodegradation studies have indicated that the lyophilization of NPs improved DOX stability under UVA radiation. Finally, cytotoxicity experiments have shown the ability of DOX-loaded CS-NPs to kill HeLa tumor cells. Hence, the overall results suggest that these pH-responsive CS-NPs are highly potent delivery systems to target tumor and intracellular environments, rendering them promising DOX carrier systems for cancer therapy.

Simultaneous determination of aliskiren and hydrochlorothiazide from their pharmaceutical preparations using a validated stability‐indicating MEKC method

A stability-indicating MEKC method was developed and validated for the simultaneous determination of aliskiren (ALI) and hydrochlorothiazide (HCTZ) in pharmaceutical formulations using ranitidine as an internal standard (IS). Optimal conditions for the separation of ALI, HCTZ and its major impurity chlorothiazide (CTZ), IS and degradation products were investigated. The method employed 47 mM Tris buffer and 47 mM anionic detergent SDS solution at pH 10.2 as the background electrolyte. MEKC method was performed on a fused-silica capillary (40 cm) at 28°C. Applied voltage was 26 kV (positive polarity) and photodiode array (PDA) detector was set at 217 nm. The method was validated in accordance with the ICH requirements. The method was linear over the concentration range of 5-100 and 60-1200 μg/mL for HCTZ and ALI, respectively (r(2) >0.9997). The stability-indicating capability of the method was established by enforced degradation studies combined with peak purity assessment using the PDA detection. Precision and accuracy evaluated by RSD were lower than 2%. The method proved to be robust by a fractional factorial design evaluation. The proposed MEKC method was successfully applied for the quantitative analysis of ALI and HCTZ both individually and in a combined dosage tablet formulation to support the quality control.

Validation of a simple and rapid UV spectrophotometric method for dexamethasone assay in tablets

This work reports the validation of an analytical UV spectrophotometric method to assay dexamethasone in tablets (assay and dissolution studies). The method was linear in the range between 1 and 30 µg mL-1 presenting a good correlation coefficient (r = 0.9998, n = 7). Precision and accuracy analysis showed low relative standard deviation (< 2.00%) and good percentual recoveries (95-105%). The procedure was linear, accurate, precise, and robust. The method is simple, and it has low cost. It does not use polluting reagents and can be applied in dissolution studies, being an adequate alternative to assay dexamethasone in tablets.

Novel Pullulan–Eudragit® S100 blend microparticles for oral delivery of risedronate: Formulation, in vitro evaluation and tableting of blend microparticles

Polymer blends have been considered a promising strategy to tailor drug release. In order to achieve gastroresistance and controlled release, Pullulan, a polysaccharide, and Eudragit® S100, an enteric polymer were selected to prepare microparticles for oral delivery of risedronate, an antiresorptive drug associated with GI tract injuries. Blend microparticles were prepared by spray-drying technique at 3 Pullulan and Eudragit® S100 ratios (MP2:1, MP1:1 and MP1:2) and were characterized in terms of yield, particle size, encapsulation efficiency, morphology, moisture content, flowability and in vitro drug release profiles. Microparticles presented yields between 31 and 42%, encapsulation efficiencies close to 100%, moisture contents lower than 11%, particle size ranging from 2.9 to 4.8 μm and narrow distribution. In the gastric medium, MP1:2 showed the best gastroresistance profile. In the intestinal fluid, all samples were able to prolong drug release. MP1:2 was compressed into tablets with or without polyvinylpyrrolidone. Both tableted microparticles could be obtained with acceptable average weights, drug content close to 100%, sufficient hardness and low friability. In vitro studies showed that tablets maintained the gastroresistance observed for microparticles and were also able to prolong risedronate release. In conclusion, Pullulan/Eudragit® S100 microparticles are promising alternatives for the oral delivery of risedronate in the future.

Nanoparticles incorporating pH-responsive surfactants as a viable approach to improve the intracellular drug delivery.

The pH-responsive delivery systems have brought new advances in the field of functional nanodevices and might allow more accurate and controllable delivery of specific cargoes, which is expected to result in promising applications in different clinical therapies. Here we describe a family of chitosan-TPP (tripolyphosphate) nanoparticles (NPs) for intracellular drug delivery, which were designed using two pH-sensitive amino acid-based surfactants from the family N(α),N(ε)-dioctanoyl lysine as bioactive compounds. Low and medium molecular weight chitosan (LMW-CS and MMW-CS, respectively) were used for NP preparation, and it was observed that the size distribution for NPs with LMW-CS were smaller (~168 nm) than that for NPs prepared with MMW-CS (~310 nm). Hemolysis assay demonstrated the pH-dependent biomembrane disruptional capability of the constructed NPs. The nanostructures incorporating the surfactants cause negligible membrane permeabilization at pH7.4. However, at acidic pH, prevailing in endosomes, membrane-destabilizing activity in an erythrocyte lysis assay became evident. When pH decreased to 6.6 and 5.4, hemolytic capability of chitosan NPs increased along with the raise of concentration. Furthermore, studies with cell culture showed that these pH-responsive NPs displayed low cytotoxic effects against 3T3 fibroblasts. The influence of chitosan molecular weight, chitosan to TPP weight ratio, nanoparticle size and nature of the surfactant counterion on the membrane-disruptive properties of nanoparticles was discussed in detail. Altogether, the results achieved here showed that by inserting the lysine-based amphiphiles into chitosan NPs, pH-sensitive membranolytic and potentially endosomolytic nanocarriers were developed, which, therefore, demonstrated ideal feasibility for intracellular drug delivery.

RAPID SIMULTANEOUS DETERMINATION OF ALISKIREN AND HYDROCHLOROTHIAZIDE FROM THEIR PHARMACEUTICAL FORMULATIONS BY MONOLITHIC SILICA HPLC COLUMN EMPLOYING EXPERIMENTAL DESIGNS

A simple, rapid, precise, and stability-indicating HPLC method was developed and validated for simultaneous determination of hydrochlorothiazide (HCTZ) and aliskiren (ALI) in pharmaceutical formulations. The HPLC method was carried out on a monolithic C18 column (100 mm × 4.6 mm id), maintained at 45°C. The mobile-phase consisted of acetonitrile-sodium phosphate (pH 4.0; 30 mM) (33:67, v/v), run at a flow rate of 2.4 mL/min, using photodiode array detection at 208 nm. Validation parameters such as the specificity, linearity, precision, accuracy, and robustness were evaluated according to the ICH guidelines. The method was linear in the range of 5–200 µg/mL (r2 > 0.9992) for both drugs. The specificity and stability indicating capability of the method were demonstrated through degradation studies, which also showed that there was no interference from the excipients. Plackett-Burman experimental design and a 23 full factorial design were employed to estimate the robustness and intermediate precision, respectively. The chromatographic separation was obtained within 2 min and it was suitable for high-throughput analysis. The proposed HPLC method was successfully applied for the simultaneous quantitative analysis of HCTZ and ALI in tablet dosage forms, contributing to improve the quality control and to assure the therapeutic efficacy.

Determination of Levofloxacin in a Pharmaceutical Injectable Formulation by Using HPLC and UV Spectrophotometric Methods

Abstract The objective of this study was to develop simple and rapid methods for the determination of levofloxacin (LVF) using high performance liquid chromatography and UV spectrophotometry. LVF was separated on a reversed phase Phenomenex® C18 column (150×4.6 mm i.d., particle size 4 µm), under isocratic elution with a mixture of water:acetonitrile:phosphoric acid 0.025 M, pH adjusted to 3.0 with triethylamine (60∶20∶20, v/v/v), as the mobile phase at room temperature and at a flow rate of 1.0 mL/min. The UV detector was set to 294 nm and UV‐vis spectrophotometer at 292 nm. Both methods allowed the quantification of LVF and showed good linearity (r>0.999) in the studied range. The relative standard deviations (RSD) were 0.66 and 1.0% for HPLC and UV spectrophotometry, respectively. The accuracy determined with HPLC was 100.68 and with UV spectrophotometry was 99.61%. The methods were validated through the parameters of linearity, accuracy, precision, specificity, and robustness. The two proposed methods enabled a quantitative determination of LVF in pharmaceutical injectable formulation.

Development and validation of a stability-indication LC-UV method for determination of daptomycin injectable form and kinetic study in alkaline medium

An isocratic liquid chromatography method (LC-UV) was developed and validated to determine daptomycin in injectable form. The method was carried out in a Waters XBridge C18 column (250 mm × 4.6 mm, 5 μm). The mobile phase was composed of methanol–acetonitrile–buffer (pH 2.2) (40 : 30 : 30 v/v/v) at a flow rate of 1.0 mL−1, using photodiode array (PDA) detection at 223 nm. The retention time obtained for daptomycin was 6.1 min and the method was linear in the range of 10 to 50 μg mL−1 (r = 0.9999). Forced degradation studies were performed to verify the specificity and stability-indicating capability of the method. The degradation kinetics under alkaline conditions were also evaluated. The method showed suitable accuracy (99.17%) and precision (RSD 0.59%) A two level full factorial design was used to determine the method robustness. The proposed method was applied for the analysis of daptomycin injectable form, contributing to the improvement of the quality control of this pharmaceutical product.