Cícero Flávio Soares Aragão

Application of Thermogravimetry in the Quality Control of Chloramphenicol Tablets

The stability and thermal behaviour of chloramphenicol and various of its mixtures were investigated. The thermogravimetric and stability constant results showed that the chloramphenicol base is thermally more stable than the tablet in the studied formulation. The reduction in stability was attributed to the presence of starch in the formulation. The thermal decompositions of the chloramphenicol base and the tablet obey first-order kinetics.

Application of thermal analysis to the study of antituberculosis drugs-excipient compatibility

First-line drugs (rifampicin, RIF; isoniazid, INH; ethambutol, ETA; and pyrazinamide, PZA) recommended in conventional treatment of tuberculosis were analyzed in 1:1 w/w binary mixtures with microcrystalline cellulose MC 101 (CEL) and lactose supertab® (LAC) by differential scanning calorimetry (DSC), thermogravimetry (TG), differential thermal analysis (DTA), and Fourier transformed infrared analysis (FTIR) as part of development of fixed dose combination (FDC) tablets. Evidence of interaction between drug and pharmaceutical excipients was supposed when peaks disappearance or shifting were observed on DTA and DSC curves, as well as decreasing of decomposition temperature onset and TG profiles, comparing to pure species data submitted to the same conditions. LAC was showed to interact with RIF (absence of drug fusion and recrystallization events on DSC/DTA curves); INH (thermal events of the mixtures different from those observed for drug and excipient pure in DSC/DTA curves); PZA (decrease on drug fusion peak in DSC/DTA curves), and ETA (shift on drug onset fusion and absence of pure LAC events on DSC/DTA curves). In all cases, an important decrease on the temperature of drug decomposition was verified for the mixtures (TG analysis). However, FTIR analysis showed good correlation between theoretical and experimental drug-LAC spectra except for INH–LAC mixture, evidencing high incompatibility between these two species and suggesting that those interactions with PZA and RIF were thermally induced. No evidence of incompatibilities in CEL mixtures was observed to any of the four-studied drugs.

Application of thermal analysis to the study of anti-tuberculosis drug compatibility. Part 1

Worldwide Brazil is among one of the 22 countries with high rates of tuberculosis placing this disease as a priority for the Government Health Policies in this country. Studies with the main tuberculostatic drugs rifampicin, isoniazid, pyrazinamide, and ethambutol, aiming the development of fixed-dose combination formulations (FDCs) have been performed. The aim of this study was to evaluate the thermal behavior of these drugs by DSC, TG/DTG, and DTA in order to predict possible physical and chemical interactions between tuberculostatics. DSC and DTA curves suggested incompatibility and/or interactions among drug preparations resulting from new thermal events, as well as the disappearance and shift of the melting point of the drugs. TG/DTG curves of drug mixtures presented different profiles from those observed for the individually tested drugs, supporting the evidence of drug incompatibility and indicating that mixtures are less stable when compared to the drugs alone.

Compatibility studies of trioxsalen with excipients by DSC, DTA, and FTIR

Psoralens are widely used for the treatment of psoriasis. Trioxsalen is a drug prescribed low-dose, belonging to the group of substituted psoralen. The aim of this study was to evaluate the compatibility of trioxsalen with pharmaceutical excipients used in the solid forms by analytical techniques. Binary mixtures between the trioxsalen and pharmaceutical excipients (namely, magnesium stearate, α-lactose, microcrystalline cellulose 102, pregelatinized starch, mannitol, sodium lauryl sulfate, sodium starch glycolate, and croscarmellose sodium) were examined. The trioxsalen–sodium lauryl sulfate mixture displayed some physical interaction based on the DTA and DSC results, but the FTIR study ruled out any chemical change.

Thermal Characterization of Warifteine by Means of TG and a DSC Photovisual System

This work proposes thermal characterization as analytical methodology for the identification and purity assay of warifteine, an alkaloid in Cissampelos sympodialis Eichl. Thermal and kinetic parameters were determined by means of TG and DSC photovisual studies. The TG results showed that the decomposition of warifteine in air and nitrogen atmospheres proceeds in three and four steps, respectively. The TG data allowed calculation of the kinetic parameters of warifteine. The activation energy values obtained by different methods displayed a good correlation. With the DSC photovisual system applied it is possible to detect the impurity level in warifteine after its purification.

Development of O/W emulsions containing Euterpe oleracea extract and evaluation of photoprotective efficacy

Euterpe oleracea Mart. is a palm tree popularly known as acai, which is primarily found in northern Brazil. The acais fruits contain anthocyanins, a class of polyphenols to which antioxidant properties have been attributed. The aim of this work was to develop O/W sunscreens emulsions containing acai glycolic extract (AGE) and to evaluate both their physical stability and photoprotective efficacy. Emulsions containing AGE and sunscreens were formulated using different types and concentrations of polymeric surfactant (acrylates/C 10-30 alkyl acrylate crosspolymer and sodium polyacrylate). The influence of two rheology modifiers (polyacrylamide (and) C13-14/isoparaffin (and) Laureth-7 and Carbomer) on the stability was also investigated. Physical stability was evaluated by preliminary and accelerated studies. Emulsions with 1.0% sodium polyacrylate were stable and exhibited non-newtonian pseudoplastic behavior and thixotropy. Photoprotective efficacy was evaluated by in vivo Sun Protection Factor (SPF) and determination of Protection Factor of UVA (PF-UVA). When AGE was added to the sunscreen emulsion, no significant increase in the in vivo SPF value was observed. The emulsion containing AGE showed PF-UVA = 14.97, 1.69 of the SPF/PF-UVA ratio and a critical wavelength value of 378 nm, and may therefore be considered a sunscreen with UVA and UVB protection.

Evaluation of the leishmanicide action of ethanol extracts of Crotalaria retusa L. (Fabaceae).

The purpose of the present work is to conduct an evaluation of the cytotoxicity of ethanol extracts and the total alkaloid fraction (TAF) from Crotalaria retusa for procyclic promastigotes cells of Leishmania chagasi. The kinetic study of extraction assisted by ultrasound of the total alkaloids present in Crotalaria retusa made it possible the optimization of the extraction parameters. It was evaluated the leishmanicide action of the TAF which did not show toxic activity for cells of the parasite in high concentrations. It was observed a powerful leishmanicide action of the ethanol extracts (10 and 30%) after the concentration of 5.6 mg/mL of Crotalaria retusa, and the ethanol present in the extractive solution (10 and 30%) in the concentration from 70 and 210 x 10-4 %, respectively. These results suggest that the cytotoxicity of the ethanol extract of Crotalaria retusa at 10 and 30% for cells of Leishmania chagasi, can be associated only to the concentration of the alcohol present in the extract.

Effect of paclitaxel (Taxol®) on the biodistribution of sodium pertechnetate (Na99mTcO4) in female Wistar rats

The evidence that natural or synthetic drugs can affect the biodistribution of radiopharmaceuticals (radiobiocomplexes) in setting of nuclear medicine clinic is already known. We studied the effect of Paclitaxel, an anti-neoplastic agent for the treatment of solid tumors, on the biodistribution of Na99mTcO4 in female rats. Paclitaxel (1mg/mL/week) was administered into animals in single dose during 3 weeks, with interval of 1 week among them. The control group received NaCl 0.9% solutions by the same via. One hour after the last dose, it was injected Na99mTcO4 in the animals. The percentage of activity per gram (%ATI/g) and biochemical and hematological determinations were performed. A significant increase were found in alanine aminotransferase, aspartate aminotransferase, glucose and in the %ATI/g of some organs (ovaries, uterus, vagina, breasts, large intestine and liver).These results can be associated, probably, to the capacity of paclitaxel to alter the biodistribution of Na99mTcO4 and the metabolism of glucose and hepatic enzymes.

Compatibility study between ferulic acid and excipients used in cosmetic formulations by TG/DTG, DSC and FTIR

Ferulic acid (4-hydroxy-3-methoxycinnamic acid) is a phytochemical constituent from the polyphenols group commonly found in whole grains, spinach, parsley, grapes and rhubarb. It has been widely applied in skin care formulations as photoprotective agent and delayer of cutaneous photoaging processes. This work aims to establish a protocol to the development of cosmetic formulations using thermoanalytical techniques (TG/DTG and DSC) and Pearson’s correlation by FTIR data, in order to evaluate the compatibility between ferulic acid and excipients used in skin care formulations. The results obtained from the thermoanalytical techniques indicated compatibility between ferulic acid and the following excipients: passion fruit seed oil, Carbopol® Ultrez 30, EDTA, Crodabase CR2®, Crodamol™ GTCC and Dow Corning® RM 2051. Nevertheless, the analysis also demonstrated the possibility of some interaction between ferulic acid and the following excipients: glyceryl stearate, Rapithix® A-60 and Optiphen®. To validate these results, it was demonstrated by Pearson’s correlation that passion fruit seed oil, Carbopol® Ultrez 30, EDTA, Crodabase CR2®, Crodamol™ GTCC, Dow Corning® RM 2051, glyceryl stearate and Rapithix® A-60 do not have any incompatibility that may compromise ferulic acid properties. Finally, it was also proved a meaningful incompatibility between ferulic acid and Optiphen® using Pearson’s correlation. Thus, it is not recommended to use Optiphen® in the development of cosmetic formulations to carry ferulic acid.

Development and Validation of HPLC-DAD and UHPLC-DAD Methods for the Simultaneous Determination of Guanylhydrazone Derivatives Employing a Factorial Design

Guanylhydrazones are molecules with great pharmacological potential in various therapeutic areas, including antitumoral activity. Factorial design is an excellent tool in the optimization of a chromatographic method, because it is possible quickly change factors such as temperature, mobile phase composition, mobile phase pH, column length, among others to establish the optimal conditions of analysis. The aim of the present work was to develop and validate a HPLC and UHPLC methods for the simultaneous determination of guanylhydrazones with anticancer activity employing experimental design. Precise, exact, linear and robust HPLC and UHPLC methods were developed and validated for the simultaneous quantification of the guanylhydrazones LQM10, LQM14, and LQM17. The UHPLC method was more economic, with a four times less solvent consumption, and 20 times less injection volume, what allowed better column performance. Comparing the empirical approach employed in the HPLC method development to the DoE approach employed in the UHPLC method development, we can conclude that the factorial design made the method development faster, more practical and rational. This resulted in methods that can be employed in the analysis, evaluation and quality control of these new synthetic guanylhydrazones.