Diclofenac quantification: analytical attributes of a spectrophotometric method

An spectrophotometric UV-visible technique used to quantify diclofenac and its application to pharmaceutical preparations is described, based on diclofenac oxidation by Fe(III) in the presence of ophenanthroline. The formation of tris (o-phenanthroline)-Fe(II) complex (ferroin) upon diclofenac reaction was investigated. Absorbance of ferroin complex was measured at 506 nm. This method was tested on 50 mg tablets. Operating with placebos, it was found that excipients do not interfere with the determination. A good linearity was found [y = (0.0294 ± 0.0041)x + (0.1326 ± 0.0559)] with r2 = 0.9982, calibration curve showed a linear range from 5-15 μg/mL of diclofenac. The proposed method was found to be highly precise, having a relative standard deviation (CV) below 2.0 % in repeatability and intermediate precision studies. Accuracy: based on the average recovery of known amounts of drug in placebo was 98.07-101.97 % values that fall within the requirements set by USP and ANMAT (98.0-102.0 %). This method was found to be simple, rapid, specific, linear, reliable and robust, allowing the determination without preliminary extraction procedures.Colegio de Farmacéuticos de la Provincia de Buenos Aire

Bullosis diabeticorum: a case report.

A case of an unusual bullous eruption (bullosis diabeticorum) occurring in a diabetic is reported. Clinical and histological features and possible pathogenetic mechanisms are discussed

Cinética de Disolución de Ciprofloxacina en Comprimidos. Comparación entre el Método de la Usp y Conductimetría

Se compara el seguimiento del perfil de disolución in vitro de ciprofloxacina en comprimidos a través del método establecido por la Farmacopea de los Estados Unidos, espectrofotometría UV y por conductimetría. Se aplica el procedimiento conductimétrico propuesto tanto a comprimidos de 500 mg. de ciprofloxacina elaborados por la Planta de Medicamentos de Corrientes (PLAME- COR) como a otro producto comercial de referencia considerado como equivalente farmacéutico. Se comprueba que el método para determinar cinética de disolución de ciprofloxacina por conductimetría otorga trazabilidad óptima para ser validado como procedimiento alternativo en los estudios de disponibilidad in vitro. Se suministran justificaciones que definen la conveniencia del método conductimétrico y su confiabilidad para decidir sobre la intercambiabilidad de este medicamento

Metformin reactivity with biuret: application to tablets

A spectrophotometric method was developed for the analysis of metformin, based on its reaction with the biuret reagent. A complex with λmax = 495 nm and stoichiometry 2:1 (metformin-Cu) is generated wich allows the quantification of metformin in tablets. Physicochemical parameters of the product were determined. Sample conditioning by centrifugation was necessary to separate insoluble excipients. Polyvinylpyrrolidone (PVP) was isolated by a solid-liquid extraction with SPE-SCX resin in order to eliminate its interference on the absorbance of the complex. The proposed method was found to be highly precise, having a relative standard deviation, CV % = 0.68. Using this approach the calibration curve showed r2 = 0.9949 with 95 % confidence level, value included inside the limits established by USP. Accuracy based on the average recovery of known amounts of drug in placebo was in the range of 98.61 to 99.97. Results allow the application of this analytical methodology to metformin tablets.Colegio de Farmacéuticos de la Provincia de Buenos Aire

Dosage of atenolol tablets by spectrophotometry with phenol red

A spectrophotometric method is proposed for the analysis of atenolol, based on its reaction with the indicator phenol red in an acetone environment. Experimental conditions for the formation of an ion pair complex peaking at 388 nm were optimized. The method is linear in the range of 1 to 5 mg/mL with a correlation coefficient (n = 30) of 0.9968. Stoichiometry of the reaction is 1: 1. Free energy change (ΔG) for complex formation and stability constant (KF) have been calculated. Working with placebo it was found that excipients do not interfere in the analysis. The proposed method was applied to tablets provided by the Medicinal Plant of Corrientes (Plamecor), Argentina. Recoveries from 99.67 to 100.17 were achieved. Results were compared (F test and t test) favorably with those given by official methods. (HPLC - UV).Colegio de Farmacéuticos de la Provincia de Buenos Aire

The multi-peak adaptive landscape of crocodylomorph body size evolution

Background: Little is known about the long-term patterns of body size evolution in Crocodylomorpha, the > 200-million-year-old group that includes living crocodylians and their extinct relatives. Extant crocodylians are mostly large-bodied (3–7 m) predators. However, extinct crocodylomorphs exhibit a wider range of phenotypes, and many of the earliest taxa were much smaller ( Results: Crocodylomorphs reached an early peak in body size disparity during the Late Jurassic, and underwent an essentially continual decline since then. A multi-peak Ornstein-Uhlenbeck model outperforms all other evolutionary models fitted to our data (including both uniform and non-uniform), indicating that the macroevolutionary dynamics of crocodylomorph body size are better described within the concept of an adaptive landscape, with most body size variation emerging after shifts to new macroevolutionary regimes (analogous to adaptive zones). We did not find support for a consistent evolutionary trend towards larger sizes among lineages (i.e., Cope’s rule), or strong correlations of body size with climate. Instead, the intermediate to large body sizes of some crocodylomorphs are better explained by group-specific adaptations. In particular, the evolution of a more aquatic lifestyle (especially marine) correlates with increases in average body size, though not without exceptions. Conclusions: Shifts between macroevolutionary regimes provide a better explanation of crocodylomorph body size evolution on large phylogenetic and temporal scales, suggesting a central role for lineage-specific adaptations rather than climatic forcing. Shifts leading to larger body sizes occurred in most aquatic and semi-aquatic groups. This, combined with extinctions of groups occupying smaller body size regimes (particularly during the Late Cretaceous and Cenozoic), gave rise to the upward-shifted body size distribution of extant crocodylomorphs compared to their smaller-bodied terrestrial ancestors.</p

Photography-based taxonomy is inadequate, unnecessary, and potentially harmful for biological sciences

The question whether taxonomic descriptions naming new animal species without type specimen(s) deposited in collections should be accepted for publication by scientific journals and allowed by the Code has already been discussed in Zootaxa (Dubois & Nemésio 2007; Donegan 2008, 2009; Nemésio 2009a–b; Dubois 2009; Gentile & Snell 2009; Minelli 2009; Cianferoni & Bartolozzi 2016; Amorim et al. 2016). This question was again raised in a letter supported by 35 signatories published in the journal Nature (Pape et al. 2016) on 15 September 2016. On 25 September 2016, the following rebuttal (strictly limited to 300 words as per the editorial rules of Nature) was submitted to Nature, which on 18 October 2016 refused to publish it. As we think this problem is a very important one for zoological taxonomy, this text is published here exactly as submitted to Nature, followed by the list of the 493 taxonomists and collection-based researchers who signed it in the short time span from 20 September to 6 October 2016

PHENOBARBITAL IN PHARMACEUTICAL TABLETS BY MODIFIED CONDUCTIMETRICAL ANALYSIS

Abstract A simple and reliable assay for Phenobarbital in tablets, by modified conductimetric titration was developed. The use of ammonium hydroxide addition enhanced the acidity of Phenobarbital and allowed its indirect determination, with NaOH as titrant. Optimal Work conditions were established to perform assays with tablets containing 100 mg of phenobarbital provided by the Medical Plant of Corrientes (PLAMECOR) Argentina. The proposed method was found to be highly precise, having a relative standard deviation (CV) below 2.0% in repeatability and intermediate precision studies. Using this approach the calibration curve showed r 2 = 0.9996 with a linearity range from 50 to 150 mg. Accuracy based on the average recovery of known amounts of drug in placebo was 100.15% ± 1.31, value included inside the limits established by USP. Trivial signal in titration of placebo demonstrated the high specificity of this method. Measurements were compared with determinations by the reference method (HPLC), using two tails Student`s statistical t-test. It C. M. Monzón et al. 102 was established with a 95% confidence level, that there are no significant differences among results obtained with both methods. The modified conductimetric titration method is preferred due to its simplicity, ease, low cost and absence of pre-treatment procedures of the samples Keywords: conductimetric titration, phenobarbital, pharmaceutical quality control Resumen Se desarrolló un método simple y confiable para la cuantificación de fenobarbital en comprimidos, por titulación conductimétrica modificada. La adición de amoníaco exalta la acidez del fenobarbital y permite su determinación indirecta, utilizando hidróxido de sodio como titulante. Se hallaron las condiciones óptimas de trabajo para efectuar el ensayo con tabletas de 100 mg de fenobarbital provistas por la Planta de Medicamentos de Corrientes, Argentina (PLAMECOR). El método propuesto es preciso, con valores del coeficiente de variación (CV) menores al 2,0% tanto en estudios de repetibilidad como de precisión intermedia. El rango lineal está comprendido entre 50 a 150 mg (r 2 = 0,9996). La exactitud, basada en la recuperación promedio de cantidades conocidas de la droga pura sobre placebo de 100,15 % ± 1,31 está incluida dentro de los límites establecidos por la Farmacopea de los Estados Unidos (USP). La señal despreciable obtenida en la titulación del placebo demuestra la especificidad del ensayo. Se efectuaron comparaciones con el método de referencia (HPLC), usando el test t de Student de dos colas. Se estableció, con el 95% de confianza, que no hay diferencia significativa entre los resultados obtenidos por ambos métodos. El método de titulación conductimétrica modificado es simple, de bajo costo y no son necesarios procedimientos de tratamiento previo de las muestras