Raman spectroscopy as a complementary tool to assess the content uniformity of dosage units in break-scored warfarin tablets.

Due to the side effects of overdosing, the therapeutic dose of warfarin preparations must be very strictly controlled. In order to make it easier for the patient to take the required dose, two different strategies can be followed: The medicine can be commercialized in different dosages and/or tablets can be scored in order to make them easy to split. The splitting of the tablets introduces the question of how to control that the fractions contain the desirable amount of warfarin. The regulations regarding the content uniformity of dosage unit for scored tablets have changed considerably in the last 10 years, and they are still evolving. Warfarin is commercialized under the trademark of Aldocumar in four different preparations, containing 1, 3, 5 and 10 mg sodium warfarin per tablet. All these tablets are also scored, thus suggesting the possibility of splitting. A quantitative Raman method has been developed for the determination of warfarin in tablets and in the potential fragments, taking into account the score lines on the tablet surface. This method is suggested as an auxiliary procedure to verify the uniformity of API distribution in dividable tablets. A combination of a second derivative and standard normal variate (SNV) was used as spectral pre-treatments, and partial least squares (PLS) as the regression algorithm. The relative standard deviation in API content among portions was found to be less than 5%. An HPLC procedure has been used as a reference analytical method.

Multi-wavelength high-performance liquid chromatographic fingerprints and chemometrics to predict the antioxidant activity of Turnera diffusa as part of its quality control.

The determination of the antioxidant activity of Turnera diffusa using partial least squares regression (PLSR) on chromatographic data is presented. The chromatograms were recorded with a diode array detector and, for each sample, an enhanced fingerprint was constructed by compiling into a single data vector the chromatograms at four wavelengths (216, 238, 254 and 345 nm). The wavelengths were selected from a contour plot, in order to obtain the greater number of peaks at each of the wavelengths. A further pretreatment of the data that included baseline correction, scaling and correlation optimized warping was performed. Optimal values of the parameters used in the warping were found by means of simplex optimization. A PLSR model with four latent variables (LV) explained 52.5% of X variance and 98.4% of Y, with a root mean square error for cross validation of 6.02. To evaluate its reliability, it was applied to an external prediction set, retrieving a relative standard error for prediction of 7.8%. The study of the most important variables for the regression indicated the chromatographic peaks related to antioxidant activity at the used wavelengths.

Enhanced chromatographic fingerprinting of herb materials by multi-wavelength selection and chemometrics.

A strategy for multi-wavelength chromatographic fingerprinting of herbal materials, using high performance liquid chromatography with a UV-Vis diode array detector is presented. Valeriana officinalis was selected to show the proposed methodology since it is a widely used commercially available herbal drug, and because misfit with other valerian species is a current issue. The enhanced fingerprints were constructed by compiling into a single data vector the chromatograms from four wavelengths (226, 254, 280 and 326 nm), at which characteristic chemical constituents of studied herbs presented maximum absorbance. Chromatographic data pretreatment included baseline correction, normalization and correlation optimized warping. A simplex optimization was performed to retrieve the optimal values of the parameters used in the warping. General success rates of a classification above 90% were achieved by soft independent modeling of class analogy (SIMCA) and partial least squares discriminant analysis (PLS-DA). The sensitivity and specificity of constructed models were above 94%. Tests on laboratory-made mixtures showed that it is possible to detect adulterations or counterfeits with 5% foreign herbal material, even if it is from the Valerianaceae family. The results suggest that the proposed enhanced fingerprinting approach can be used to authenticate herb materials with complex chromatographic profiles.

Enhancing sensitivity and precision on NIR reflectance determination of an API at low concentration: Application to an hormonal preparation.

The use of a mixed calibration sample set (intact production tablets and powdered doped samples used to enlarge calibration range) is a usual procedure for the NIR reflectance determination of the API content of a pharmaceutical solid preparation. However, the high difference in scattering properties and the intrinsic low sensitivity of NIR make difficult the achievement of a good precision when API is at a low mass proportion (≈1%, w/w). The compression of the calibration powdered samples has been studied as a very simple procedure to enhance the sensitivity of NIR reflectance measurements and, consequently, to improve precision. Different pretreatments (SNV, 1D, 2D and their combinations) have been applied to reduce the spectral difference between powdered and compressed samples. Although none eliminates completely this difference, the combined pretreatment SNV+2D has proved to be the one with a better performance. Results obtained by using both calibration sample sets (powdered and compacted) in the quantification of estradiol valerate (VE, 2mg/tablet, ≈1.6%, w/w) and medroxyprogesterone (MPA, 10mg, ≈8%, w/w) in intact tablets of the hormonal preparation show that a slight but significant improvement in precision is obtained when using compacted samples for calibration. A HPLC procedure was developed to be used as reference method.

Superovulation and in vitro oocyte maturation in three species of mice (Mus musculus, Mus spretus and Mus spicilegus).

Mouse oocytes can be obtained via superovulation or using in vitro maturation although several factors, including genetic background, may affect response. Our previous studies have identified various mouse species as models to understand the role of sexual selection on the evolution of sperm traits and function. In order to do comparative studies of sperm-oocyte interaction, we sought reliable methods for oocyte superovulation and in vitro maturation in mature females of three mouse species (genus Mus). When 5 IU pregnant mare's serum gonadotrophin (PMSG) and 5 IU human chorionic gonadotrophin (hCG) were injected 48 h apart, and oocytes collected 14 h post-hCG, good responses were obtained in Mus musculus (18+/-1.3 oocytes/female; mean+/-S.E.M.) and Mus spretus (12+/-0.8), but no ovulation was seen in Mus spicilegus. Changes in PMSG or hCG doses, or longer post-hCG intervals, did not improve results. Use of PMSG/luteinizing hormone (LH) resulted in good responses in M. musculus (19+/-1.2) and M. spretus (12+/-1.1) but not in M. spicilegus (5+/-0.9) with ovulation not increasing with higher LH doses. Follicular puncture 48 h after PMSG followed by in vitro maturation led to a high oocyte yield in the three species (M. musculus, 23+/-0.9; M. spretus, 17+/-1.1; M. spicilegus, 10+/-0.9) with a consistently high maturation rates. In vitro fertilization of both superovulated and in vitro matured oocytes resulted in a high proportion of fertilization (range: 83-87%) in the three species. Thus, in vitro maturation led to high yields in all three species. These results will allow future studies on gamete interaction in these closely related species and the role of sexual selection in gamete compatibility.

Kinetic-spectrophotometric determination of theophylline, dyphylline, and proxyphylline by use of partial least-squares regression.

A kinetic-spectrophotometric method for the determination of theophylline, dyphylline and proxyphylline, based on their azo coupling reaction with the diazonium ion of sulfanilic acid after a treatment with alkali, is proposed. The absorbance is recorded from 340 to 600 nm every second during reaction for 90 s, and calibration is performed by partial least-squares regression, using first derivative spectra values. Mixtures containing 2.5-13 micro g mL(-1) dyphylline and proxyphylline, and 2-9 micro g mL(-1) theophylline were successfully resolved with root mean squared errors of prediction (RMSEP) of 0.4, 0.3, and 0.2 for dyphylline, proxyphylline, and theophylline, respectively. The proposed method was satisfactorily applied to the determination of the three compounds in a commercially available pharmaceutical preparation and provided results similar to those obtained by HPLC.

Influence of the procedure used to prepare the calibration sample set on the performance of near infrared spectroscopy in quantitative pharmaceutical analyses.

Calibrating near infrared diffuse reflectance spectroscopy (NIRS) methods usually involves preparing a set of samples with a view to expanding the analyte concentration range spanned by production samples. In this work, the performances of the two procedures most frequently used for this purpose in near infrared pharmaceutical analysis, viz., synthetic samples obtained by weighing of the pure constituents of the pharmaceutical and doped samples made by under- or overdosing previously powdered production samples, were compared. Both procedures were found to provide similar results in the quantification of the active compound in the pharmaceutical, which was determined with a relative standard error of prediction (RSEP) of < 1.6%. However, the two types of sample preparation provide different spectra, which precludes the accurate quantification of synthetic samples from calibrations obtained with doped samples and vice versa. None of the mathematical pre-treatments tested with a view to reducing this different scattering (viz., second derivative, standard normal variate and orthogonal signal correction) could effectively solve this problem. This hinders accurate validation of the linearity of the procedure and makes it advisable to use doped samples which are markedly less different to production samples.

Multi-component kinetic-spectrophotometric analysis. Selection of wavelength and time ranges.

An empirical method for the selection of the best wavelength and time ranges which can be used in the quantification of binary mixtures, in a kinetic-spectrophotometric system, is proposed. It is based on finding those ranges which provide the least correlation between the kinetic profiles and the spectra of the products of reaction. The method was applied to the analysis of binary mixtures using simulated data with different rate constant ratios and in the presence of an interference that shows spectral overlap with the analytes. Subsequently, the proposed method was applied to the resolution of dyphylline and proxyphylline mixtures. The system studied was characterized by an elevated similarity in the kinetic behavior of the analytes under pseudo-first-order conditions and an elevated degree of spectral overlap of the products of reaction. In spite of this, satisfactory results were obtained in the quantification of the two analytes. The standard error of prediction (SEP) and the standard deviation between replicates (SDBR) did not show significant differences, being of the order of 4 and of 3% for dyphylline and proxyphylline, respectively.

Resolution of isomers of sorbitolparaben esters by chromatographic and electrophoretic techniques.

Pharmaceutical preparations usually contain preservatives and sweeteners. When parabens are used as preservatives and a polyol as a sweetener, a transesterification reaction may happen, yielding the transester polyol-paraben. The products formed in the transesterification reaction of methylparaben and sorbitol were analyzed by micellar electrokinetic chromatography and by HPLC. Up to six positional isomers of sorbitolparaben (SPB) can be produced. However, only three peaks were found by HPLC. The higher efficiency and resolution power of MEKC allowed one to resolve five peaks. Results were compared with those obtained by capillary zone electrophoresis in borate buffer, where the separation of isomers occurred in a different way, because of a complexation between SPB and borate.

Analytical control of a pharmaceutical formulation of sodium picosulfate by capillary zone electrophoresis.

A new procedure for the analytical control of a pharmaceutical formulation by capillary zone electrophoresis (CZE) is proposed. It allows the simultaneous determination of the major compounds in the formulation: active compound (sodium picosulfate) and preservative (methylparaben), and the degradation products of the preservative, which slowly degrades by hydrolysis or by transesterification with sorbitol (sweetener in excess in the formulation) yielding p-hydroxybenzoic acid and sorbitolparaben, respectively. UV-Vis detection in the absorption maxima of the analytes and 20 mM borate solution at pH 10 as background electrolyte are used. Results are compared with those provided by the HPLC procedure. The method has also been validated using the HPLC procedure as the reference method, evaluating selectivity, accuracy, linearity and precision. The CZE procedure developed is sufficiently accurate and the precision achieved is about 1% for major and 3% for minor compounds.

The role of abscisic acid in controlling leaf water loss, survival and growth of micropropagated Tagetes erecta plants when transferred directly to the field.

Plants of Tagetes erecta L. (marigold) cultivated in vitro in ventilated containers exhibited greater control of leaf water loss and increased survival in the field than plants cultivated in sealed containers. Increased field survival of plants cultivated in ventilated containers was attributed to higher levels of endogenous abscisic acid (ABA). Therefore, ABA was supplied exogenously to plants in sealed or ventilated containers by adding ABA (10(-6), 10(-5), 10(-4) M) to the in vitro culture media in order to evaluate control of leaf water loss, growth and field survival. The addition of 10(-4) M ABA to the culture media in sealed containers produced plants that had similar control of leaf water loss and were morphologically similar to plants cultivated in ventilated containers without the addition of ABA. Field survival of 10(-4) M ABA plants (75%) was increased compared to plants cultivated in sealed containers without ABA (31%), with survival being closer to that of plants cultivated in ventilated containers (90-100%). Plants cultivated with 10(-4) M ABA (sealed and ventilated) also exhibited increased plant vigour and leaf area in the field compared to plants cultivated without ABA. The results suggest that the limited field survival and growth of plants cultured in vitro are related to the limited ABA concentrations they accumulate while in vitro. Consequently, conditions that increase the endogenous ABA concentrations of in vitro plants (like ventilation or ABA addition to the medium) would improve the control of leaf water loss, field survival and plant vigour.

Fundoplicatura de Nissen laparoscópica versus convencional / Nissen's laparoscopic fundoplication versus conventional

La fundoplicatura de Nissen laparoscópica (FPNL) debe igualar los resultados inmediatos de la fundoplicatura de Nissen convencional (FPNC) para conseguir su aceptación en el ambiente quirúrgico nacional. El objetivo de esta publicación es comparar los índices de morbimortalidad de la FPN hecha con los accesos mencionados. Se compara un grupo de 53 FPNL de un total 70 pacientes operados desde 1993, con 77 FPNC elegidos aleatoriamente de 250 pacientes operados desde 1976. En ambos grupos se incluyeron pacientes con RGEP y esofagitis de reflujo, c/s Barret no complicado, c/s hernia hiatal axial (HH) pequeña y c/s colelitiasis asociada, descartando las HH medianas, grandes y paraesofágicas y los Barret complicados y los asociados a enfermedad ulcerosa gastroduodenal. Todos los pacientes de ambos grupos tenían RGEP y esofagitis de reflujo demostrada con fracaso del tratamiento médico; asociado a Barret en 16 pacientes (30,1 por ciento), a HH en 5 pacientes (9,4 por ciento) y a colelitiasis en 29 pacientes (54,7 por ciento) en la FPNL, y a Barret en 6 pacientes (7,8 por ciento), a HH axial en 9 pacientes (11,7 por ciento y a colelitiasis en 50 pacientes (64,9 por ciento) en la FPNC. A todos se les practicó una operación de Nissen de 180º, agregándose una colecistectomía en 50 casos de FPNC y en 29 casos de FPNL. En el caso de cirugía laparoscópica se convirtieron 2 pacientes (3,8 por ciento). Observamos una morbilidad del 1,3 por ciento en cirugía abierta, y del 5,7 por ciento en la cirugía laparoscópica. No hubo mortalidad

Development and validation of a near infrared method for the analytical control of a pharmaceutical preparation in three steps of the manufacturing process.

A near infrared diffuse reflectance spectroscopy (NIRS) procedure for the quantitative control analysis of the active compound (otilonium bromide) in a pharmaceutical preparation in three steps of the production process (blended product, cores and coated tablets) and a methodology for its validation are proposed. The analytical procedure is composed by two consecutive steps. First, the sample is identified by comparing its spectrum with a second derivative spectral library. If the sample is positively identified, the active compound is quantified by using a previously established partial least squares (PLS) calibration model. The procedure was validated by studying repeatability, intermediate precision, accuracy and linearity. To this end, an adaptation of ICH (International Conference on Harmonisation) validation methodology to an NIR multivariate calibration procedure is proposed. The relative standard error of prediction (RSEP) was < or = 1% and the suitability of the procedure for control analysis was confirmed by the results obtained analysing new production samples produced over a three-month period.

Simultaneous kinetic-spectrophotometric determination of levodopa and benserazide by bi- and three-way partial least squares calibration.

A procedure for the simultaneous kinetic-spectrophotometric determination of levodopa (I) and benserazide (II), from their oxidation reaction with KIO(4) in an acidic medium, is described. Both species instantly oxidize, giving rise to compounds which present maximum values of absorbance close to 400 nm. In the presence of an excess of the oxidizing agent, the levodopa derivative evolves to form the corresponding aminochrome (lambda(m)=480 nm), while the benserazide derivative decomposes to yield colorless compounds. The appearance of new compounds, with absorption bands in the region of 500-700 nm, is additionally seen upon adding the oxidizing agent to a mixture of I and II. These compounds also evolve decomposing and forming colorless products. In spite of the complexity of the system studied, the calibration by bi-linear partial least squares (PLS) as well as by three-way partial least squares (nPLS) permit the quantification of both analytes with a precision on the order of 0.7% for levodopa and of 1.5% for benserazide. nPLS also allows for the qualitative interpretation of the phenomena which occur. The proposed method is applied to the quantification of I and II in the commercial, pharmaceutical preparation Madopar, using high performance liquid chromatography (HPLC) as the analytical reference technique.

Development and validation of a method for the analysis of a pharmaceutical preparation by near-infrared diffuse reflectance spectroscopy.

A near-infrared (NIR) spectroscopic method based on the use of a fiber optical probe for the analysis of a commercially available pharmaceutical preparation is proposed. The analyte is identified by comparison with a second-derivative spectral library, using the correlation coefficient as the discriminating parameter. Once a sample has been positively identified, the active principle is quantified with partial least-squares (PLS) calibration. The proposed method was validated for use as a control method; to this end, the selectivity of the identification process, and the repeatability, intermediate precision, accuracy, linearity, and robustness of the active principle quantitation, were assessed.

Tuberculous pleural effusion in children.

STUDY OBJECTIVES: To describe the age distribution, clinical, laboratory, radiographic, and bacteriologic findings of pediatric patients with tuberculous pleural effusion. DESIGN: A retrospective study. PATIENTS AND METHODS: We have identified all cases of primary pulmonary tuberculosis in children < 18 years, reported to the health department. We have collected information from medical records regarding demographics, clinical findings, bacteriologic results, and evolution. Chest radiographs obtained at the time of initial evaluation were reviewed independently by two groups of radiologists who were blind to the clinical and epidemiologic data. RESULTS: Between January 1983 and December 1996, 175 children < 18 years were diagnosed as having primary pulmonary tuberculosis. Among them, 39 patients (22.1%) showed pleural effusion on chest radiograph. The mean age of patients with tuberculous pleural effusion was significantly higher (13.52+/-0.5 years vs 6.97+/-0.42 years). The sensitivity of the tuberculin test is 97.4% for an induration > or = 5 mm. Pleural fluid analysis shows a lymphocytic exudative effusion. Chest radiograph review showed unilateral pleural effusion in all cases. Pleural effusion was the sole radiographic manifestation in 41% of cases. Parenchymal disease is associated in 23 cases (59%). Bacteriologic confirmation of tuberculosis was achieved in 22 cases (56.4%). Cultures of pleural fluid and biopsy material both yielded Mycobacterium tuberculosis in 15 of 34 (44.1%) and 12 of 18 (66.6%), respectively, for samples under study. Pleural biopsy specimens showed granulomatous inflammation in 18 of 23 cases (78.3%). Antituberculous therapy for 6 to 9 months was effective in all cases. Transient side effects occurred in 1 of 39 patients (2.9%). CONCLUSIONS: Pleural effusion accounts for 22.1% of cases of pediatric pulmonary tuberculosis. Parenchymal consolidation is the most common associated radiographic finding. Bacteriologic confirmation was achieved in 56.4% of cases. A short course of chemotherapy is effective.

Development and validation of methods for the determination of miokamycin in various pharmaceutical preparations by use of near infrared reflectance spectroscopy.

New methods for the determination of the nominal content of miokamycin in three commercial pharmaceutical preparations available in many different forms are proposed. Solid samples, grinding of which is the sole pretreatment required, are analysed by near infrared (NIR) spectroscopy, using a fibre-optic probe. The active principle is quantified by partial least-squares regression (PLSR). The three proposed methods were validated with a view to their use as control methods; the selectivity of the method, and the repeatability, intermediate precision, accuracy, linearity and robustness of each PLSR calibration model used were determined. The relative standard error of prediction (RSEP) was < 1.5% and the validation results testify to the suitability of the proposed methods.

Kinetic spectrophotometric determination of hydrocortisone acetate in a pharmaceutical preparation by use of partial least-squares regression.

A kinetic spectrophotometric method for the determination of hydrocortisone acetate based on its condensation with isonicotinic acid hydrazide is proposed. The method is applied to the determination of hydrocortisone acetate in a commercially available pharmaceutical preparation, presented as a pomade, that also contains another corticosteroid and additional active compounds. The operating procedure involves dissolving the pomade in chloroform and the addition of the reagent solution directly to the cuvette, in this way avoiding the previous extraction of analytes from the insoluble pomade matrix required by the alternative HPLC procedure. Calibration is performed by partial least-squares regression, using absorbance or first derivative spectra values recorded each minute during the first 30 min of reaction. Use of first derivative spectra overcomes possible scattered light problems produced by excipients precipitating, and produced slightly better results than absorbance data. The relative standard deviation obtained for 11 replicates analysed on different days was approx. 1.5%. The proposed method improves both accuracy and precision of the classical initial rate method and the precision of the HPLC procedure.

Isozymatic variation and phylogenetic relationships between henequen (Agave fourcroydes) and its wild ancestor A. angustifolia (Agavaceae).

Isozymatic variation and phylogenetic relationships among extant henequén (Agave fourcroydes) germplasm and wild populations of its ancestor A. angustifolia in the Yucatan Peninsula in Mexico were analyzed. Analysis of three isozyme systems using starch gel electrophoresis indicated that while A. angustifolia populations have relatively high levels of variation, within each henequén cultivar all individuals were identical. This result corresponds to previous ethnobotanical and morphological analyses, which indicated severe loss of genetic variation of this domesticated plant as a consequence of the promotion by means of asexual propagation of only one cultivar since the middle of the last century. The three extant cultivars of henequén were distinct from each other. Two of them, Sac Ki (SK) and Yaax Ki (YK), could be matched within the progenitor, but Kitam Ki (KK) has a MDH electrophenotype not found in any of the plants growing inside the Yucatan Peninsula, but found in some A. angustifolia plants growing in the Mexican states of Oaxaca and Veracruz. A parsimony analysis of the morphological data indicated two lineages: that of SK and YK, cultivated cordage plants selected for stronger and longer fibers, whose sister group is the Tropical subdeciduous forest ecotype (SF), and that of all the other wild populations, which also included KK, the cultivated textile plants selected for finer fibers and nearly extinct in Yucatan. These results support the hypothesis of the yucatecan origin of SK and YK from the SF ecotype, as well as the hypothesis of a recent introduction of KK to the Yucatan Peninsula in a domestication trend that probably included also Chelem White (its cultivation being abandoned later).