Transvaginal sonographic features of diffuse adenomyosis in 18-30-year-old nulligravid women without endometriosis: association with symptoms.

OBJECTIVES: To investigate whether there are sonographic features of diffuse adenomyosis in 18-30-year-old nulligravid women without endometriosis and to examine their association with symptoms of dysmenorrhea and abnormal uterine bleeding. METHODS: This was a prospective observational study including women referred from a gynecology outpatient center to our university hospital for ultrasound examination. Inclusion criteria were age between 18 and 30 years, regular menstrual cycle and nulligravid status. Exclusion criteria were a past or current history of endometriosis, fibroids, ovarian cysts or lesions, endometrial pathology, current use of hormonal treatments or medications that would affect the menstrual cycle, previous uterine surgery and history of infertility. Women underwent a detailed clinical assessment and a two- (2D) and three-dimensional (3D) transvaginal ultrasound (TVS) examination. 2D-TVS features associated with diffuse adenomyosis were predefined as: (1) heterogeneous myometrium; (2) hypoechoic striation in the myometrium; (3) myometrial anechoic lacunae or cysts; (4) asymmetrical myometrial thickening of the uterine walls with the presence of straight vessels, extending into the hypertrophic myometrium, on power Doppler examination. On 3D-TVS, endomyometrial junctional zone (JZ) was measured as the distance from the basal endometrium to the internal layer of the outer myometrium on coronal section at any level of the uterus, and the smallest (JZmin) and largest (JZmax) JZ thicknesses and their difference (JZdiff) were recorded. 3D-TVS evaluation was considered suggestive for adenomyosis when JZmax ≥ 8 mm and/or JZdiff ≥ 4 mm. The presence of associated symptomatology represented our main outcome: the amount of menstrual loss was assessed by a pictorial blood loss analysis chart (PBAC) and painful symptoms were evaluated using a visual analog scale (VAS). RESULTS: During the observation period, 205 women (median age, 24 (interquartile range, 23-27) years) were enrolled into the study and 156 met the inclusion criteria. According to the 2D-TVS criteria, diffuse adenomyosis was found in 53 (34.0%) women and asymmetrical myometrial thickening of the uterine walls was the most common sonographic feature observed. ANOVA showed a significant relationship between the number of 2D-TVS features of diffuse adenomyosis and VAS score for dysmenorrhea (P = 0.005) as well as PBAC score for menstrual loss (P = 0.03). 3D-TVS showed that women with 2D-TVS features of diffuse adenomyosis had a significantly higher value of JZmax (6.38 ± 2.30 mm, P < 0.001), JZmin (2.07 ± 0.43 mm, P = 0.002) and JZdiff (4.33 ± 1.99 mm, P < 0.001) than did women without these features. Women with sonographic features of diffuse adenomyosis were symptomatic in 83% of cases, reported dysmenorrhea in 79.2% and showed a higher incidence of heavy bleeding than did those without these features (18.9% vs 2.9%; P = 0.001). CONCLUSIONS: Sonographic features suggestive of diffuse adenomyosis may develop earlier in reproductive life than previously thought, and may occur in association with dysmenorrhea and abnormal uterine bleeding in nulligravid women. Their observation in these women should therefore warrant further gynecological investigation.

Response surface methodology in the optimization of chitosan-Ca pectinate bead formulations.

This study describes the application of a multi-varied experimental design methodology to the optimization of a bead formulation based on a mixed network of Ca pectinate and chitosan. The effect of varying the relative percent of the three components used for the bead production, i.e. pectin, chitosan and CaCl(2), has been systematically investigated with the aim of identifying their best levels to optimize drug encapsulation efficiency (considered as the experimental response to be maximized), as well as to highlight possible interactions among the components. The study was applied to two different drugs, i.e. prednisone and theophylline, selected, respectively, as model insoluble and relatively soluble drugs, in order to evaluate the influence of this parameter as well. Different bead batches were prepared according to Doehlert and D-optimal design and randomly evaluated for drug encapsulation efficiency. Analysis of response surface plots allowed identification of the best combination of the three bead components in order to maximize drug encapsulation efficiency. The most effective compositions were chitosan 3% (w/v), pectin 9% (w/v), CaCl(2) 4% (w/v) for the theophylline-loaded beads and chitosan 0.75% (w/v), pectin 6% (w/v), CaCl(2) 7.9% (w/v) for the prednisone-loaded ones. The good correspondence between calculated and experimental values indicated in both cases the validity of the generated statistical models for the prediction of microsphere encapsulation efficiency. The different results obtained for the two drugs indicated the importance of the greater or lesser drug lipophilicity in determining the optimal bead composition with the highest encapsulation efficiency.

Enantioseparation and impurity determination of ambrisentan using cyclodextrin-modified micellar electrokinetic chromatography: Visualizing the design space within quality by design framework.

A capillary electrophoresis method for the simultaneous determination of the enantiomeric purity and of impurities of the chiral drug ambrisentan has been developed following the Quality by Design principles. The selected separation system consisted of a micellar pseudostationary phase made by sodium dodecyl sulphate with the addition of γ-cyclodextrin. The effects of critical process parameters (capillary length, temperature, voltage, borate concentration, pH, sodium dodecyl sulphate concentration, γ-cyclodextrin concentration) on enantioresolution of ambrisentan and analysis time were extensively investigated by multivariate strategies involving a screening phase and Response Surface Methodology. The Design Space was defined with a desired probability level π≥90%, and the working conditions, with the limits of the Design Space, corresponded to the following: capillary length, 64.5cm; temperature, 22°C; voltage, 30kV (26-30kV); background electrolyte, 100mM borate buffer pH 9.20 (8.80-9.60), 100mM sodium dodecyl sulphate, 50mM (43-50mM) γ-cyclodextrin. A Plackett-Burman design was applied for robustness testing, and a method control strategy was established. The method was fully validated according to the International Conference on Harmonisation guidelines and was applied to ambrisentan coated tablets.

Optimization of glibenclamide tablet composition through the combined use of differential scanning calorimetry and D-optimal mixture experimental design.

A systematic analysis of the influence of different proportions of excipients on the stability of a solid dosage form was carried out. In particular, a d-optimal mixture experimental design was applied for the evaluation of glibenclamide compatibility in tablet formulations, consisting of four classic excipients (natrosol as binding agent, stearic acid as lubricant, sorbitol as diluent and cross-linked polyvinylpyrrolidone as disintegrant). The goal was to find the mixture component proportions which correspond to the optimal drug melting parameters, i.e. its maximum stability, using differential scanning calorimetry (DSC) to quickly obtain information about possible interactions among the formulation components. The absolute value of the difference between the melting peak temperature of pure drug endotherm and that in each analysed mixture and the absolute value of the difference between the enthalpy of the pure glibenclamide melting peak and that of its melting peak in the different analyzed mixtures, were chosen as indexes of the drug-excipient interaction degree.

Interaction of naproxen with ionic cyclodextrins in aqueous solution and in the solid state.

The possible role of the cyclodextrin charge in the interaction with an acidic drug such as naproxen (pKa 4.8) has been evaluated. Sulfobutylether-beta-cyclodextrin (SBE-betaCyd) and trimethylammonium-beta-cyclodextrin (TMA-betaCyd) were selected as, respectively, anionically and cationically charged carriers and their performance was compared with that of the parent beta-cyclodextrin (betaCyd) and of its methyl-derivative (Me betaCyd) previously found as the best partner for the drug. Interactions in solution were investigated by phase-solubility, fluorescence and circular dichroism analyses. Equimolar drug-carrier products prepared by different techniques (blending, cogrinding, sealed-heating, colyophilization) were characterized by differential scanning calorimetry and X-ray powder diffractometry and tested for drug dissolution properties. Anionic charges of SBE-betaCyd did not negatively influence interactions in unbuffered aqueous solutions (pH approximately 5) with the acidic drug. In fact, it was a very effective carrier, exhibiting solubilizing and complexing properties considerably better than the parent betaCyd and comparable to those of Me betaCyd. On the contrary, the positive charges of TMA-betaCyd did not favour interactions with the counter-ionic drug (despite the presence of about 60% ionised drug) and it was less efficacious also than native betaCyd. Therefore, the role of the Cyd charge on the complexing and solubilizing properties towards naproxen was not important whereas other factors, such as steric hindrance effects and favourable hydrophobic interactions were significant in determining the drug affinity for the Cyd inclusion. Solid state studies evidenced similar amorphizing properties of both charged Cyds towards naproxen. On the other hand, dissolution tests, in agreement with solution studies, showed that all products with SBE-betaCyd exhibited significantly better dissolution properties than the corresponding ones with TMA-betaCyd. A clear influence of the preparation method of drug-Cyd solid systems on the performance of the end product was also observed. Colyophilization was the most effective technique, followed by the cogrinding one. Colyophilized product with SBE-betaCyd allowed a 10-times increase in drug dissolution efficiency (D.E.) (with respect to the five-times increase obtained with the corresponding coground product) and a reduction of t(50%) from about 60 min (for the coground product) to less than 2 min.

Determination of stability constant values of flurbiprofen-cyclodextrin complexes using different techniques.

Three new experimental approaches for calculating the stability constant (K(st)) of complexes of flurbiprofen with natural beta-cyclodextrin (betaCyd) and the hydroxyethyl- (HEbetaCyd) and the methyl- (Me betaCyd) derivatives were tested and compared to the classic phase-solubility procedure: (a) the membrane permeation technique through a lipophilic synthetic membrane permeable to the drug but not to the Cyd molecules, by analysing the permeation profiles with a non-linear least-squares method; (b) the affinity capillary electrophoresis (ACE) technique, where K(st) were calculated from the relationship between Cyd concentration in solution and drug electrophoretic mobility, using three different linear plotting methods; (c) the molecular modeling technique, based on the relationship between the docking energies and the experimental K(st) values. The study allowed evaluation of the advantages and limits of each examined method, providing a useful guide for the choice of the most suitable one depending on the kind of host-guest system to be investigated. The K(st) values obtained with the various techniques were rather different, probably due to the very different experimental conditions required by each one. However, all the methods indicated the methyl-derivative as the most powerful complexing agent for the drug, showing the general trend: K(st)(Me betaCyd)>>K(st)(HEbetaCyd)>K(st)(betaCyd). Only in the case of the ACE method was an inversion of the trend found between HEbetaCyd and betaCyd; this was probably due to the lower molecular weight of the natural Cyd, which, in this case, became more important in determining the complex electrophoretic mobility than the different affinity of the drug for these two Cyds.

Quality by design in the chiral separation strategy for the determination of enantiomeric impurities: development of a capillary electrophoresis method based on dual cyclodextrin systems for the analysis of levosulpiride.

Quality by design (QbD) concepts, in accordance with International Conference on Harmonisation Pharmaceutical Development guideline Q8(R2), represent an innovative strategy for the development of analytical methods. In this paper QbD principles have been comprehensively applied in the set-up of a capillary electrophoresis method aimed to quantify enantiomeric impurities. The test compound was the chiral drug substance levosulpiride (S-SUL) and the developed method was intended to be used for routine analysis of the pharmaceutical product. The target of analytical QbD approach is to establish a design space (DS) of critical process parameters (CPPs) where the critical quality attributes (CQAs) of the method have been assured to fulfil the desired requirements with a selected probability. QbD can improve the understanding of the enantioseparation process, including both the electrophoretic behavior of enantiomers and their separation, therefore enabling its control. The CQAs were represented by enantioresolution and analysis time. The scouting phase made it possible to select a separation system made by sulfated-ß-cyclodextrin and a neutral cyclodextrin, operating in reverse polarity mode. The type of neutral cyclodextrin was included among other CPPs, both instrumental and related to background electrolyte composition, which were evaluated in a screening phase by an asymmetric screening matrix. Response surface methodology was carried out by a Doehlert design and allowed the contour plots to be drawn, highlighting significant interactions between some of the CPPs. DS was defined by applying Monte-Carlo simulations, and corresponded to the following intervals: sulfated-ß-cyclodextrin concentration, 9-12 mM; methyl-ß-cyclodextrin concentration, 29-38 mM; Britton-Robinson buffer pH, 3.24-3.50; voltage, 12-14 kV. Robustness of the method was examined by a Plackett-Burman matrix and the obtained results, together with system repeatability data, led to define a method control strategy. The method was validated and was finally applied to determine the enantiomeric purity of S-SUL in pharmaceutical dosage forms.

Micellar electrokinetic chromatography for the simultaneous determination of ketorolac tromethamine and its impurities. Multivariate optimization and validation.

A simple, fast and selective micellar electrokinetic chromatographic (MEKC) method for the simultaneous assay of ketorolac tromethamine and its known related impurities (1-hydroxy analog of ketorolac, 1-keto analog of ketorolac and decarboxylated ketorolac), in both drug substance and coated tablets, is described. The compounds were detected at 323 nm, and flufenamic acid (FL) and tolmetin (TL) were chosen as internal standards to quantify ketorolac tromethamine and impurities, respectively. The multivariate optimization of the experimental conditions was carried out by means of the response surface study, considering as responses the resolution values and analysis time. The optimized background electrolyte (BGE) consisted of a mixture of 13 mM boric acid and phosphoric acid, adjusted to pH 9.1 with 1 M sodium hydroxide, containing 73 mM sodium dodecyl sulfate (SDS). Optimal temperature and voltage were 30 degrees C and 27 kV. Applying these conditions, all compounds were resolved in about 6 min. The related substances could be quantified up to the 0.1% (w/w) level. Validation was performed, either for drug substances and drug product, evaluating selectivity, robustness, linearity and range, precision, accuracy, detection and quantitation limits and system suitability.

Design of experiments for capillary electrophoretic enantioresolution of salbutamol using dermatan sulfate.

Statistical experimental design was used for the optimization and for robustness evaluation of a capillary electrophoretic method developed for the enantioresolution of salbutamol. Dermatan sulfate was used as chiral selector. The goal of the study was to obtain an efficient and fast separation. An eight-run Plackett-Burman matrix was used during the optimization process for the screening of the factors and to adjust the experimental domain under study. Response surface methodology was adopted after the screening phase to obtain information about how the factors percentage of chiral selector, pH and voltage affected the considered responses resolution and analysis time. The Derringer desirability function, which makes it possible to combine results obtained for properties measured on different scales, was used to simultaneously optimize the two responses. Robustness testing was carried out using a Plackett-Burman matrix. The method was found robust as regards the response resolution while voltage and chiral selector were found to be critical factors for the robustness of analysis time response. The proposed CE method permitted the complete enantioseparation of racemic salbutamol and was applied to its chiral resolution in spiked urine samples.

Improving gas chromatographic determination of residual solvents in pharmaceuticals by the combined use of headspace solid-phase microextraction and isotopic dilution.

Cyclohexane and toluene were gas chromatographically determined via headspace solid-phase microextraction both in ketoprofen drug substance and ketoprofen capsules by a procedure relying on isotopic dilution (ID), an analytical tool derived from mass spectrometry (MS). This approach, using an internal standard method, gave mean precision and accuracy (RSD 2.56%, 2.97% and bias 0.21%, -0.99% for cyclohexane and toluene, respectively) not obtainable by the more commonly used external standard ones in the presence of real sample matrices. Optimisation of the operative conditions was also supported by experimental design. More generally, the proposed method, exploiting ID without resort to the costly MS instrumentation, could be recommended whenever opportune deuterated analogues of the target analytes and GC capillary columns able to separate all the peaks involved are ready available on the market.

Gravimetric determination of chlorhexidine using tetraphenylborate ion.

A precise and accurate gravimetric procedure was developed for the determination of chlorhexidine diacetate, digluconate, or dihydrochloride. Sodium tetraphenylborate solution was the precipitant in an acidic medium (pH 1). Tablets containing both chlorhexidine diacetate and benzocaine also were assayed.

Influence of the preparation method on the physicochemical properties of ketoprofen-cyclodextrin binary systems.

Binary systems of ketoprofen with native crystalline beta-cyclodextrin and amorphous statistically substituted methyl-beta-cyclodextrin were investigated for both solid phase characterization (Differential Scanning Calorimetry, powder X-ray diffraction, Infrared Spectroscopy, Scanning Electron Microscopy) and dissolution properties (dispersed amount and rotating disc methods). Grinding, kneading, sealed-heating and colyophilization of equimolar combinations of ketoprofen with methyl-beta-cyclodextrin, as well as colyophilization of analogous combinations with beta-cyclodextrin, led to amorphous products. Crystalline drug, instead, was still clearly detectable in coground, kneaded and sealed-heated products with beta-cyclodextrin. Both the preparation method, and even more the nature of the carrier, played an important role in the performance of the system. Colyophilized and sealed-heated products showed the best dissolution properties. However, independently of the preparation technique, all combinations with methyl-beta-cyclodextrin yield better performances than the corresponding ones with the beta-cyclodextrin. Moreover, intrinsic dissolution rate of ketoprofen from simple physical mixture with the beta-cyclodextrin derivative was even five-fold higher than that from the best product with the parent beta-cyclodextrin.

Potentiometric titration of thiols, cationic surfactants and halides using a solid-state silver-silver sulphide electrode.

A rugged, low resistance silver-silver sulphide solid-state electrode for determining pharmaceuticals as authentic samples or in dosage forms by potentiometric titration is described. Sodium tetraphenylborate, mercury(II) acetate and silver nitrate (0.01) M were employed as titrants in the analysis of cationic surfactants (cetylpyridinium chloride, benzethonium chloride, benzalkonium chloride and chlorhexidine salts), antithyroid drugs (methimazole and propylthiouracil) or sodium halides respectively.

Optimization and validation of a CZE method for rufloxacin hydrochloride determination in coated tablets.

A simple and rapid capillary electrophoresis method with UV detection was developed and validated for the determination of rufloxacin hydrochloride in coated tablets. An experimental design strategy (Doehlert design and desirability function) allowed the analytical parameters to be simultaneously optimized in order to determine rufloxacin hydrochloride with high peak area/migration time ratio, good efficiency and short analysis time. Optimized analyses were run using boric acid 0.10 M adjusted to pH 8.8 as BGE and setting voltage and temperature at 18 kV and 27 degrees C, respectively. Pefloxacin mesylate was used as internal standard and run time was about three minutes. The method was validated for the drug substance and the drug product according to the ICH3 guidelines. Robustness was tested by experimental design using an eight-run Plackett-Burman matrix.

Experimental design strategies in the optimization and robustness testing of adsorptive stripping voltammetric conditions for kynurenic acid determination.

Experimental design was used for the optimization and robustness testing of an adsorptive stripping voltammetric procedure for kynurenic acid determination. The optimization of the peak height response proceeded through a screening phase (D-optimal design strategy) followed by a response surface study (Doehlert design) applied to the variables pH, pulse amplitude and stirring rate. An interaction between pH and stirring rate was pointed out. The optimized method was validated and the variation of factors that was expected to occur in practice was simulated in a robustness test. A composite fractional matrix for the evaluation of method robustness was used and pH emerged as the only critical factor. The linear range found applying the optimized conditions was 2.5 x 10(-9) to 2.5 x 10(-7) M and the calculated limit of detection was 1.72 x 10(-9) M.

Set-up and validation of an adsorptive stripping voltammetric method for kynurenic acid determination in human urine.

Validation of an adsorptive stripping voltammetric method for kynurenic acid determination in urine, was presented. The selection of appropriate validation parameters, the design consideration for evaluation and the problem of endogenous metabolites were discussed. The considered fundamental criteria for assessing the reliability and overall performance of the method in the urine matrix were selectivity, linearity and range, limit of quantitation, accuracy, precision and analyte stability. The intermediate precision was also evaluated by means of a full factorial design. An HPLC method with fluorimetric detection was used as a reference method to assess the accuracy. The analysis in urine required a pH control as pointed out by robustness testing and the found kynurenic acid concentration in daily urine ranged from 5 to 40 microM.

Optimization of dissolution test precision for a ketoprofen oral extended-release product.

An example of application of experimental design methodologies to the set up of dissolution test conditions for a new ketoprofen oral extended-release dosage form is presented. The aim of the work was to find the best experimental conditions, using a USP apparatus 2 (paddle), for maximizing the method precision as degree of repeatability. The considered factors mainly influencing the dissolution test results were pH and volume of dissolution medium, and paddle stirring speed. Two distinct 4-run Plackett-Burman designs were carried out: one at gastric and the other at intestinal pH values. Each run was performed in triplicate in order to calculate the standard deviations of the drug dissolution efficiency at 60 and 120 min, selected as responses to be minimized. Optimum conditions to carry out the dissolution test were: 900 ml volume of dissolution medium and 70 rpm paddle stirring speed for both environments and pH 1 and 5.5, for the gastric and intestinal environment, respectively.

Characterization of physicochemical properties of naproxen systems with amorphous beta-cyclodextrin-epichlorohydrin polymers.

Ground mixtures of naproxen with amorphous beta-cyclodextrin-epichlorohydrin soluble (betaCd-EPS) or insoluble cross-linked (betaCd-EPI) polymers were investigated for both solid phase characterization (Differential Scanning Calorimetry, powder X-ray Diffractometry) and dissolution properties (dispersed amount method). The effect of different grinding conditions and of drug-to-carrier ratio was also evaluated. Co-grinding induced a decrease in drug crystallinity to an extent which depended on the grinding time, and was most pronounced for the cross-linked insoluble polymer, particularly in combinations at the lowest drug content. Both cyclodextrin polymers were more effective in improving the naproxen dissolution properties, not only than the parent betaCd but also than hydroxyalkyl-derivatives, and their performance was almost comparable to that of methyl-derivatives, previously found as the best carriers for naproxen. Dissolution efficiencies of naproxen from physical mixtures with betaCd-EPS, thanks to the high water solubility of this Cd-derivative, were up to three times higher than those from the corresponding products with betaCd-EPI. However this difference in their performance became much less evident in co-ground products and tended to progressively diminish with increasing the polymer content in the mixture, according to the better amorphizing power shown by betaCd-EPI during the co-grinding process. The 10/90 (w/w) drug-carrier co-ground products exhibited the best dissolution properties, giving dissolution efficiencies about 30 times higher than that of naproxen alone.

Design and optimization of the variables in the adsorptive stripping voltammetric determination of rufloxacin in tablets, human plasma and urine.

An adsorptive stripping voltammetric method with a hanging mercury drop electrode was developed for the determination of the fluoroquinolone rufloxacin in tablets, human plasma and urine. Measurements were obtained in differential pulse mode and a multivariate strategy was used to optimize the variables involved. Besides the independent effects of the variables, a strong interaction between scan rate and pulse duration has been found. Rufloxacin was analysed at concentrations between 1.7 x 10(-8) and 1.9 x 10(-7) M with a detection limit of 9.2 x 10(-9) M. Diluted tablet solutions and urine samples were analysed directly, while plasma samples needed an extraction procedure before voltammetric analysis. An improved HPLC procedure was used as comparative method.

Experimental design in the development of voltammetric method for the assay of omeprazole.

A multivariate strategy was used to optimize an adsorptive stripping voltammetric method for the determination of the antiulcer drug omeprazole. A 3/4 matrix was used for the variable screening while a central composite design was chosen in the subsequent step to evaluate the response surfaces. Simultaneous optimization of the response peak height (hp) and peak half width w1/2), the latter being a peak shape measure, was achieved. The factors accumulation time, pulse amplitude, scan rate and stirring rate were all found to be statistically significant for the response hp, while for the response w1/2 only the stirring rate was found to be significant. The optimized method shows a good linearity between peak height and analyte concentration in the concentration range from 8.33 x 10(-9) M to 1.42 x 10(-7) M with a LOD of 6.5 x 10(-9) M. The mean recovery of omeprazole in capsules was 101.9% with a SD of 2.04 (RSD = 200).