Internal Structure Quality Control of Solid Pharmaceuticals. A Comparative Study

Objective: The aim of the study was a comparative investigation by spectral and thermal analysis in order to asses a number of characteristics of different varieties ofrawmaterials of ursodeoxycholic acid and ibuprofen. The different dissolution behavior of two ursodeoxycholic acid pharmaceutical product by crystallinity pattern was investigated. Methods: Raw materials of ursodeoxycholic acid and ibuprofen were used. IR spectroscopy, differential scanning calorimetry and X-Ray Diffraction Analysis were applied. Results: The results show no crystallinitydifferences for different batches of the tested drugs. No solid solid transition was proved during sample preparation for transmission IR analysis. Conclusions: A combination of two more affordabletests by IR spectrometry and differential scanning calorimetry lead to the same results as X-Ray diffraction analysis for crystallinity similarity assessment of the studied substances. The dissolution differences of test drugs were not related to the polymorphism of the raw materials.

Heterocycles 21. Reaction of 2-phenyl-thiazol-4-carbaldehyde with 2-bromoacetophenone

The condensation reaction of 2-phenyl-thiazol-4-carbaldehyde with 2-bromoacetophenone was performed in basic catalysis, resulting in a mixture of 2,3-epoxy-1-phenyl-3-(2-phenyl-thiazol-4-yl)-propan-1-one (1), 1-phenyl-3-(2-phenyl-thiazol-4-yl)-propane-1,2-dione (2) and 2-phenyl-4,5-bis-(2-phenyl-thiazol-4-yl)-3-hydroxy-furane (4). The isolated solids were structurally investigated by spectroscopic methods, i.e. infrared spectroscopy, mass spectrometry and NMR. In solution the dicarbonylic derivative 2 undergoes a tautomeric process, resulting in the enol 2-hydroxy-1-phenyl-3-(2-phenyl-thiazol-4-yl)-prop-2-en-1-one 3. Compounds 3 and 4 were transformed in the corresponding acetyl derivatives 5 and 6, respectively, by reacting them with acetic anhydride. For the furane 4 the single crystal X-ray diffraction structure was determined.

The Influence of Some Factors on Spirolactone Stability in Solution

The influence of some factors on spironolactone stability in solution was studied, by applying high-performance liquid chromatography, as a part of a pharmaceutical preformulation study in order to obtain a spironolactone solution for alopecia treatment. Solutions of 1 mg/ml spironolactone in aqueous ethanolic solution 1 : 1 and in 20 mM cyclodextrines solutions (b-, hydroxi-b- and methyl-b-cyclodextrine) was used, maintained at 8 and 22 �C, protected from light and after UV irradiation at 254 nm. The main degradation products were 7a-thiospirolactone and canrenone. The most stable solutions were the alcoholic ones and with methyl-beta-cyclodextrine, but the simultaneous action of temperature and UV irradiation allowed degradation processes after one hour of exposure, more aggressive in the presence of methyl-beta-cyclodextrine. In conclusion, for alopecia treatment with spironolactone a 1 mg/mL ethanolic solution could be used and it is recommendable the protection of treated zone.

[Stability of some medicinal solutions with captopril]

The aim of the study was to investigate the stability of some oral liquid formulations containing 1 mg/ml captopril.

MATERIAL AND METHOD

The oral solutions were prepared using captopril substance, keeping the formulation as simple as possible to avoid potentially undesirable excipients. Samples were stored for 39 days below 8 degrees C and at 22 +/- 3 degrees C and analysed for physical, chemical and microbiological stability.

RESULTS

The formulations with ascorbic acid are stable for seven days either at 8 and 22 degrees C and could be prepared in hospital pharmacy as a more safely alternative to children terapy with tablets powders.

New method for determination of dydrogesterone in human plasma for therapeutic drug monitoring in gynecological disorders

A new simple, sensitive and selective liquid chromatography coupled with mass spectrometry (LC/MS) method for quantification of dydrogesterone in human plasma was validated.

MATERIAL AND METHOD

The analytes was eluted in 1.3 minutes on a reversed phase column (Zorbax SB-C18, 100 mm x 3.0 mm I.D., 3.5 microm) under isocratic conditions using a mobile phase of a 20 : 80 (v/v) mixture of ammonium acetate 1 mM and acetonitrile. The flow rate was 1 mL/min at the column temperature of 35 degrees C. The detection of the analyte was in MS/ MS mode using an atmospheric pressure chemical ionization source (APCI+, m/z 313 > m/z 295). The sample preparation was very simple and rapid and consisted in plasma protein precipitation from 0.2 mL plasma using 0.6 mL methanol.

RESULTS

Calibration curves were generated over the range of 5-150 ng/mL with values for coefficient of determination greater than 0.997 and by using a weighted (1/y) linear regression. The values of precision and accuracy were less than 12.5% and 7.5%, respectively, both for within- and between-run analysis. The mean recovery of the analyte was 99.8%. This is the first reported method for analysis dydrogesterone in human plasma that uses protein precipitation as sample processing procedure. The validated LC/MS method could be applied for determination of dydrogesterone in human plasma for therapeutic drug monitoring in gynecological disorders.

[Physico-chemical characterisation of Zn-flavonols complexes]

The aim of flavonols complexation is to improve their specific activity.

MATERIAL AND METHOD

The flavonols sources were Morus alba L. and Morus nigra L., zinc being the biological active ion. Physico-chemical characterization was made by thin-layer chromatography, UV-VIS spectrophotometry, IR spectrometry and polarography.

RESULTS

The complexes results were within acceptability limits, but their obtaining is economically inefficient.

New validated method for piracetam HPLC determination in human plasma

The new method for HPLC determination of piracetam in human plasma was developed and validated by a new approach. The simple determination by UV detection was performed on supernatant, obtained from plasma, after proteins precipitation with perchloric acid. The chromatographic separation of piracetam under a gradient elution was achieved at room temperature with a RP-18 LiChroSpher 100 column and aqueous mobile phase containing acetonitrile and methanol. The quantitative determination of piracetam was performed at 200 nm with a lower limit of quantification LLQ=2 microg/ml. For this limit, the calculated values of the coefficient of variation and difference between mean and the nominal concentration are CV%=9.7 and bias%=0.9 for the intra-day assay, and CV%=19.1 and bias%=-7.45 for the between-days assay. For precision, the range was CV%=1.8/11.6 in the intra-day and between-days assay, and for accuracy, the range was bias%=2.3/14.9 in the intra-day and between-days assay. In addition, the stability of piracetam in different conditions was verified. Piracetam proved to be stable in plasma during 4 weeks at -20 degrees C and for 36 h at 20 degrees C in the supernatant after protein precipitation. The new proposed method was used for a bioequivalence study of two medicines containing 800 mg piracetam.

Determination of loratadine and its active metabolite in human plasma by high-performance liquid chromatography with mass spectrometry detection

A new sensitive and selective liquid chromatography coupled with mass spectrometry (LC/MS/MS) method for quantification of loratadine (LOR) and its active metabolite descarboethoxyloratadine (DSL) in human plasma was validated. After addition of the internal standard, metoclopramide, the human plasma samples (0.3 ml) were precipitated using acetonitrile (0.75 ml) and the centrifuged supernatants were partially evaporated under nitrogen at 37 degrees C at approximately 0.3 ml volume. The LOR, DSL and internal standard were separated on a reversed phase column (Zorbax SB-C18, 100 mmx3.0 mm i.d., 3.5 microm) under isocratic conditions using a mobile phase of an 8:92(v/v) mixture of acetonitrile and 0.4% (v/v) formic acid in water. The flow rate was 1 ml/min and the column temperature 45 degrees C. The detection of LOR, DSL and internal standard was in MRM mode using an ion trap mass spectrometer with electrospray positive ionisation. The ion transitions were monitored as follows: 383-->337 for LOR, 311-->(259+294+282) for DSL and 300-->226.8 for internal standard. Calibration curves were generated over the range of 0.52-52.3 ng/ml for both LOR and DSL with values for coefficient of determination greater than 0.994 by using a weighted (1/y) quadratic regression. The lower limits of quantification were established at 0.52 ng/ml LOR and DSL, respectively, with an accuracy and precision less than 20%. Both analytes demonstrated good short-term, long-term, post-preparative and freeze-thaw stability. Besides its simplicity, the sample treatment allows obtaining a very good recovery of both analytes, around 100%. The validated LC/MS/MS method has been applied to a pharmacokinetic study of loratadine tablets on healthy volunteers.

New HPLC–MS method for quantitative determination of apovincaminic acid in human plasma

A fast and sensitive HPLC-MS method for the quantification of apovincaminic acid, a vinpocetine metabolite, in human plasma has been developed and validated. After protein precipitation with methanol, 10 mL of supernatant was injected at 45 degrees C onto a Zorbax SB-C18 column. Elution was performed in less than three minutes with water containing 0.2% formic acid and acetonitrile (80:20) at 0.75 mL/min. A linearity domain between 4 and 240 ng/mL and a limit of quantification of 4 ng/mL apovincaminic acid were established by monitoring the signal corresponding to m/z = 323. Accuracy and precision were less than 5.2% for within-run assay and 10% for between-run assay. The method was successfully applied in a bioequivalence study of two pharmaceutical products containing 5 mg vinpocetine.

[Qualitative determination of flavonoids and phenol-carboxylic acids of indigene Stachys species using HPLC method]

Indigene Stachys species have a high content in interesting compounds as iridoids, but also high quantities of flavonoids and phenol-carboxylic acids. These compounds present vasorelaxing effect on smooth vascular muscle interfering with metabolic degradation of nitric oxide pathways (inhibition of peroxynitrites formation) and by inhibition of phosphodiesterase. This work shows flavonoids spectrum of 3 Stachys species using HPLC methods. We identified quercetol, rutoside, miricetin and phenol-carboxylic acids (chlorogenic, caffeic and ferulic acids).

Validation of an HPLC method for the determination of ciprofloxacin in human plasma

A simple HPLC method with fluorescence detection of ciprofloxacin in human plasma was developed and validated. After protein precipitation, chromatographic separation of ciprofloxacin in plasma was achieved at 35 degrees C with a C18 column and acetonitrile-phosphate mixture, pH 3, as mobile phase. Quantitative determination was performed by fluorimetry after excitation at 278 nm. The method was specific and validated with a limit of quantification of 41 ng/ml. The intra- and inter-day coefficients of variation were between 0.5 and 6.6% and accuracy between -2.02 and 7.04%. Ciprofloxacin was stable in plasma for 40 days at -20 degrees C and after three freezing-thawing cycles. The method has been applied in a bioequivalence study of two formulation of 500 mg ciprofloxacin.

The study of codeine-gluthetimide pharmacokinetic interaction in rats

A high-performance liquid chromatographic (HPLC) assay with native fluorescence detection was developed for the simultaneous quantification of codeine and its two metabolites, morphine and morphine-3-glucuronide (M-3-G), in rat plasma. Solid-phase extraction was used to separate codeine and its metabolites from plasma constituents. Extraction efficiencies of codeine, morphine and M-3-G from rat plasma samples were 97, 92 and 93%, respectively. The chromatographic separation was performed using a reversed-phase C18 column and an elution gradient at ambient temperature. Using native fluorescence detection (excitation at 245 nm and emission at 345 nm), the detection limits of 50 ng/ml for morphine, 25 ng/ml for codeine and 20 ng/ml for M-3-G were obtained. The method had good precision, accuracy and linearity, and was applied to the study of glutethimide's influence on codeine metabolism in rat, following single doses of codeine-glutethimide association. The results confirmed the fact that glutethimide was responsible for a significant increase of morphine plasma levels and for their maintenance in time, concomitant with a significant decrease of M-3-G plasma levels, explained by the inhibition of morphine glucuronidation. In conclusion, glutethimide potentiates and prolongs the analgesic effect of codeine by a pharmacokinetic mechanism.

Characterization and lime treatment of olive mill wastewater

Seventeen olive mill wastewater (OMW) samples were characterized. For characterization of the samples, amount of total, fixed, volatile, suspended, volatile-suspended solids, COD, oil-grease, polyphenol, volatile phenol, nitrogen and reducing sugar were determined. Effects of lime treatment on the waste samples were investigated. Reduction of contents of the samples treated with the lime was described. The effect of the addition of lime on an artificial phenolic mixture was also examined.

High sensitivity to autoxidation in neonatal calf erythrocytes: possible mechanism of accelerated cell aging

The suspension viscosity, formation of methaemoglobin and production of malondialdehyde (MDA) associated with the non-enzymatic oxidation of polyunsaturated fatty acids during auto-oxidation conditions in vitro have been compared in erythrocytes from young calves (2, 4 and 6 weeks of age) and mature cattle. The autoxidation conditions were designed to simulate the oxidative stress to which neonatal erythrocytes are exposed in vivo. Characterisation of lipid peroxidation was also undertaken by a combination of lipid fluorescent measurements and quantification of the superoxide dismutase (SOD) activities of the erythrocytes. The results demonstrated that high SOD activities in the erythrocytes of the neonatal calf was insufficient to afford protection against the increased autoxidation of haemoglobin and subsequent accumulation of lipid peroxidation products. High levels of methaemoglobin formation and lipid peroxidation were able to provide an explanation for an observed reduction in rheological adaptability (increased suspension viscosity) and an accelerated aging of the neonatal cells under in vivo conditions.

[Effect of paracetamol on the acid hemolysis of erythrocytes, with special reference to the intracellular glutathione level]

The authors give account of their study concerning the effect of paracetamol on the acid haemolysis, and glutathione content of human erythrocytes. In vitro, paracetamol decreased intracellular glutathione content in a dose dependent manner. This may lead to an increased sensitivity of erythrocytes to the haemolytic effect of hydrochloric acid, what may explain the dose dependent decrease of time of haemolysis, presented in form of dynamic haemolysis curve. In vivo four hours following the oral intake of 500 mg paracetamol, although the intracellular glutathione content did not decrease significantly, shortening of the time of acid haemolysis could be demonstrated in more than half of the persons studied. No haemolysis was caused by the given dose of the drug.

The effect of silibinin (Legalon) on the the free radical scavenger mechanisms of human erythrocytes in vitro

The effect of Legalon was investigated parallel with that of Adriblastina (doxorubicin) and paracetamol on some parameters characterizing the free radical scavenger mechanisms of human erythrocytes in vitro and on the time of acid hemolysis performed in aggregometer. Observations suggest that Adriblastina enhances the lipid peroxidation of the membrane of red blood cells, while paracetamol causes significant depletion of intracellular glutathione level, thus decreasing the free radical eliminating capacity of the glutathione peroxidase system. Legalon on the other hand, is able to increase the activity of both superoxide dismutase and glutathione peroxidase, which may explain the protective effect of the drug against free radicals and also the stabilizing effect on the red blood cell membrane, shown by the increase of the time of full haemolysis.

[Auto-oxidation test for the determination of lipid peroxidation capacity of liver tissue homogenates of young and old mice]

The activity of superoxide dismutase (SOD) and the lipid-peroxidation capacity, i.e., the autoxidation of lipids during incubation at 37 degrees C for 3 h under aerobic conditions was measured in liver tissue homogenates of young (1.5-month-old) and old (24-month-old) inbred female Balb/c mice. The lipid peroxidation capacity was found to be significantly higher in young mice than in old ones. The pretreatment of young mice with allopurinol, a specific inhibitor of xanthine oxidase, remarkably decreased the lipid peroxidation capacity without any modification of SOD activity. SOD levels were equal in young and old mice. Our results suggest that the lipid peroxidation capacity of liver tissue depends, not only on the level of polyunsaturated fatty acids, but, in general, also on the state of a finely regulated counterbalance of pro- and antioxidant factors. The autoxidation test seems to be a suitable in vitro method for measuring the lipid peroxidation capacity of liver tissue.

Lipid peroxidation and superoxide dismutase activity in muscle and erythrocytes in adult muscular dystrophies and neurogenic atrophies

Lipid peroxidation (LP) and superoxide dismutase (SOD) activity were determined in erythrocytes and skeletal muscle obtained from patients with limb-girdle and facioscapulohumeral muscular dystrophies, neurogenic atrophies and from age-matched control subjects. Neither lipid peroxidation nor SOD activity in erythrocytes of patients differed from control values. SOD activity and LP in muscle specimens were also normal in types of neurogenic atrophy. Lipid peroxidation in the muscle from patients with adult types of muscular dystrophy had a tendency to be increased. The values were widely scattered, the highest being obtained in the older patients with long duration of disease.