Simultaneous determination of pregnenolone and 17α-hydroxypregnenolone by semi-micro high-performance liquid chromatography with an immobilized cholesterol oxidase as a pre-column reactor: application to bovine adrenal fasciculata cells.

A method for the simultaneous determination of pregnenolone and 17α-hydroxypregnenolone by high-performance liquid chromatography with an immobilized cholesterol oxidation enzyme reactor was developed. Pregnenolone and 17α-hydroxypregnenolone were converted to progesterone and 17α-hydroxyprogesterone, respectively, by the immobilized enzyme packed into the reactor column, and could thus be monitored by UV absorption at 240 nm. The calibration curves for pregnenolone and 17α-hydroxypregnenolone were linear in the range of 0.4-10 and 0.3-10 µg/ml with a correlation coefficient of 0.9993 and 0.9998, respectively. The detection limit at a signal-to-noise ratio of 3 was 0.12 and 0.08 µg/ml for pregnenolone and 17α-hydroxypregnenolone, respectively. The conversion rate of pregnenolone to progesterone and 17α-hydroxypregnenolone to 17α-hydroxyprogesterone was 90.6% and 99.3%, respectively. Intra-day and inter-day precision (in terms of percentage coefficient of variation) were less than 9.3%, with accuracy greater than 94.8%. This method was successfully applied to the simultaneous determination of pregnenolone and 17α-hydroxypregnenolone secreted into the culture medium of bovine adrenal fasciculata cells and of both analytes produced within the cells.

Granulation of core particles suitable for film coating by agitation fluidized bed III. Effect of scale, agitator rotational speed and blade shape on granule properties and development of a high accuracy scale-up theory.

The preparation of core particles suitable for subsequent film coating was examined using different scales of agitation fluidized beds. Specifically, the effects of agitator rotational speed and agitator blade shape in different scales of granulators on granule properties such as mass median diameter, apparent density, friability and shape factor were studied. As the agitator rotational speed was increased or when the agitator blade height and angle were large, the mass median diameter and friability of the granules decreased, while the apparent density and shape factor increased, in a manner independent of the vessel size because the granules were subjected to greater compression, shearing and rolling effects. The same core particles could not be prepared using granulators with different vessel sizes by simply adopting a conventional scale-up theory(1,2)) based on kinetic energy similarity. Here, a novel scale-up theory that takes into account agitator blade shape factors is proposed.(3)) When the two scale-up theories were compared, our new theory was capable of predicting the granule properties more accurately than the conventional theory. By adopting this novel theory, the same core particles could be prepared under different operating conditions in any scale of granulator.

Granulation of core particles suitable for film coating by agitation fluidized bed II. A proposal of a rapid dissolution test for evaluation of bitter taste of ibuprofen.

To prepare powdered drugs that do not have a bitter taste, a film coating covering the surfaces of the core particles is required. The dissolution rate of ibuprofen from the coated particles changes according to the physical properties of the core particles. In this study, the effects of the physical properties of granules prepared by using several scales of agitation fluidized beds on the drug dissolution rate were investigated. The dissolution rate of ibuprofen decreased when the apparent density and shape factor of the granules increased. In contrast, the dissolution rate of the drug increased with the friablility of the granules increased. Thus, the structures of the granules appear to affect the dissolution rate of the drug to a large degree. A rapid dissolution test that can be used to investigate the early dissolution rate of ibuprofen in vitro was proposed to evaluate the taste-masking level of the coated particles. The bitter taste-masking level of the coated particles was successfully confirmed by using this novel test method.

Granulation of core particles suitable for film coating by agitation fluidized bed I. Optimum formulation for core particles and development of a novel friability test method.

To prepare powdered medicines without bitter taste, film coating is required to cover the surface of core particles. In this study, effect of formulation and operating conditions of agitation fluidized bed on the core particle properties was investigated. In order to prevent breakage of the core particles during coating process, which sometimes causes variation of drug dissolution rate, addition of maltose syrup powder during the formulation process of the core particles was investigated. Also, a method for friability test in which the core particles were subjected to strong impact was proposed to evaluate strength of the core particles. The friability of the core particles determined by this test method correlated well with the actual friability of the particles during the coating process. Based on this result, we confirmed this novel friability test method could predict the core particle endurance during the coating process.

Simultaneous determination of active ingredients in an ophthalmic solution by isocratic tandem-mode HPLC connected reverse phase column and strong cation exchange column.

A tandem-mode high performance liquid chromatography (HPLC) system is described here, which employs reversed phase liquid chromatography (RPLC) followed by strong cation exchange liquid chromatography (SCX), was used to determine the mixture of six ingredients in an ophthalmic solution. As a result of investigations, isocratic HPLC methods that using two columns in tandem-mode; Atlantis dC18 (75 mm x 4.6 mm i.d., 3 microm, ODS) and CAPCELL PAK SCX UG80 (75 mm x 4.6 mm i.d., SCX), which have different separation modes, and control of mixture of methanol/ammonium dihydrogenphosphate buffer as used for the eluent, allowed for six target ingredients to be determined simultaneously. And all ingredients separated perfectly and were determined efficiently and rapidly. Validation of the method was accomplished with respect to linearity (r>0.999), recovery (99.4-100.4%), precision (R.S.D. 0.1-0.9%) and specificity. These results suggest that the fusion of different separation modes can be used for the simultaneous determination of ingredients in ophthalmic solutions, and this can be accomplished rapidly and with high precision.

Simultaneous determination of ingredients in a cold medicine by cyclodextrin-modified microemulsion electrokinetic chromatography.

Cyclodextrin-modified microemulsion electrokinetic chromatography (CD-MEEKC) was used to simultaneously determine 14 active ingredients (thiamine nitrate, anhydrous caffeine, acetaminophen, riboflavin, guaifenesin, pseudoephedrine hydrochloride, ascorbic acid, ethenzamide, DL-methylephedrine hydrochloride, dihydrocodeine phosphate, ibuprofen, noscapine, carbinoxamine maleate, and bromhexine hydrochloride) in a cold medicine. Separation of the ingredients was optimized by changing the SDS concentration and oil type and the addition of 2-propanol and cyclodextrin (CD) to the separation solution. The separation selectivity was improved dramatically by changing CD type. All of the active ingredients and formulation excipients were successfully separated with the use of a separation solution consisting of 0.81% (w/w) pentane, 6.61% (w/w) 1-butanol, 2% (w/w) 2-propanol, 4.47% (w/w) SDS, and 86.11% (w/w) 10 mM sodium tetraborate solution with 3 mM 2,6-di-O-methyl-beta-CD. The established method was then validated and demonstrated to be applicable to the determination of the active ingredients in a model cold medicine. No interference from the formulation excipients was observed. Good linearities were obtained with correlation coefficients above 0.999. Recovery and precision ranged from 99.1 to 100.7% and from 0.5 to 2.8% R.S.D., respectively. The detection limit for ingredients ranged from 0.6 to 4.2 microg ml(-1). Good agreement was obtained between the established method and the traditional HPLC method. These results suggest that CD-MEEKC can be used for the determination of multiple ingredients in cold medicine.

Uniformly sized molecularly imprinted polymer for atropine and its application to the determination of atropine and scopolamine in pharmaceutical preparations containing Scopolia extract.

A uniformly sized molecularly imprinted polymer (MIP) for atropine has been prepared. The MIP was prepared using 2-(trifluoromethyl) acrylic acid and ethylene glycol dimethacrylate as a functional monomer and cross-linker, respectively, by a multi-step swelling and thermal polymerization method. The selectivity factor, which is defined as the ratio of the retention factors (k) on the molecularly imprinted and non-imprinted polymers, k(imprinted)/k(non-imprinted), was 2.2 for atropine on the MIP. The obtained MIP was applied for the determination of tropane alkaloids (atropine and scopolamine) in a commercial gastrointestinal drug by a column-switching HPLC system, consisting of an MIP material as a pre-column, and a conventional cation-exchange analytical column. An interference peak was observed at the retention time of atropine derived from pre-column. However, since the peak area was less than 0.5% the peak area of atropine of a standard solution under the analytical conditions of this study (0.2 microg of atropine was loaded), this interference was negligible in the determination of atropine. On the other hand, no interference peak was observed at the retention time of scopolamine. Calibration curves of atropine and scopolamine showed good linearity in the range of 0.02-0.9 microg/ml (r=0.9999) and 0.003-0.09 microg/ml (r=0.9998), respectively. The mean recoveries of atropine and scopolamine from a placebo pharmaceutical preparation sample were 98.9 and 99.9%, respectively. The intra-day precision (measured by relative standard deviation, R.S.D. (%)) of both ingredients was less than 2.0%. The optimized column-switching system was applied successfully to the determination of atropine and scopolamine in a commercial gastrointestinal drug.