Analysis of chromameter results obtained from corticosteroid-induced skin blanching. I. Manipulation of data
- Authors: Smith, Eric W , Haigh, John M , Walker, Roderick B
- Date: 1998
- Language: English
- Type: text , Article
- Identifier: vital:6424 , http://hdl.handle.net/10962/d1006559
- Description: Purpose. One of the unresolved issues in the FDA Guidance document for topical corticosteroid bioequivalence testing is the method of manipulation suggested for the chromameter data. The purpose of this study was to manipulate the instrumental data from a typical blanching study in a number of ways to investigate the appropriateness of these procedures for comparison with the subjective visually-assessed results. Methods. The human skin blanching assay methodology routinely practiced in our laboratories was utilised and the vasoconstriction produced by two corticosteroid formulations of different potency was assessed visually and instrumentally by use of a Minolta chromameter. The instrumental data were corrected for zero-time and unmedicated site readings. In addition, Euclidean distances were calculated using all data generated by the instrument. Results. Individually the a-, b- and L-scale chromameter values are imprecise and there is negligible vasoconstriction response recorded for the moderately potent formulation. Arithmetical manipulation of the data as suggested by the FDA does not appear to improve the quality of the data in any way. Euclidean distance analysis more closely resembles the visual data and appears to have better precision. Conclusions. It is clear that mathematical correction of chromameter data is unnecessary, especially since the instrumental data are extremely imprecise. Furthermore, the assessment of each individual chromameter index does not adequately characterise the blanching response profile. It is therefore suggested that Euclidean distance may be a better measure on which to base an analysis of bioequivalence than the truncated data set methodology currently suggested by the FDA.
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Analysis of macrolide antibiotics
- Authors: Kanfer, Isadore , Skinner, Michael F , Walker, Roderick B
- Date: 1998
- Language: English
- Type: Article , text
- Identifier: vital:7011 , http://hdl.handle.net/10962/d1008394 , http://www.sciencedirect.com/science/article/pii/S0021967398002763
- Description: The following macrolide antibiotics have been covered in this review: erythromycin and its related substances, azithromycin, clarithromycin, dirithromycin, roxithromycin, flurithromycin, josamycin, rokitamycin, kitasamycin, mycinamycin, mirosamycin, oleandomycin, rosaramicin, spiramycin and tylosin. The application of various thin-layer chromatography, paper chromatography, gas chromatography, high-performance liquid chromatography and capillary zone electrophoresis procedures for their analysis are described. These techniques have been applied to the separation and quantitative analysis of the macrolides in fermentation media, purity assessment of raw materials, assay of pharmaceutical dosage forms and the measurement of clinically useful macrolide antibiotics in biological samples such as blood, plasma, serum, urine and tissues. Data relating to the chromatographic behaviour of some macrolide antibiotics as well as the various detection methods used, such as bioautography, UV spectrophotometry, fluorometry, electrochemical detection, chemiluminescence and mass spectrometry techniques are also included.
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Evaluation of the proposed FDA pilot-dose response methodology for topical corticosteroid bioeqivalence testing [authors' reply in Letters to the Editor]
- Authors: Smith, Eric W , Walker, Roderick B , Haigh, John M , Kanfer, Isadore
- Date: 1998
- Language: English
- Type: text , Article
- Identifier: vital:6423 , http://hdl.handle.net/10962/d1006558
- Description: Reply to: Letter to the Editor by Singh GJ; Fleischer N; Lesko L; Williams R - relating to original article in Pharmaceutical Research (USA), Mar 1997, vol. 14, pp. 303-308.
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In vitro release of amoxycillin from lipophilic suppositories
- Authors: Webster, Jessica A , Dowse, Roslind , Walker, Roderick B
- Date: 1998
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/184377 , vital:44213 , xlink:href="https://doi.org/10.3109/03639049809085636"
- Description: The in vitro release characteristics of amoxycillin from different lipophilic suppository bases were investigated using the USP rotating basket method. Suppositories containing 250 mg amoxycillin were prepared in theobroma oil and in the semisynthetic bases Witepsol W35, Suppocire A32, Novata BD, and Novata 299. Both freshly prepared and 1-month-old suppositories were tested. Analysis of amoxycillin was performed using a validated high-performance liquid chromatographic (HPLC) technique. Release profiles differed significantly between bases, with the greatest amount of amoxycillin being released from both newly made and 1-month-old Novata BD bases (87.57 ± 8.18 and 99.66 ± 6.63%, respectively), and the lowest amount released from the newly manufactured theobroma suppositories (8.82 ± 0.75%) and the 1-month-old Suppocire A32 suppositories (7.78 ± 0.27%).
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