Comparison of visual CR-200 and CR-300 chromameter data obtained from the corticosteroid-induced skin-blanching assay
- Authors: Schwarb, Fabian P , Smith, Eric W , Haigh, John M , Surber, Christian
- Date: 1998
- Language: English
- Type: Conference paper , text
- Identifier: vital:6344 , http://hdl.handle.net/10962/d1006611
- Description: In a recent Guidance document the American FDA recommended the use of a chromameterrather thanthe human eye for the assessment of the pharmacodynamic blanching response produced after topical application of corticosteroids. The purpose of this study was to investigate the appropriateness of the human eye and two types of chromameter for the estimation of skin blanching.
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- Date Issued: 1998
The requirements for accurate analysis of pharmaceutical research at South African Universities
- Authors: Haigh, John M , Smith, Eric W
- Date: 1998
- Language: English
- Type: text , Article
- Identifier: vital:6367 , http://hdl.handle.net/10962/d1006067
- Description: International Pharmaceutical Abstracts is a valuable database for pharmaceutical research, although the multisiciplinary nature of this field implies that the database should only be the starting point of a search. This database is totally inappropriate for comparing outputs of individual pharmacy teaching institutions.
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- Date Issued: 1998
The use of supersaturated solutions for the percutaneous delivery of rooperol tetra-acetate
- Authors: Pefile, S C , Haigh, John M , Smith, Eric W
- Date: 1998
- Language: English
- Type: Conference paper , text
- Identifier: vital:6340 , http://hdl.handle.net/10962/d1006537
- Description: A major problem encountered in the transdermal delivery of drugs is the effectiveness of the barrier system imposed by the stratum corneum.To overcome tbe resistance of the skin to the ingress of exogenous chemicals, numerous innovative techniques requiring complex delivery systems have been studied. Many of these systems attempt to alter the barrier potential by the use of enhancer technology. Supersaturation, on the other hand, is a simple and economical technique which is not intended to modify the physical structure or the chemical composition of the stratum corneum, yet may effectively deliver a markedly greater mass of drug to the skin than that achieved by the use of conventional, saturated solutions. Supersaturated systems make use of the elevated thermodynamic activity of the permeant in the delivery vehicle, which results in higher flux rates across the contacting membrane by increasing the concentration gradient. The present study investigated the potential for using supersaturation techniques to transdermally deliver rooperol tetra-acetate (RTA), a lipophilic, cytotoxic agent with potential for use in the treatment of solar keratosis. The diffusion characteristics of the drug from a 60% propylene glycol/water supersaturated solution across silicone membrane and full thickness rat skin were studied using Franz diffusion cells. A comparison was made of the drug diffusion rates from a saturated system and from supersaturated systems prepared with and without an antinucleating agent.
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- Date Issued: 1998
The effects of elevated and ambient temperature conditions on dilutions of fluocinolone acetonide ointment assessed using the human skin-blanching assay
- Authors: Haigh, John M , Smith, Eric W
- Date: 1995
- Language: English
- Type: text , Article
- Identifier: vital:6380 , http://hdl.handle.net/10962/d1006298
- Description: Topical corticosteroid formulations have been in use now for some 30 years and many methods are available for the in vivo assessment of these preparations. Of all the assays described in the literature, the one first advocated by McKenzie and Stoughton, the so-called vasoconstrictor assay, is one of the most reliable if performed by experienced researchers using - the optimised methodology. Topical application of corticosteroids produces a whitening (blanching) of the skin, the intensity of which is directly proportional to the clinical efficacy of the formulation. Assessment of the degree of blanching produced is therefore of use in determining the rate and extent of corticosteroid release' from the semi-solid base through the stratum corneum. Since it is the degree of blanching which is measured, we prefer to call this test the human skin blanching assay. Some of the main advantages of this assay technique are that normal healthy skin is used therefore persons with dermatological complaints are not compromised, it is not painful for the volunteers, it is non-invasive and several formulations can be evaluated simultaneously. Most commercially available topical corticosteroid preparations have been formulated in such a way as to provide optimum release of the active ingredient from the base through the stratum corneum. Despite this fact, many practitioners often prescribe dilutions of topical corticosteroid formulations, presumably in an effort to reduce the unwanted side effects. This could be problematic; dilution with an incompatible base could destroy the delivery environment thus considerably reducing the efficacy of the formulation. The method of dilution could also play a role in the suitability of the final preparation. The objective of this work was to determine the effects of two different dilutions of fluocinolone ointment at both ambient and elevated temperature on the blanching produced by the dilutions and, by inference, the relative clinical efficacies of these dilutions compared to the full strength product.
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- Date Issued: 1995