A stability-indicating HPLC assay with on-line clean-up for betamethasone 17-valerate in topical dosage forms
- Authors: Smith, Eric W , Haigh, John M , Kanfer, Isadore
- Date: 1985
- Language: English
- Type: Article
- Identifier: vital:6421 , http://hdl.handle.net/10962/d1006556
- Description: A stability-indicating high-performance liquid chromatographic method with on-line clean-up has been developed for the analysis of betamethasone 17-valerate in topical dosage forms. A short pre-column containing 10 μm octadecylsilane mounted into the sample loop position of an injection valve was used as the primary clean-up step. The utilization of a diode-array UV detector allowed the quantitative analysis of betamethasone 17-valerate together with its degradation product, betamethasone 21-valerate, as well as the qualitative analysis of these compounds, relevant internal standards and the preservatives chlorocresol and methyl hydroxybenzoate contained in the cream and lotion formulations, respectively. Typically, cream and lotion dosage forms were dissolved in acetonitrile and ointments in tetrahydrofuran, internal standards added and aliquots injected onto the analytical system. Dosage form excipients were retained on the loop column and back-flushed to waste with the aid of a second solvent pump while components of interest were allowed to transfer to the analytical column for quantitative analysis. The method is accurate, precise and stability indicating and permits the rapid on-line analysis of betamethasone 17-valerate from complex topical formulation matrices without prior extractions.
- Full Text:
- Date Issued: 1985
Relative potencies of topical corticosteroid formulations
- Authors: Haigh, John M , Kanfer, Isadore , Meyer, Eric , Smith, Eric W
- Date: 1985
- Language: English
- Type: Article
- Identifier: vital:6375 , http://hdl.handle.net/10962/d1006291
- Description: It seems to us, and others (Burdick, 1974), that multiple reading times are essential to produce the response-time profile. Comparisons of potencies of topical corticosteroid formulations should only be made on the basis of area under the curve measurements and statistical treatment of all values obtained at each reading time throughout the course of the experiment.
- Full Text:
- Date Issued: 1985
Reply to correspondence: P.M. Gaylarde (1986) The human skin blanching assay—use and abuse
- Authors: Haigh, John M , Kanfer, Isadore , Meyer, Eric , Smith, Eric W
- Date: 1986
- Language: English
- Type: Article
- Identifier: vital:6376 , http://hdl.handle.net/10962/d1006293
- Description: Finally, we would like to assure Dr Gaylarde that we do not advocate the use of the human skin blanching assay. There are several other in vivo methods for determining corticosteroid activity which will provide equally meaningful results. What we are advocating is that if the human skin blanching assay is going to be used, then it should be used properly.
- Full Text:
- Date Issued: 1986
Aspects of the transdermal permeation and analysis of betamethasone 17-valerate
- Authors: Smith, Eric W
- Date: 1988
- Subjects: Transdermal medication Skin absorption Dermatologic agents
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3815 , http://hdl.handle.net/10962/d1004741
- Description: The current world-wide interest in transdermal drug delivery makes the prospect of valid in vitro diffusion cell methodology highly attractive. A new laboratory diffusion cell has been designed and constructed based on theoretical principles and practical permeation reports surveyed in recent literature, and has been applied to the monitoring of betamethasone 17-valerate permeation. The cell performance has been validated with respect to hydrodynamic mixing efficiency and temperature of the receptor phase. The steady-state permeation of this corticosteroid has been monitored through various synthetic and animal membranes in order to select the most appropriate media for in vitro study. The permeation of betamethasone 17-valerate has been monitored from various types of commercial and extemporaneously prepared semisolid topical formulation (cream, lotion, ointment and scalp application), through silicone membrane, human and weanling pig stratum corneum, and full thickness hairless mouse skin, and these in vitro results have been compared to data from in vivo blanching assays, using the same formulations, in an attempt to correlate the findings. This experimental methodology has necessitated the development of ancillary analytical techniques. A column-switching high-performance liquid chromatographic method has been developed for the rapid on-line clean-up and analysis of betamethasone 17-valerate contained in the various topical formulations, which minimizes sample handling and extraction procedures. The method has been modified for the analysis of this corticosteroid in the isopropyl myristate receptor phase used in the in vitro permeation experiments, and scintillation counting of tritium-labelled water has been used to verify the integrity of the animal membranes. The comparison of in vitro permeation and in vivo blanching results indicate good correlation of the data in certain instances. The closest correlations have been observed when the human stratum corneum has been used in vitro and these results are compared to data from the occluded mode of the blanching assay. The results of the porcine and murine media have also correlated with the human in vivo data, whereas the silicone membrane appears applicable only in certain in vitro experiments. The results indicate that valid, comparative percutaneous absorption data may be obtained in vitro by using a well designed, validated diffusion cell system.
- Full Text:
- Date Issued: 1988
Potency ranking of two new topical corticosteroid creams containing 0.1% desonide or 0.05% halometasone utilizing the human skin-blanching assay
- Authors: Meyer, Eric , Smith, Eric W , Haigh, John M , Kanfer, Isadore
- Date: 1988
- Language: English
- Type: Article
- Identifier: vital:6400 , http://hdl.handle.net/10962/d1006327
- Description: The human blanching assay was used to assess the potency of two new proprietary corticosteroid creams. The blanching abilities of 0.1% desonide cream and 0.05% halometasone cream were evaluated relative to the blanching elicited by 0.05% clobetasol 17-propionate cream, 0.1% betamethasone 17-valerate cream and 0.05% clobetasone 17-butyrate cream. The results of the trial indicated that the 0.1% desonide cream falls into the potent group of topical corticosteroid preparations and the 0.05% halomethasone cream falls into the moderately potent group.
- Full Text:
- Date Issued: 1988
In vitro diffusion cell design and validation. I. A stability-indicating high-performance liquid chromatographic assay for betamethasone 17-valerate in purified isopropyl myristate receptor phase
- Authors: Smith, Eric W , Haigh, John M
- Date: 1989
- Language: English
- Type: text , Article
- Identifier: vital:6431 , http://hdl.handle.net/10962/d1006595
- Description: Introduction: The development of a reliable in vitro permeation system necessitates the use of a precise and accurate method of quantifying the amount of permeant partitioning from the membrane into the cell receptor phase. Aqueous donor and receptor chamber fluids have been used in the majority of reported investigations, which makes quantitative permeant analysis relatively facile. Alternatively, radiolabelled diffusants have been used and flux rates monitored by scintillation counting, obviating the need for chromatographic separation of the receptor-phase components. However, this technique is not applicable when nonlabelled compounds or commercial dosage forms are to be evaluated by a cell system. Furthermore, several studies indicate that aqueous receptor phases may not present an optimal partitioning environment for certain lipophilic permeants (1-4), thereby impairing accurate flux monitoring due to limited diffusant solubility. Several attempts have therefore been made to improve the partitioning environment within these systems, by the addition of surfactants for example (4). A lipophilic receptor environment appears beneficial for corticosteroid partitioning, and thus, the use of isopropyl myristate has been investigated because of its bipolar properties that tend to mimic the biochemical composition of the skin (5,6). Betamethasone 17-valerate and its 21-valerate degradation product are highly soluble in isopropyl myristate and this nonaqueous solvent will not augment C-17-to-C-21 ester degradation reactions.
- Full Text:
- Date Issued: 1989
In vitro systems for the assessment of drug release from topical formulations and trans-membrane permeation
- Authors: Smith, Eric W , Haigh, John M
- Date: 1989
- Language: English
- Type: Book chapter
- Identifier: vital:6441 , http://hdl.handle.net/10962/d1006628
- Description: Numerous experimental methods have been developed to investigate drug release from vehicles and the percutaneous absorption of topically applied chemicals. The objective of this research is often to find correlation between laboratory results and the transdermal absorption experienced by living subjects so that in vivo experimentation may be curtailed. In many instances, the diverse experimental techniques tend to obscure absorption-controlling factors and complicate inter study comparisons, rather than clarify the complex transdermal absorption process. Moreover, lack of agreement between results may occasionally be ascribed to shortcomings in the in vitro methodology employed. The benefits of using an in vitro cell system for the preliminary testing of drug permeation in the laboratory are obvious. The environmental and diffusion variables may be controlled in an attempt to elucidate specific factors affecting the kinetic processes and drug bioavailability. Investigations are complex because of the multiple, interrelated events underlying the processes of drug partitioning from the applied vehicle and diffusion through the portals of the stratum corneum to the myriad of metabolic, binding, and clearance activities in the lower epidermal and dermal strata.
- Full Text:
- Date Issued: 1989
The human skin-blanching assay as an indicator of topical corticosteroid bioavailability and potency: an update
- Authors: Smith, Eric W , Meyer, Eric , Haigh, John M , Maibach, Harold I
- Date: 1989
- Language: English
- Type: Book chapter
- Identifier: vital:6440 , http://hdl.handle.net/10962/d1006627 , ISBN 0824780361
- Description: The human skin-blanching (or vasoconstrictor) assay has evolved from initial observations that corticosteroids induce a pallor or whitening of the skin to which they are applied. McKenzie and Stoughton (1962) are generally recognized as having developed the first scientific bioassay for comparing corticosteroid potency. The extensive use of this bioassay to compare drug release from topical delivery systems has demonstrated numerous instances in which the topical bioavailability may vary greatly, dependent on the character of the delivery vehicle. It has become evident that simply incorporating an intrinsically potent drug into a formulation does not necessarily produce a clinically efficacious product.
- Full Text:
- Date Issued: 1989
Blanching activities of betamethasone 17-valerate formulations: effect of the dosage form on topical drug availability
- Authors: Smith, Eric W , Meyer, Eric , Haigh, John M
- Date: 1990
- Language: English
- Type: Article
- Identifier: vital:6432 , http://hdl.handle.net/10962/d1006602
- Description: The blanching activities of Betnovate© cream, lotion, ointment and scalp application (each containing 0.1 % betamethasone (as the 17-valerate)) were determined using healthy human subjects over a 32 h period in both the occludedand unoccluded modes. Considering that allfour formulation types contained the same label concentration of corticosteroid,it may bepresumed that theformulations would show similar topical drug availability: this was, however, not found to be the case. The scalp application demonstrated the highest topical availability in both the occluded and unoccluded modes. The lotion formulation showed the greatest increase in topical availability on occlusion and the ointment formulation was the least sensitive to the effects of occlusion. These differences, due solely to the effects of the vehicle, may have important clinical implications.
- Full Text:
- Date Issued: 1990
The human skin-blanching assay for comparing topical corticosteroid availability
- Authors: Smith, Eric W , Meyer, Eric , Haigh, John M , Maibach, Harold I
- Date: 1991
- Language: English
- Type: Article
- Identifier: vital:6433 , http://hdl.handle.net/10962/d1006604
- Description: The human skin blanching assay remains in widespread use as a reliable, qualitative, comparative indicator of topical corticosteroid availability and potency. The experimental refinements promulgated by certain researchers in this field have yielded a versatile bioassay for the accurate assessment of new drugs or delivery vehicles. With the increasing appearance of generic topical corticosteroid formulations which compete with trade-name equivalents, the vital importance of this assay in regulatory affairs and assessing bioequivalence has been re-emphasized. It is stressed that if the blanching assay is to be used in this sphere, then multiple-reading trials must be conducted; important registration or clinical decisions cannot be made with any validity from short-term assessments.
- Full Text:
- Date Issued: 1991
Topical corticosteroid-induced skin blanching measurement, eye or instrument?
- Authors: Haigh, John M , Smith, Eric W
- Date: 1991
- Language: English
- Type: Article
- Identifier: vital:6378 , http://hdl.handle.net/10962/d1006296
- Description: We have read with interest a recent critique of the human skin blanching assay. We are concerned about the accuracy of statements and the interpretation of results presented in this publication. Having successfully employed this bioassay for over 15 years, and having noted similar, productive usage of this optimized technique reported from laboratories worldwide, the negativism expressed in the critique could dissuade potential researchers from employing this extremely useful assay procedure.
- Full Text:
- Date Issued: 1991
Accuracy and reproducibility of the multiple-reading skin blanching assay
- Authors: Smith, Eric W , Meyer, Eric , Haigh, John M
- Date: 1992
- Language: English
- Type: Book chapter
- Identifier: vital:6439 , http://hdl.handle.net/10962/d1006625
- Full Text:
- Date Issued: 1992
In vitro diffusion cell design and validation. II. Temperature, agitation and membrane effects on betamethasone 17-valerate permeation
- Authors: Smith, Eric W , Haigh, John M
- Date: 1992
- Language: English
- Type: text , Article
- Identifier: vital:6422 , http://hdl.handle.net/10962/d1006557
- Description: An in vitro permeation cell has been designed and validated for use in monitoring the transmembrane permeation of betamethasone 17-valerate. The design utilizes common laboratory equipment and incorporates as many beneficial features as possible from other designs. The importance of fully validating the hydrodynamic performance of the cell prior to experimentation is stressed. The cell was validated by monitoring the diffusion of betamethasone 17-valerate in isopropyl myristate solution into purified isopropyl myristate receptor phase at different temperatures, different agitation rates and through different synthetic and biological membranes. The results of the hydrodynamic validation agree with data from other researchers and show that the permeation cell is adequately sensitive to these experimental parameters. The results of the membrane evaluation allow appropriate selection of the barrier material for representative transdermal experiments to be conducted. While human and porcine stratum corneum/epidermis are similar in diffusive properties, hairless mouse skin appears to be the most convenient animal membrane for these studies. Although silicone and cellulose membranes appear to be useful in this application, porous filter membranes and egg-shell membranes are insufficiently discriminatory to betamethasone 17-valerate diffusion to provide useful in vitro permeation data.
- Full Text: false
- Date Issued: 1992
Sensitivity of different areas of the flexor aspect of the human forearm to corticosteroid-induced skin blanching
- Authors: Meyer, Eric , Smith, Eric W , Haigh, John M
- Date: 1992
- Language: English
- Type: Article
- Identifier: vital:6394 , http://hdl.handle.net/10962/d1006317
- Description: The intensity of corticosteroid-induced blanching has been found to vary at different areas of the flexor aspect of the human forearm. A retrospective analysis of 38,880 observations of skin blanching in 56 volunteers was conducted to assess the sensitivity of forearm skin to betamethasone 17-valerate. The mid-forearm appears to be more sensitive to the blanching response than do the areas close to the wrist or elbow. These results indicate that each preparation under evaluation should be applied to several sites along the forearm when using the human skin blanching assay in order to obtain an accurate comparative assessment of corticosteroid release from topical delivery vehicles.
- Full Text: false
- Date Issued: 1992
Ranking of topical corticosteroids: principles and results
- Authors: Smith, Eric W , Haigh, John M
- Date: 1993
- Language: English
- Type: text , Article
- Identifier: vital:6434 , http://hdl.handle.net/10962/d1006607
- Description: The increasing synthesis and use of topical corticosteroid products over the past 30 years has necessitated the development of suitable methods for evaluating the efficacy and potency of new drug entities. Several in vivo models have been developed in this regard using laboratory animals and human subjects. Generally, these tests measure the difference in the non-immunological inflammatory response to an exogenous inflammatory mediator in the presence and absence of the corticosteroid under test. There are also immunologically based assays and several tests which assess the anti proliferative effects of the drug. Several comparative disease model evaluations have also been developed using human subjects. Most of these assays are non-ideal from one point of view or another: most are invasive methods which require some form of trauma to be induced in the skin and therefore problematic to perform and monitor.
- Full Text:
- Date Issued: 1993
In vitro release of propranolol hydrochloride from topical vehicles
- Authors: Smith, Eric W , Haigh, John M
- Date: 1994
- Language: English
- Type: text , Article
- Identifier: vital:6435 , http://hdl.handle.net/10962/d1006612
- Description: Transdermal drug delivery is becoming increasingly important and for this reason it is clear that academia must ensure that current graduates are knowledgeable in all facets of topical drug administration. An in vitro diffusion cell experiment was designed to demonstrate the rate of release of propranolol hydrochloride (PHC) from three different topical vehicles: (i) an oil-in-water cream; (ii) a gel; and (iii) anointment. This experiment was performed by final-year students enroled in an undergraduate course on percutaneous absorption. In vitro release of PHC from the three bases to an aqueous receptor phase through silicone membrane was monitored spectrophotometrically at a wavelength of 290 nm. By monitoring and attempting to explain the numerous possible reasons for the different rates of drug release from the three vehicles, it was hoped that the students would gain a better understanding of the complexities of transdermal drug administration. Overall, the experiment would appear to be a good model for student investigation into factors affecting the release of drugs from topical formulations.
- Full Text:
- Date Issued: 1994
The selection and use of natural and synthetic membranes for in vitro diffusion experiments
- Authors: Haigh, John M , Smith, Eric W
- Date: 1994
- Language: English
- Type: text , Article
- Identifier: vital:6379 , http://hdl.handle.net/10962/d1006297
- Description: The following membranes are discussed: human skin; animal models (including mouse, hairless mouse, rat, guinea pig, rabbit, monkey, pig, shed snake skin, egg-shell membrane, and synthetic stratum corneum); and synthetic membranes (including cellulose media, filter membranes, and synthetic polymers). Membrane integrity and diffusive characteristics are also considered.
- Full Text:
- Date Issued: 1994
Assessing penetration enhances for topical corticosteroids
- Authors: Smith, Eric W , Haigh, John M
- Date: 1995
- Language: English
- Type: Book chapter
- Identifier: vital:6442 , http://hdl.handle.net/10962/d1006629
- Description: From introduction: Topical corticosteroids have been used for a wide range of dermatological conditions for the last 4 decades. For many years the topical delivery system was a relatively simple cream or ointment base, with little thought given to improving the formulation as far as drug delivery was concerned. The main emphasis in the initial stages of development was on the alteration of the corticosteroid molecule, in an attempt to produce moieties with a higher intrinsic topical effect with lower mineralocorticoid side effects. Once this avenue of research was exhausted, attention was placed on the lipophilicity of the molecule with the production of various types of esters in an attempt to produce molecules which would pass through the stratum corneum (SC) with reasonable ease. In recent years the nature of the semisolid drug delivery base has received considerable attention.2-5The nature of the vehicle has a profound effect on the rate of release of the topical corticosteroid from the formulation and its passage through the SC. One of the most important aspects of the formulation of the base is the inclusion of substances which aid this trads-SC diffusion, the so-called penetration enhancers.6The modes of action of the various different types of penetration enhancers are reviewed elsewhere in this book. The best method for the assessment of the release of corticosteroids from topical formulations is obviously the clinical tri~. Clinical trials, however, are laborious, costly, and difficult to mount. Patients suffering from dermatological complaints are not ideal subjects for the testing of topical corticosteroid formulations as it is difficult to obtain standardized lesions which are necessary for the comparison of results between formulations. Alternatively, a number of in vitro models exist for this type of assessment, but it is often problematic to obtain correlation with the in vivo situation.
- Full Text:
- Date Issued: 1995
In vivo/in vitro assessments of topical hydrocortisone availability: correlation between blanching assay and laboratory cell experiments
- Authors: Smith, Eric W , Haigh, John M
- Date: 1995
- Language: English
- Type: Book chapter
- Identifier: vital:6438 , http://hdl.handle.net/10962/d1006624
- Description: From introduction: Topical corticosteroids are still the most widely used drugs in the treatment of dermatological conditions. Early corticosteroid dosage forms consisted of simple creams or ointments where more emphasis was placed on the potency of the drug molecule than on the intrinsic delivery potential of the vehicle. More recently, the effect that the composition of the semisolid base has on the extent of drug delivery has been researched to a much greater extent. These advances in the science of dosage form design have necessitated the refinement of precise and accurate methods for testing the drug delivery efficacies of the developed products. Obviously, the best method for the assessment of the effectiveness of corticosteroid formulations is in a therapeutic situation. Clinical trials, however, are fraught with methodological problems that make duplication of a trial impossible. Alternatively, a number of pharmacological models4 exist for this type of assessment, but it is often problematic to obtain correlation with the true dermatological conditions. The human skin blanching assay is one of the most reliable and reproducible of the ill vivo methods available for the assessment of topical corticosteroid formulations. The skin whitening (blanching or vasoconstriction) side-effect that follows corticosteroid application was first utilized in 1962 as a measure of the percutaneous absorption of corticosteroids from topical formulations. Optimization of this initial procedure7.s has produced a reliable and precise bioassay methodology for the assessment of the efficacy of topical corticosteroid formulations. One criticism of this assay has been the subjective nature of the observation procedure. Although these points have repeatedly been addressed in the literature, it has been suggested that it would be beneficial to have some ill vitro penetration data to supplement ill vivo observations, as this would strengthen the assessment of the topical equivalence of similar delivery formulations. With this objective in mind, a comparison of hydrocortisone release from two proprietary cream formulations was compared by in vivo and ill vitro techniques to determine if any correlation could be established between the methodologies.
- Full Text:
- Date Issued: 1995
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.
- Full Text:
- Date Issued: 1995