Assessing penetration enhances for topical corticosteroids
- Smith, Eric W, Haigh, John M
- 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
- 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
Foam drug delivery in dermatology: beyond the scalp
- Purdon, Carryn H, Haigh, John M, Surber, Christian, Smith, Eric W
- Authors: Purdon, Carryn H , Haigh, John M , Surber, Christian , Smith, Eric W
- Date: 2003
- Subjects: Adis International Limited , Drug delivery systems , Skin disorders
- Language: English
- Type: text , Article
- Identifier: vital:6418 , http://hdl.handle.net/10962/d1006541
- Description: Consumers of topical formulations apply a wide spectrum of preparations, both cosmetic and dermatological, to their healthy or diseased skin. These formulations range in physicochemical nature from solid through semisolid to liquid. Pharmaceutical foams are pressurized dosage forms containing one or more active ingredients that, upon valve actuation, emit a fine dispersion of liquid and/or solid materials in a gaseous medium. Foam formulations are generally easier to apply, are less dense, and spread more easily than other topical dosage forms. Foams may be formulated in various ways to provide emollient or drying functions to the skin, depending on the formulation constituents. Therefore, this delivery technology should be a useful addition to the spectrum of formulations available for topical use; however, as yet, only a few are commercially available. Probably the most convincing argument for the use of foams is ease of use by the patient, and consumer acceptance. Most foam dosage forms used in dermatology to date have incorporated corticosteroids, although some products have also been used to deliver antiseptics, antifungal agents, anti-inflammatory agents, local anesthetic agents, skin emollients, and protectants. Although there is no clinical evidence that foam formulations are currently superior to other conventional delivery vehicles, these formulations have a clear application advantage and with continued developments in the science of supersaturation technology, it seems certain that foam delivery systems will retain their place in the dermatological and cosmetic armamentarium.
- Full Text:
- Date Issued: 2003
- Authors: Purdon, Carryn H , Haigh, John M , Surber, Christian , Smith, Eric W
- Date: 2003
- Subjects: Adis International Limited , Drug delivery systems , Skin disorders
- Language: English
- Type: text , Article
- Identifier: vital:6418 , http://hdl.handle.net/10962/d1006541
- Description: Consumers of topical formulations apply a wide spectrum of preparations, both cosmetic and dermatological, to their healthy or diseased skin. These formulations range in physicochemical nature from solid through semisolid to liquid. Pharmaceutical foams are pressurized dosage forms containing one or more active ingredients that, upon valve actuation, emit a fine dispersion of liquid and/or solid materials in a gaseous medium. Foam formulations are generally easier to apply, are less dense, and spread more easily than other topical dosage forms. Foams may be formulated in various ways to provide emollient or drying functions to the skin, depending on the formulation constituents. Therefore, this delivery technology should be a useful addition to the spectrum of formulations available for topical use; however, as yet, only a few are commercially available. Probably the most convincing argument for the use of foams is ease of use by the patient, and consumer acceptance. Most foam dosage forms used in dermatology to date have incorporated corticosteroids, although some products have also been used to deliver antiseptics, antifungal agents, anti-inflammatory agents, local anesthetic agents, skin emollients, and protectants. Although there is no clinical evidence that foam formulations are currently superior to other conventional delivery vehicles, these formulations have a clear application advantage and with continued developments in the science of supersaturation technology, it seems certain that foam delivery systems will retain their place in the dermatological and cosmetic armamentarium.
- Full Text:
- Date Issued: 2003
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
- Smith, Eric W, Haigh, John M
- 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
- 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
The human skin-blanching assay for in vitro topical corticosteroid assessment. I. Reproducibility of the assay
- Haigh, John M, Meyer, Eric, Smith, Eric W, Kanfer, Isadore
- Authors: Haigh, John M , Meyer, Eric , Smith, Eric W , Kanfer, Isadore
- Date: 1997
- Language: English
- Type: text , Article
- Identifier: vital:6381 , http://hdl.handle.net/10962/d1006299
- Description: The human skin blanching (vasoconstriction) assay for the assessment of topical corticosteroids has been in use for over 30 years, the intensity of the drug-induced blanching being assessed subjectively by eye. Both arms of several male and female volunteers are used for product application and more than one observer is used to estimate the degree of induced blanching. There are, therefore, numerous variables which are inherent in the assay procedure. This investigation consisted of three identical trials performed at 8-week intervals, utilising the same 18 volunteers and the same three observers in an attempt to address the question of reproducibility of the assay. From the results obtained it is clear that the assay methodology is capable of consistently distinguishing, on a rank order basis, between preparations which show similar blanching (chemically-equivalent formulations). The similarity of the results for the three individual trials gives considerable confidence to results produced using this methodology. An experiment designed to test the reproducibility of the blanching scores showed that the observers are capable of producing identical results even though visual observation is highly subjective.
- Full Text:
- Date Issued: 1997
- Authors: Haigh, John M , Meyer, Eric , Smith, Eric W , Kanfer, Isadore
- Date: 1997
- Language: English
- Type: text , Article
- Identifier: vital:6381 , http://hdl.handle.net/10962/d1006299
- Description: The human skin blanching (vasoconstriction) assay for the assessment of topical corticosteroids has been in use for over 30 years, the intensity of the drug-induced blanching being assessed subjectively by eye. Both arms of several male and female volunteers are used for product application and more than one observer is used to estimate the degree of induced blanching. There are, therefore, numerous variables which are inherent in the assay procedure. This investigation consisted of three identical trials performed at 8-week intervals, utilising the same 18 volunteers and the same three observers in an attempt to address the question of reproducibility of the assay. From the results obtained it is clear that the assay methodology is capable of consistently distinguishing, on a rank order basis, between preparations which show similar blanching (chemically-equivalent formulations). The similarity of the results for the three individual trials gives considerable confidence to results produced using this methodology. An experiment designed to test the reproducibility of the blanching scores showed that the observers are capable of producing identical results even though visual observation is highly subjective.
- Full Text:
- Date Issued: 1997
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