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Biomedical subjects

R B Stoughton

Publications and source records attributed to R B Stoughton.

At least 19 recordsLinked to original sources
PubMed1992

The vasoconstrictor assay in bioequivalence testing: practical concerns and recent developments.

The vasoconstrictor assay, when properly performed, is a highly reliable method to determine bioequivalence of generic formulations. Recent research has resolved some of the remaining questions concerning the practical application of the assay. Significant vehicle-related differences have been observed between the potency of different, supposedly equivalent formulations now on the market. Large differences in concentrations of the active agent in similar vehicles usually have not resulted in corresponding differences in vasoconstrictor assay results. Finally, the time course of drug effects may differ among highly potent and less potent corticosteroids. In general, the higher the potency of the topical corticosteroid, the earlier the maximal effect is observed. This finding suggests that short application of highly potent agents might minimize systemic absorption without sacrificing efficacy.

Administration, Topical↗
PubMed1990

Relation of application time to bioactivity of a potent topical glucocorticoid formulation.

The vasoconstrictor assay in human beings was used to assess bioavailability during different time periods of exposure when 0.05% clobetasol propionate cream (Temovate) was applied and left on for periods of 0.5, 1.0, 1.5, and 16.0 hours and subsequently washed. Maximal responses were achieved by 1.5 hours of exposure, but there was no significant difference in intensity of vasoconstriction between 1.0, 1.5, and 16.0 hours of exposure before washing the sites. Exposures to 0.05% clobetasol propionate cream for 0.5 hour were not significantly different from 16-hour exposures to 0.05% fluocinonide cream, but exposures to 0.05% clobetasol propionate cream for 1.0, 1.5, and 16.0 hours all resulted in significant increases in vasoconstriction responses compared with fluocinonide cream applied and left on for 16 hours. Topical exposures to a superpotent topical steroid for a short time give vasoconstrictor responses equivalent to long time exposures.

Administration, Cutaneous↗
PubMed1989

Percutaneous absorption of drugs.

Some practical applications of basic information in percutaneous absorption have been reviewed. Drug release from vehicles is discussed in relation to glucocorticosteroids. Penetration enhancers are reviewed with emphasis on the need for further investigations and applications of enhancers for clinical use. The role of the stratum corneum as a barrier to and a reservoir for drugs is discussed. Special problems in penetration as presented by regional anatomic variations, nails, and follicles are mentioned. Overall, we review some practical problems existing in the penetration of drugs through human skin.

Animals↗
PubMed1989

In vitro and in vivo cutaneous penetration and antifungal activity of naftifine.

The topical antifungal agent naftifine has shown considerable potency against a broad spectrum of dermatophytes. In this study, an in vitro penetration test in human cadaver skin and an in vivo tape-stripping test were used to evaluate the penetration and antifungal activity of naftifine gel 1 percent and naftifine cream 1 percent compared with other antifungal agents. In both models, Trichophyton rubrum and T. mentagrophytes were the fungal species. Results show that naftifine gel 1 percent and naftifine cream 1 percent, in vitro and in vivo, penetrate the stratum corneum in concentrations that inhibit the growth of both fungal species. Following penetration in vitro, naftifine gel and cream were significantly more active against T. rubrum than econazole nitrate cream 1 percent. Following penetration in vivo, naftifine gel and cream were as active as econazole nitrate cream 1 percent and clotrimazole cream 1 percent against T. rubrum and T. mentagrophytes.

Administration, Topical↗
PubMed1989

The same glucocorticoid in brand-name products. Does increasing the concentration result in greater topical biologic activity?

Many topical corticosteroid formulations are available as different concentrations of the steroid in a similar vehicle. We tested the existing assumption that higher concentrations give greater biologic activity. The vasoconstriction assay was used because of its known correlation with clinical activity. Statistical analyses of the different concentrations are as follows: Kenalog creams: 0.025% is equal to 0.1% is equal to 0.5%; Aristocort creams: 0.025% is equal to 0.1% is equal to 0.5%; Aristocort ointments: 0.1% is equal to 0.5%; Aristocort creams: 0.5% is equal to 0.025% but is less than 0.1%; Hytone cream: 1.0% is equal to 2.5%; Synalar creams: 0.01% is less than 0.025% which is less than 0.2%; Topicort creams: 0.25% is equal 0.05%; and Vallisone creams: 0.1% is greater than 0.01%. The assumption that increased concentration of the same steroid in the same vehicle type will give increased biologic activity is usually, but not always, incorrect for brand-name formulations now available.

Administration, Topical↗
PubMed1988

Erythromycin 2 percent gel in the treatment of acne vulgaris.

A gel formulation of erythromycin 2 percent was compared with its vehicle in a double-blind multicenter study involving patients with mild to moderate acne vulgaris. In an analysis of 187 patients treated twice daily for 8 weeks, erythromycin 2 percent gel proved to be significantly more effective than vehicle in reducing the numbers of both inflammatory and noninflammatory lesions. After 8 weeks, 60 percent of erythromycin-treated patients had good or excellent responses compared with 36 percent of those using vehicle (p = 0.001); the lesions in two patients using erythromycin were completely cleared. The majority of patients had a favorable impression of the cosmetic characteristics of the gel formulation.

Acne Vulgaris↗
PubMed1987

Efficacy of 4 percent chlorhexidine gluconate skin cleanser in the treatment of acne vulgaris.

We conducted three controlled, comparative studies to assess the effectiveness of a 4 percent chlorhexidine gluconate skin cleanser (Hibiclens) for the treatment of acne lesions in patients with acne vulgaris. In all studies, the chlorhexidine gluconate formulation achieved statistically significant reduction of the papules plus pustules count, which is generally accepted as the principal criterion of efficacy.

Acne Vulgaris↗
PubMed1987

Are generic formulations equivalent to trade name topical glucocorticoids?

Trade name glucocorticoid formulations triamcinolone acetonide, fluocinolone acetonide, and betamethasone valerate were compared with their generic equivalents because of increasing substitution of generic formulations for trade name formulations. The vasoconstrictor assay was the method used for these comparisons. Large differences were found between generic and trade name formulations containing the same steroid in the same concentration in both cream and ointment vehicles. If generic substitutions are to be used for trade name formulations, the physician must be aware that significant differences in therapeutic effectiveness may be expected.

Administration, Topical↗
PubMed1985

The effect of alclometasone dipropionate cream 0.05% on the hypothalamic-pituitary-adrenal axis of normal volunteers.

In an open study of ten evaluable normal volunteers, 30 g of alclometasone dipropionate cream 0.05% was applied to 80% of body surface each morning and evening for 21 days. A plastic body suit effectively occluded the treated area for 12 hours/day. As demonstrated by continued normal levels of 8 a.m. plasma cortisol and 24-hour urinary 17-hydroxysteroid and free cortisol, no suppression of the hypothalamic-pituitary-adrenal axis occurred. Local adverse reactions were mild and transient.

Administration, Topical↗
PubMed1985

Correlation of the vasoconstriction assay and clinical activity in psoriasis.

A large group of glucocorticosteroid formulations were assayed by the vasoconstriction test in normal skin sites and paired comparison studies in patients with psoriasis. Excellent correlation between the vasoconstriction assay and selected paired comparison studies occurred in 20 of 23 instances. In three instances, involving two glucocorticosteroid formulations tested, correlation was absent. The vasoconstrictor assay is an inexpensive and reliable method for screening glucocorticosteroid formulations for clinical activity in psoriasis.

Administration, Topical↗
PubMed1983

Psoriasis.

Explore the source record for details and available documents.

Humans↗
PubMed1982

Enhanced percutaneous penetration with 1-dodecylazacycloheptan-2-one.

1-Dodecylazacycloheptan-2-one (Azone) is a new agent that enhances the percutaneous absorption of a number of different chemicals. This report delineates the enhancement of penetration of clindamycin phosphate, erythromycin base, fusidate sodium, fluorouracil, desonide, amcinonide, and triamcinolone acetonide. For this purpose 1-dodecylazacycloheptan-2-one can be used in concentrations as low as 1%. It is colorless, relatively odorless, nontoxic, and can be applied neat to human skin without any irritation.

Administration, Topical↗
PubMed1981

Topical clindamycin therapy for acne vulgaris. A cooperative clinical study.

Eleven institutions participated in an eight-week controlled clinical study to evaluate treatment of acne vulgaris with topical clindamycin hydrochloride and clindamycin phosphate. Three hundred fifty-eight patients with comparable baseline pustule, papule, and nodule counts applied 1%, clindamycin hydrochloride, 1% clindamycin phosphate, or a hydroalcoholic vehicle twice daily. Every two weeks, lesions were counted, and patients' evaluations of their acne conditions were scored. By week 8, pustule and papule counts in the groups who were receiving clindamycin were significantly lower than those in the group receiving placebo. Also, more patients who were receiving clindamycin thought their acne improved by week 8 (with significantly higher change-in-acne scores) than did the patients receiving placebo. Patients receiving clindamycin reported 12 episodes of diarrhea; only one episode was considered to be treatment related. These results substantiate the clinical impression that topical clindamycin is effective treatment for acne.

1-Propanol↗
PubMed1981

A clinical screening program for topical chemotherapeutic drugs in psoriasis.

In this national, multicenter cooperative study, a standardized drug screening program was designed and evaluated to test the clinical effectiveness of 30 topically applied chemotherapeutic drugs to psoriasis. Appropriate concentrations and vehicles for topical administration were selected with regard to clinical testing consisted of a double-blind application of test agents to psoriatic plaques under occlusion daily for up to nine days. Drugs known to be topically active in psoriasis, eg, thiotepa, fluorouracil, and betamethasone valerate, were easily detected in the clinical protocol, confirming the validity of this topical drug screening program. Seven drugs produced substantial clinical improvement with evidence of clearing; nine drugs produced slight improvement; 14 drugs had no effect. No systemic toxid reactions occurred. This screen should be useful to test other potential antipsoriatic drugs and to evaluate potential animal model screens for their predictive values with the same drugs.

Adult↗