The human nail penetration of the antifungal ciclopirox was determined for marketed gel containing 0.77% of ciclopirox, an experimental gel containing 2% of ciclopirox, and a marketed lacquer containing 8% of ciclopirox. After 14 days dosing, unabsorbed drug remaining on the surface, drug within the infection-prone area, and the amount that had penetrated through the nail were determined. Ciclopirox delivery into and through the nail was significantly greater from the marketed gel, than from either the experimental gel or the nail lacquer (p < 0.05). In addition, the surface nail contained more unabsorbed drug from the lacquer. Further, the drug penetrating into and through the nail was also greater from the marketed gel, leading to a higher Calculated Efficacy Coefficient for the marketed gel, than from the marketed lacquer or the experimental gel. The formulation plays an important role in the enhancement of ciclopirox permeation into and through the human nail plate, and the concentration of ciclopirox in the formulation was not a factor in determining penetration.

BACKGROUND: Benzoyl peroxide and clindamycin are the two most widely prescribed topical antimicrobials in the treatment of acne.AIM: To compare the antimicrobial efficacy, in vivo, of benzoyl peroxide and clindamycin against Propionibacterium acnes.METHODS: Two groups of 10 subjects each, with comparable mean P. acnes baseline counts of log 5.75 to 5.85, underwent twice daily application of benzoyl peroxide or clindamycin for 14 days.RESULTS: The results of quantitatively sampling P. acnes after 3, 7 and 14 days of treatment showed that Triaz(TM) 6% benzoyl peroxide special gel produced faster and significantly greater reductions in P. acnes than did the 1% clindamycin phosphate in Cleocin-T(TM) lotion (p < 0.01). These results were paralleled by the greater reductions produced by Triaz versus Cleocin (p < 0.05) in P. acnes fluorescence.CONCLUSION: Benzoyl peroxide formulations suppress the follicular population of P. acnes more rapidly and to a greater degree than topical antibiotics such as clindamycin.

Xerosis is an extraordinarily common problem in dermatology. Despite the knowledge of well recognized aggravating factors, its etiology is an enigma, and the management of the condition is often suboptimal. Dry skin may be a manifestation of hypothyroidism. The nature of this association is reviewed, culminating in the speculation that topical thyroid hormone may represent a useful modality in euthyroid patients with xerosis or other disorders of keratinization.

BACKGROUND: All-trans-retinol was the first vitamin to be synthesized in the laboratory. Dermatologic research with this agent, first begun in the 1960s, was discontinued because of its instability. Investigations since then have focused primarily on a metabolite of vitamin A, all trans-retinoic acid, for the treatment of various dermatological disorders. TREATMENT: While topically applied retinoic acid is effective in reducing the signs of intrinsic aging and repairing photodamaged skin, depending on the concentration it causes a number of irritant effects, including erythema, peeling, dryness, and pruritus in some patients. This drawback stimulated renewed efforts to find a less irritating retinoid. ADVANCES: As a result of advances in the cosmetic industry, retinol is now being produced in a stable formulation, and is again commanding the attention of investigators. CONCLUSION: Clinical trials conducted so far indicate that, like retinoic acid, retinol can induce changes that have a beneficial effect on the epidermis but with decreased irritation. (J Dermatol Treat (2000) 11:47–52)

In two recent, separate in vivo antimicrobial studies, orally administered Dynacin(R) (minocycline HCl) produced superior reduction of Propionibacterium acnes compared with doxycycline and tetracycline, and topically applied Triaz(R) (benzoyl peroxide special gel) produced comparably superior reduction in P. acnes compared with clindamycin phosphate lotion and azelaic acid cream. These findings stimulated interest in evaluating the in vivo antimicrobial efficacy of the combination of Dynacin :LOG mg twice daily orally, and topical Triaz 10% gel twice daily, each used daily for 6 weeks, with measurement of the residual antimicrobial effect 3 weeks post-dosage. After 3 weeks of treatment, there was a substantial, 2.5 log reduction in P. acnes from a baseline log count of 6.21 (1 112 000 organisms) to 3.52 (3311 organisms). After 6 weeks on this combination therapy, the reduction in P. acnes was dramatic; a count of log 2.24 or only 173 organisms was found. All reductions were statistically significant compared with baseline (P=<0.01). At 3 weeks after therapy had ceased, the level of P. acnes was still reduced significantly (P=<0.01) compared with baseline.

This single-blind, 4-week study compared the in vivo antimicrobial efficacy of three topical antimicrobial products used to treat acne: Triaz(R) 10% Gel (benzoyl peroxide special gel), Azelex(R) Cream (azelaic acid cream), and 2% Cleocin-T(R) Lotion (clindamycin phosphate lotion). There were three parallel groups, each containing males and females with minimum baseline Propionibacterium acnes of 10 000 colony forming units per cm(2). Each product was applied twice daily for 4 weeks and P. acnes was sampled using the scrub procedures of Williamson and Kligman on the forehead and both cheeks, at baseline and at 2 and 4 weeks. The results showed that Triaz Gel produced substantial and significantly superior reductions in P. acnes, compared with those produced by Cleocin-T Lotion and Azelex Cream as early as 2 weeks and continuing through 4 weeks of treatment (P=<0.01). Further, while Triaz Gel and Cleocin-T Lotion produced significant reductions in P. acnes compared with baseline after 2 and 4 weeks, Azelex Cream appeared to produce no reduction in P. acnes at either time point.

Triaz 10% Gel (benzoyl peroxide special gel) is a topical, 10% benzoyl peroxide acne medication with a vehicle containing glycolic acid and zinc lactate. This 12-week study, using lesion counts and assessment of adverse effects, was designed to compare the efficacy and safety of benzoyl peroxide special gel with Benzamycin (5% benzoyl peroxide and 3% erythromycin) in the treatment of moderate to moderately severe, papular-pustular, facial acne vulgaris. A placebo base served as a control. Over 3 months of therapy with twice-daily application, benzoyl peroxide special gel was at least comparable to benzoyl peroxide-erythromycin in reducing inflamed lesions (papules+pustules), noninflamed lesions (open+closed comedones) and the total of these lesions. Moreover, benzoyl peroxide special gel was significantly less drying.

In addition to the importance of bioavailability to reliable therapy, the three leading tetracyclines used in the treatment of acne have dissimilar tissue distributions and lipophilic characteristics which may impart different antimicrobial efficacy. The purpose of this study was to compare the in vivo antimicrobial effects of minocycline, doxycycline and tetracycline. The results of this study confirm that normal dosages of minocycline hydrochloride capsules in fast-release powder form produced significantly superior in vivo reductions in Propionibacterium acnes compared to that produced by normal dosages of doxycycline monohydrate and tetracycline hydrochloride. In addition, minocycline produced much greater residual antimicrobial activity than the other two drugs after the end of the treatment period.

The bactericidal effects of benzoyl peroxide (5% lotion) and hexachlorophene (3% colloidal suspension) against Propionibacterium acnes were compared in nine healthy college students who had the microbiological and skin lipid characteristics typical of acne vulgaris, but no active lesions. Each of the two medications was applied twice daily, to opposite sides of the face, for four consecutive weeks. Hexachlorophene was effective against surface aerobes but only slightly active against P acnes. It marginally reduced free fatty acid concentrations in surface lipids and in follicular porphyrin fluorescence. Conversely, benzoyl peroxide virtually eliminated P acnes and aerobes and induced substantially decreased free fatty acid concentrations and follicular fluorescence. We conclude that benzoyl peroxide exerts its antimicrobial action in the follicles and inhibits P acnes, while the antimicrobial effectiveness of hexachlorophene is limited to the skin surface.

The role of stratum corneum (SC) constituents in SC barrier properties was assessed directly in vitro in a reaggregated system. Fragments of SC from the sole of the foot (hyperplastic tissue) and from the calf (normal tissue) were reduced, separately, to individual cells and these cells were depleted of lipids by solvent extraction. Lipids taken from the cells themselves or from SC from other areas of the body were then added to the cells. None of the fractions used allowed for reaggregation of plantar SC cells, or of trypsinized calf SC cells. In contrast, calf SC cells reaggregated equally well with all lipids and formed coherent SC sheets. At equal lipid:cell ratios, however, plantar lipid-calf cell SC sheets were about three time more permeable to water than calf lipid-calf cell SC sheets. The effectiveness of the barrier function of the SC sheets was directly proportional to the amount of added lipid. We conclude that in normal SC the extractable lipids are intimately involved in cellular adhesion/dyshesion and in barrier formation.

Desquamation has been measured in the past by a counting chamber technique after corneocytes are removed from the skin surface and disaggregated in a dilute surfactant solution. However, we have found that complete corneocyte disaggregation is not always possible when these aggregates are recovered from sites where patent peeling is induced. Corneocyte counting in such instances is difficult or impossible. We have devised a method of measuring desquamation wherein the desquamating cells are determined as the total alkali-soluble protein after they are removed from the skin surface with an inert, self-hardening gel. Highly reproducible desquamation rates are obtained, characteristic of the individual subject. Using some common exfoliants, we show that pharmacologic response, observed as an increase in desquamation rate, is also an individual characteristic.

• The present study was designed to reexamine the question of the potential comedogenicity of topical sulfur. Studies were done by two different investigators in two separate institutions with groups of 12 and 40 subjects, respectively. Biopsy specimens were obtained from the occluded test sites before and after a six-week period of treatment. Each subject received a patch test of 5% sulfur in either an octoxynol 9 (Triton X-100) or a carbomer 934P (Carbopol 934P) vehicle and one of two controls consisting of the Triton X-100 vehicle or a dry patch test. We conclude that no trend or correlation was noted between the presence or absence of sulfur in the formulation and the appearance of comedones. The Triton X-100 vehicle itself appeared to be comedogenic under the experimental conditions. (Arch Dermatol114:1340-1342, 1978)

Past attempts to relate mechanical properties of the stratum corneum to its state of hydration or disease condition have been hampered by the lack of adequate in vivo methodology. With the technique described herein, viscoelastic properties of the skin surface can be measured in vivo or on excised skin in vitro. This method is sensitive enough to detect changes in the properties of the stratum corneum induced by topically applied agents or by mechanical disruption of it. The viscoelastic data suggest that the outermost layers of the stratum corneum may become dry in vivo despite their proximity to the underlying wet tissue, and that the instrument is sensitive enough to measure the changes that occur. It also appears that the in vivo behavior of the stratum corneum is similar to that of isolated stratum corneum membranes which become brittle when they are dried and supple when they are hydrated.