An animal model for screening topical and systemic drugs for potential use in the treatment of psoriasis.

A new hairless mouse model using ultraviolet light to stimulate increased epidermal cell turnover and hyperplasia and thus simulate psoriasis has been designed so that drugs may be tested both topically and systemically for possible therapeutic value in this disease. Two methods of determining drug antimitotic activity have been used, the mitotic index and the extraction of epidermal DNA and the determination of the radioactivity of the sample. Results show that 2% 5-fluorouracil in propylene glycol and 2% nitrogen mustard in water topically and cyclophosphamide systemically, which are drugs known to be effective in psoriasis, significantly reduce the mitotic index. DNA synthesis is similarly decreased by the latter two drugs. The effect of the topical agents is shown to be local and not systemic. Cyclophosphamide, which is ineffective topically in psoriasis, is ineffective in the model.

Effects of topical prostaglandin E analogue on normal hairless mouse epidermal DNA synthesis.

The in vivo topical effects of a synthetic analogue of prostaglandin E2 (15(S)-15-methyl PGE2 methyl ester [PGE2 analogue]), have been studied on the epidermis of hairless mice. One microgram of the PGE2 analogue increased DNA synthesis significantly by 5 hr, a maximum increase of 390% was reached by 12 hr, and DNA synthesis returned to control levels by 24 hr. Twenty micrograms of the PGE2 analogue reduced epidermal DNA synthesis for 12 hr after application, DNA synthesis was increased at 24 hr, returning to control levels by 48 hr. One hundred micrograms of topical PGE2 had no significant effect on epidermal DNA synthesis over 48 hr, but 1 mug of intradermal PGE2 increased DNA synthesis by 160% at 24 hr. These results suggest that topical 15(S)-15-methyl PGE2 methyl ester is biologically active compared with PGE2.

Laboratory induction and clinical occurrence of combined clindamycin and erythromycin resistance in Corynebacterium acnes.

Corynebacterium acnes strains cross-resistant to clindamycin and erythromycin were observed following long-term selection or mutagenic treatment in the laboratory. Similar strains were found among clinical isolates from patients using clindamycin or erythromycin topically in the treatment of acne vulgaris. Clindamycin resistance was never observed in the absence of resistance to macrolides or other lincosaminides. It is suggested that this resistance may result from an alteration of the 50S ribosomal subunit.

Ciclopirox olamine lotion 1%: bioequivalence to ciclopirox olamine cream 1% and clinical efficacy in tinea pedis.

Studies were conducted to assess the bioequivalence of a new antimycotic formulation, ciclopirox olamine lotion 1%, to an established compound, ciclopirox olamine cream 1%. Results of in vitro studies, using skin samples from human cadavers and domestic pigs, demonstrated that the two formulations equally penetrate all layers of the stratum corneum and inhibit the growth of Trichophyton mentagrophytes and Candida albicans. In vivo studies in guinea pigs and in human volunteers demonstrated the comparable therapeutic efficacy of the lotion and the cream in experimental trichophytosis. In addition, a multicenter, double-blind clinical trial was undertaken to compare ciclopirox olamine lotion 1% with the vehicle alone in the treatment of patients with tinea pedis. Patients with plantar, interdigital, or vesicular tinea pedis were enrolled in the studies. Patients were treated for 28 days. Clinical and mycological responses were determined during treatment and two weeks posttreatment. Ciclopirox olamine lotion 1% was found to be significantly more effective than its vehicle in the treatment of patients with common tinea pedis. Minor localized side effects (pruritus, burning sensation) were reported in 2% of 89 patients treated with ciclopirox olamine lotion 1%. The results demonstrate the bioequivalence of ciclopirox olamine lotion 1% and ciclopirox olamine cream 1% and confirm the clinical effectiveness and safety of the lotion in the treatment of tinea pedis, a generally recalcitrant fungal infection. It is concluded that ciclopirox olamine lotion 1% can be used as an alternative to ciclopirox olamine cream 1% for treatment of tinea pedis, tinea versicolor, tinea cruris, tinea corporis, and cutaneous candidiasis when the convenience and/or cosmetic elegance of a lotion is desired.

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.

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.

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.

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.

Dermatitis from purified sea algae toxin (debromoaplysiatoxin).

Cutaneous inflammation was induced by debromoaplysiatoxin, a purified toxin extracted from Lyngbya majuscula Gomont. This alga causes a seaweed dermatitis that occurs in persons who have swum off the coast of Oahu in Hawaii. By topical application, the toxin was found to produce an irritant pustular folliculitis in humans and to cause a severe cutaneous inflammatory reaction in the rabbit and in hairless mice.

Tachyphylaxis to the action of topically applied corticosteroids.

A previously unrecognized pharmacological event, acute tolerance to the vasoconstrictive action of topically applied glucocorticosteroids, has been discovered in human skin. Thus, potent topical glucocorticosteroids will cause vasoconstriction when first applied to human skin but with subsequent applications the production of vasoconstriction rapidly diminishes. However, after a rest period of a few days, the same initial vasoconstrictive effect may be produced again, but this will also disappear if the steroid is again continued topically. These observations have important applications to optimum timing in the clinical topical use of glucocorticosteroids for maximum therapeutic advantage.

Topically applied antibiotics in acne vulgaris: clinical response and suppression of Corynebacterium acnes in open comedones.

Topical antibiotics were used on patients with acne vulgaris. Corynebacterium acnes organisms from open comedones were quantitated during treatment, and the progress of the disease was evaluated. Clindamycin lotion completely suppressed the growth of C acnes organisms, whereas erythromycin and tetracycline did not depress the C acnes counts. Taken as a group, these antibiotics gave a substantial improvement of the disease on the treated side as compared with paired untreated sides of the face and back.

Inhibition of induction of human contact sensitization by topical glucocorticosteroids.

Ten healthy human volunteers were exposed to a primary sensitizing dose of 1 mg dinitrochlorobenzene (DNCB) by an open topical technique within an area that had been pretreated with a potent topical glucocorticosteroid compound. Quantitative elicitation testing was performed on the opposite side by an open patch test technique two weeks after the sensitizing application. One (10%) of the ten subjects became sensitized. A matched control group of ten subjects was similarly sensitized without steroid treatment. Eight (80%) of the ten became sensitized. One month later, five of the eight test subjects in whom sensitization had been prevented were retested in an identical fashion without steroid pretreatment, to determine if any degree of tolerance had been induced. All five subjects became sensitized. Topical glucocorticosteroids inhibited the development of sensitization to topically applied DNCB. Tolerance was not induced by this single process.

Crude coal tar plus near ultraviolet light suppresses DNA synthesis in epidermis.

Crude coal tar and a refined product, when they are combined with near ultraviolet (UV) light (UVA, 320-400 nm), depress DNA synthesis in vivo in normal and proliferating skin of the hairless mouse. Near ultraviolet light alone does not interfere with DNA synthesis, but coal tar without UVA does have an inhibitory effect on DNA synthesis of normal skin. This effect of coal tar without UVA is not as great as the effect of the combination of UVA and coal tar. Between 0.9 and 1.6 joules/sq cm of UVA are required for its biologic effect on DNA synthesis in coal-tar-treated skin.

Topical drug effects on normal and proliferating epidermal cell models.

The effects of 28 different antiproliferative agents applied topically to normal and hyperproliferative hairless mouse skin were studied. Epidermal cell hyperproliferation was induced by an essential fatty acid-deficient diet or by irradiation with short-wavelength ultraviolet (UV) energy. Epidermal DNA synthesis was measured by hydroxyapatite column chromatography. We compared the effects of these drugs used on normal and hyperproliferative hairless mouse skin with clinical responses in patients with psoriasis treated using the same topical preparations. For most of the drugs tested, the normal and essential fatty acid-deficient mouse model effects showed a good correlation with clinical responses seen in treated patients with psoriasis. The short-wavelength UV energy-treated mouse model effects showed a poorer clinical correlation, perhaps partially caused by wide variations in DNA synthetic rates encountered in the epidermis in this model.

Anemia of azaribine in the treatment of psoriasis.

Azaribine is an effective agent in the treatment of psoriasis. In this investigation the extent of clinical dermatologic remission appeared to correlate with the degree of metabolic block induced by 6-azauridylic acid, as quantitated by the urinary excretion of orotic acid and orotidine, and the development of anemia. Following azaribine therapy there was a coordinate rise of the specific activities of erythrocyte orotate phosphoribosyltransferase and orotidine-5'-monophosphate decarboxylase. There was no correlation between the pretreatment activity of these enzymes and the clinical response to azaribine. The anemia of azaribine therapy was mile and of a megaloblastic type. Uridine effectively corrected the azaribine-induced anemia, but led to exacerbation of the patients' psoriasis. Following uridine therapy there was a reduction in the urinary excretion of orotic acid and orotidine, presumable reflecting end-product inhibition or repression of the first steps of a repeated pyrimidine biosynthesis.

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.

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.

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.

Topical antibiotic therapy of acne: laboratory investigation of vehicles, various antibiotics, and stability characteristics.

A new vehicle preparation has proved effective in enhancing the penetration of antibiotics. The vehicle seems to maintain stability of the incorporated antibiotic.

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.