Thin-layer chromatography of pyrithiones

Seymour, Mark Donovan; Bailey, D. L.

doi:10.1016/s0021-9673(00)82540-6

Cited by 17 publications

(1 citation statement)

References 9 publications

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“…PTZ, like all metal-organic complexes when in a liquid medium, is governed by an equilibrium between the associated zinc-pyrithione complex (i.e., PTZ) and dissociated zinc and pyrithione components (Seymour and Bailey, 1981). Since PTZ is the bio-active species, dissociation has negative consequences on efficacy.…”

Section: Abbreviation: Ptz Pyrithione Zincmentioning

confidence: 99%

Product Pharmacology and Medical Actives in Achieving Therapeutic Benefits

Schwartz

2005

Journal of Investigative Dermatology Symposium Proceedings

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Scalp skin is physiologically very similar to non-palmoplantar skin of the rest of the body, except for the very high concentration of sebaceous glands (Giacometti, 1965). The scalp environment, however, is much different in being covered by a thick fabric of hair. There are about 250 hair fibers per cm 2 , which results, for a typical individual, in a hair surface area of 50,000 cm 2 relative to the scalp surface area of 600 cm 2 . Together, these parameters indicate the relative inaccessibility of the scalp surface to targeted delivery of actives; relatively low delivery efficiency in this protected environment is an inherent challenge to achieving therapeutic benefits. This is especially true of the most patientfriendly format-shampoos-since a rinsing step is involved and the product cannot interfere with achieving desired hair cosmetic benefits (compliance decreases dramatically if hair cosmetics are poor). This places a large demand on actives with high activity since delivery efficiency will be inherently low as well as development of product pharmacologies that maximize the benefit of the actives employed. This situation will be exemplified for the most common scalp care therapeutic products, those designed to treat dandruff and seborrheic dermatitis (D/SD) utilizing anti-fungal actives to reduce Malassezia content on the scalp.The most common anti-fungal materials used in D/SD scalp therapies include those based on rational chemical design principles (ketoconazole, climbazole, pyrithione zinc (PTZ), piroctone olamine and ciclopirox olamine) as well as materials originating from indeterminate histories (selenium sulfide, sulfur, coal tar, and salicylic acid). Because of the aforementioned demands on activity due to challenging delivery, only those materials with high intrinsic anti-fungal activity should be considered as the basis for therapeutic products. Based on measurement of minimal inhibitory concentrations (MIC) against Malassezia, the most potent materials from this group are pyrithione zinc, selenium sulfide, climbazole, and ketoconazole (VanGerven and Odds, 1995; Schmid and Rü hl-Hö rster, 1996).For a formulated therapeutic product to be effective, a potent active is a necessary but insufficient condition to achieve activity. The way the active is delivered to the scalp from the product formula, i.e., the product pharmacology, is at least as strong a determinant of in-use activity as the intrinsic active potency. For example, a comparison of clinical flake-reduction efficacy of a variety 1% PTZ-based D/ SD shampoo products demonstrates a wide range of magnitude of therapeutic benefits. Much of this variation is likely due to the varying efficiency of delivery of PTZ, a particulate active, to the scalp surface. Particulate PTZ delivery will be affected by the physical size and shape of the particle (as well as other formulation parameters, which will not be covered further here). Particles which are flat cover the scalp surface more efficiently than those that are not. The particle size is also cr...

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Section: Abbreviation: Ptz Pyrithione Zincmentioning

confidence: 99%

Product Pharmacology and Medical Actives in Achieving Therapeutic Benefits

Schwartz

2005

Journal of Investigative Dermatology Symposium Proceedings

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Determination of Zinc Pyrithione in Hair Care Products on Metal Oxides Modified Carbon Electrodes

Wang

2000

Electroanalysis

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A simple electroanalytical method for the determination of zinc pyrithione (ZPT) in commercial cosmetic products has been developed using a metal oxide modi®ed carbon paste electrode. Ingredients in the cosmetic products did not show any interference in the determination of zinc pyrithione. The electrocatalytic behavior in relation to the properties of metal oxides and the mechanism of the oxidation process was investigated using cyclic voltammetry, linear sweep voltammetry , chronoamperometry. and differential pulse voltammetry. Comparison with results obtained from high performance liquid chromatography shows good agreement. The zinc and sodium pyrithiones (Omadine) are broad±spec-tum antimicrobial agents, effective against both bacteria and fungi [1]. They were used as cosmetic preservatives in the late 1960's and the Procter and Gamble Co. discovered the antidandruff properties of zinc pyrithione (zinc 2-pyridinethiol-Noxide or ZPT). ZPT has been established as one of the most effective antidandruff ingredients for use in shampoo, conditioner, rinse and hairdressing formulations through various clinical studies [2]. In 1981 the Food and Drug Administration (FDA) reported that 29 formulations registered with the agency contained ZPT and 7 contained the sodium salt [3]. The Economic Community (EEC) Council Directive allows ZPT to be used in cosmetic products as a preservative in shampoos and conditioners as a antidandruff agent at a maximum concentration of 0.5 % and 1.0 %, respectively [4]. The toxicity of pyrithione salts by various routes of exposure has been studied extensively in several species of animals and has been described previously [5±16].Several analytical methods for pyrithiones have appeared in the literature [17±30]. In general, they involve titration with Ti(III) ion [17], thin-layer chromatography [4, 18±19], highperformance liquid chromatography [20±26] and polarography [27±30] procedures. Titrimetric methods suffer from a lack of selectivity for pyrthione and interferences in hair care products. Quantitative TLC analysis requires the use of a spectrodensitometry and ZPT decomposes in sunlight on TLC plates. Sodium pyrithione is dif®cult to quantitate by means of TLC because it reacts with metals in the TLC plate. The normal-phase HPLC conditions in the on-line Cu(II) complex formation technique can damage the analytical column in time. The direct reverse-phase HPLC analysis of ZPT is dif®cult owing to the interaction with the reverse-phase packing materials or stainlesssteel compounds of the liquid chromatography even if Zn(II) is added to the mobile phase.Although polarography offers greater speci®city it is limited to the determination of 2-pyridinethiol and 2-pyridinethiol-N-oxide. ZPT is substantially insoluble in water and is present in aqueousbased products as a dispersion of ®ne solid particles. However, ZPT is soluble in 1 M hydrochloric acid or alkaline solution. ZPT dissolved in 1 M hydrochloric acid showed a degradation of 10 % immediately, 25 % after 24 hours and 93 % af...

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Degradation of Alternative Biocides in the Aquatic Environment

Harino

Langston

Ecotoxicology of Antifouling Biocides

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Thin-layer chromatography of pyrithiones

Cited by 17 publications

References 9 publications

Product Pharmacology and Medical Actives in Achieving Therapeutic Benefits

Product Pharmacology and Medical Actives in Achieving Therapeutic Benefits

Determination of Zinc Pyrithione in Hair Care Products on Metal Oxides Modified Carbon Electrodes

Degradation of Alternative Biocides in the Aquatic Environment

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