Dandruff is a common dermatologic condition resulting in scalp symptoms such as flaking, crusting, erythema, itching, and hair breakage. It afflicts both males and females, but is more problematic in females due to hair length and the need to maintain the cosmetic value of the hair. Since sebum and scalp scale are well-known requirements for the initiation of dandruff, traditional dandruff shampoos usually focus on delivering active anti-dandruff ingredients and thorough removal of scale and sebum. These shampoos indeed improve the patient perception of dandruff, but often at the expense of hair beauty, resulting in decreased patient shampoo compliance. Furthermore, dandruff is a chronic, relapsing dermatologic condition related to fungal colonization of the scalp by Malassezia that requires continued use of the medicated shampoo. The recognition that hair cosmesis must be maintained while at the same time treating dandruff has led to the next generation of dandruff shampoos combining over-the-counter technologies for minimizing fungal colonization of the scalp and synthetic detergents to remove excess scalp sebum with silicone-based conditioners to maximize hair beauty. This study evaluated the efficacy of a novel 1% pyrithione zinc conditioning shampoo with silicone based conditioner as compared to a 2% ketoconazole shampoo with minimal conditioning in improving hair condition and cosmetic acceptance.
Results
Both shampoos were well tolerated by all subjects. All subjects completed the study with no adverse events.
Both the 1% pyrithione zinc conditioning shampoo and the 2% ketoconazole shampoo produced improvement in dandruff as assessed by the dermatologist investigator at the end of week 1 (Figure 1 and Figure 2), with directional improvement in flake reduction favoring the conditioning 1% zinc pyrithione shampoo (Table I). Both shampoos continued to improve dandruff symptoms at weeks 2 and 4 with no statistically significant differences (Table II). Comparative dandruff assessments, however, could not be made at week 2 or 4 due to the cross-over design subjects had used both shampoo formulations, and therefore no conclusion was drawn as to which product was effecting dandruff mitigation.
In all, 75% of the subjects preferred the 1% pyrithione zinc conditioning shampoo to the 2% ketoconazole shampoo at the end of study week 2. This was found to be highly statistically significant using a chi-square statistical analysis (p=0.0016).
The cosmetic benefits were evaluated by the dermatologist investigator and consisted of a visual assessment of the ability of the study shampoos to control frizzy/flyaway hair, ease of hair combing, and hair smoothness. A non-parametric Wilcoxon Signed Rank Test was used for the statistical analysis. After one week of use, the 1% pyrithione zinc conditioning shampoo was significantly better than the 2% ketoconazole shampoo at improving hair smoothness (p=0.035) and hair combing (p=0.044). During the second cross-over study week, the 1% pyrithione zinc conditioning shampoo was significantly better than the 2% ketoconazole shampoo at improving hair frizz/flyaway (p=0.0053) (Table III, Figure 3) and hair smoothness (p=0.0041) (Table IV, Figure 4). At the study conclusion following 2-wk use of the subject-selected shampoo, hair-combing ease was directionally better for the 1% pyrithione zinc conditioning shampoo (p=0.055). At all time points, the conditioning 1% pyrithione zinc shampoo was found to aid various aspects of hair cosmesis, even though there may have been some carryover effect from subject exposure to both study products.
Discussion
This study evaluated a frequently overlooked aspect of dandruff treatment, which is hair comesis (Lochhead, 2001). Physicians commonly assess the therapeutic efficacy of a shampoo based upon its ability to decrease scalp scaling and itching, the most bothersome patient symptoms associated with dandruff. But dandruff is a relapsing, recurrent disease associated with fungal colonization of the scalp that requires the continuous use of dandruff shampoos to maintain remission. Over time, an anti-fungal shampoo that simply addresses the scalp sebum and scale removal aspects of dandruff (Harding et al, 2002) will degrade the cosmetic value of the hair. Excessive removal of sebum results in hair that is dry and subject to static electricity, predisposing to the frizzy/flyaway appearance of the hair. A shampoo that contains detergents and therapeutic agents to treat the various aspects of dandruff can be formulated with appropriate conditioners, such as silicones, fatty alcohols, and quaternium compounds, to minimize static electricity and decrease hair frizz. This improves hair manageability and facilitates easier styling.
Frequent shampooing and daily wear and tear also damage the hair cuticle such that the cuticular scales no longer tightly overlap in an orderly fashion. This disruption of the cuticular scales creates hair surface irregularities, which decreases the smoothness of the hair shaft (Rook, 1976). Decreased smoothness means less light reflection and decreased hair luster. Patients equate shiny hair with healthy hair, which is actually an assessment of the state of the cuticle (Starch, 1999). Silicone-based conditioners, such as dimethicone, are one of the newest agents that aid in smoothing the cuticle and increasing hair smoothness and luster. The silicone is left behind following water rinsing of the shampoo as a thin coating over each individual hair shaft to fill in visible defects in the hair cuticle.
Probably the most important aspect of hair cosmesis is combing ease. Increased hair friction snags the hair as the comb is drawn for grooming purposes, resulting in hair breakage. This is the most common cause of significant hair loss in normal patients, patients with dandruff, and patients afflicted with female pattern hair loss. Combability of the hair can be increased by smoothing the cuticle and coating each individual hair shaft with an agent to decrease friction. Silicone fulfills this need (Sun et al, 2002). Silicone is a lubricant that is known to reduce friction in a variety of industrial and cosmetic applications. This same technology with lower viscosity has been adapted to the hair care industry. Silicone is an inert, hypoallergenic, noncomedogenic, nonacnegenic substance that does not support the growth of fungal organisms that induce dandruff (Ruiz et al, 1998). Yet, it does not leave the hair appearing or feeling greasy when properly formulated (Hunting, 1988).
The 1% pyrithione zinc conditioning shampoo studied in this research contained silicone technology designed to improve hair cosmesis while treating dandruff (Warner et al, 2001). This is a new concept, since previous dandruff shampoo technology has focused only on the need to remove sebum while depositing an active agent on the scalp for dandruff treatment. The two shampoos evaluated represented different formulations. The 2% ketoconazole shampoo provided good cleaning but few conditioners (only laurdimonium-hydrolyzed animal collagen). It is currently utilized by dermatologists for dandruff treatment; however, as this study demonstrated, compliance may be poor due to its inability to improve hair cosmesis. The 1% pyrithione zinc formula contained a combination of conditioning ingredients (dimethicone, cetyl alcohol, polyquaternium 10) commonly found in cosmetic shampoos. 75% of the female subjects enrolled in the study preferred the 1% pyrithione zinc conditioning shampoo, since it not only treated the signs and symptoms of dandruff but also improved the appearance and feel of the hair. This subject perception was also confirmed by the dermatologist investigator who noted improvements at various time points in hair-combing ease, hair smoothness, and hair frizz/flyaway.
This study demonstrates the need to consider both efficacy and hair cosmesis when selecting maintenance shampoos for dandruff patients. A quality dandruff shampoo must possess both characteristics to improve patient compliance. Compliance is an important part of dandruff treatment, since the disease is chronic and relapsing. A novel 1% pyrithione zinc conditioning shampoo was found to improve hair cosmesis and dandruff symptoms in a female dandruff population.
Materials and Methods
Forty females between the ages of 18 and 50 with mild to moderate dandruff as judged by the dermatologist investigator were enrolled in this Institutional Review Board (Schulman Institutional Review Board, Cincinnati, Ohio) approved 5-wk double-blind cross-over study to evaluate the effect of two different shampoos on scalp dandruff, hair condition, and subject compliance. Subjects were required to have hair of sufficient length such that it could be combed. All subjects underwent a 1-wk washout period with a basic non-conditioning cleansing shampoo (Pantene Clarifying Shampoo, Procter & Gamble, Cincinnati, Ohio) to standardize hair condition prior to study initiation. No conditioners or other shampoos were allowed during the washout period, and subjects were asked to shampoo a minimum of two times weekly. Subjects were then randomized to receive one of the two study shampoos to use for one week such that no statistical difference in dandruff severity was noted between cohorts at baseline (refer to Figure 1). Twenty subjects received the novel conditioning 1% pyrithione zinc conditioning shampoo and the remaining 20 subjects received a 2% ketoconazole shampoo. At the end of one week, subjects crossed over to use the other study shampoo for an additional week. At the end of the second study week, subjects were asked to pick their preferred shampoo for continued use during the last two weeks of the study.
Assessments were collected in the form of scalp photographs, subject assessments, and investigator assessments at baseline, week 1, week 2, and week 4. The investigator assessed scalp scale, erythema, crusting, and overall impression. She also assessed ease of combing, hair smoothness, and hair frizz/flyaway at each time point.
References
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- Rook, A: The clinical importance of "weathering" in human hair. Br J Dermatol 95: 111–112, 1976
- Ruiz, M, Hernandez, A, Llacer, J, Gallardo, V: Silicone chemistry. Cosmet Toilet 113: 56–72, 1998
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- Warner, RR, Schwartz, JR, Boissy, Y, et al: Dandruff has an altered stratum corneum ultrastructure that is improved with zinc pyrithione shampoo. J Am Acad Dermatol 45: 897–903, 2001
Acknowledgements
I would like to acknowledge my research staff who assisted me in conducting this study: Jennifer Stiles, Vickie Ellis, Marty McCarn, Christin Foster, and Patti Yeats.
