Pii: s0190-9622(99)70006-x

Changes in hair weight and hair count in
men with androgenetic alopecia, after
application of 5% and 2% topical minoxidil,
placebo, or no treatment
Vera H. Price, MD,a Emory Menefee, PhD,b and Paul C. Strauss, MDc San Francisco and Richmond, California, and Kalamazoo, Michigan Quantitative estimation of hair growth using hair weight and number was recorded for 120 weeks in 4groups of 9 men with androgenetic alopecia. Three double-blind groups applied either 2% or 5% minoxidilsolution, or vehicle. The fourth group, unblinded, received no treatment. Measurements of hair weight andnumber were continued for 96 weeks, when treatment (if any) was stopped, though measurements werecontinued for another 24 weeks. Although not compared statistically, the placebo and untreated groupsbehaved in a similar fashion. In contrast, the 5% and 2% minoxidil treatment groups showed a statisticallysignificant increase in mean percentage change in interval weight from baseline compared with placebo;results for number counts were usually less significant. Over 96 weeks, topical minoxidil induced andmaintained an increase in interval weight over baseline of about 30%. After treatment was stopped, hairweight and number counts for the minoxidil groups returned to about the same levels as placebo in 24weeks. (J Am Acad Dermatol 1999;41:717-21.) We previously recommended total hair surements were continued for 24 additional weeks.
weight from a defined scalp area as the pri- Concurrently, a group of men with androgenetic mary estimator for hair growth.1 The effi- alopecia received no treatment and their hair growth cacy of a hair growth–promoting agent can be estab- was compared with the treated groups over the lished in 24 weeks by comparing the total hair same 120-week period (this group was perforce not weight of hair grown in a small, carefully maintained part of the blinded study). A preliminary account of area on the scalp in subjects given either a hair part of this study was previously published in con- growth promoter or a placebo. We now extend the method to longer times, more subjects, and a widerrange of treatments. In this study, quantitative esti- mation of hair growth was recorded for 120 weeks Subject selection
for a group of men with androgenetic alopecia. Our Eligible subjects for this study were 18- to 40-year-old purpose was to compare the effect of 5% and 2% men with androgenetic alopecia as evidenced by topical minoxidil solution and placebo, in a random, frontal/parietal thinning defined by the Hamilton Scale as double-blind protocol, on both hair growth promo- type III or IV. They had to be in good health and have dark, tion and retardation of the hair loss process, using undyed hair, with no gray or white hair. Exclusion criteria total hair weights and counts. After 96 weeks, treat- included use of topical minoxidil within the previous 6 ment was stopped, although the hair growth mea- months; use of any investigational drug within the previous6 months; concomitant use of steroids, vasodilators, antihy-pertensives, calcium channel blockers, antiepileptic drugs, From the Department of Dermatology, University of California, San cytotoxic agents, “hair restorers,” or other medications that Franciscoa; Trichos Research, Richmondb; and Pharmacia & could influence hair growth; or prior participation in a top- ical minoxidil study. Pre-enrollment laboratory studies Supported by a grant from Pharmacia & Upjohn.
included a complete blood cell count with differential, uri- Accepted for publication June 24, 1999.
nalysis with microscopic examination, liver function tests, Reprint requests: Vera H. Price, MD, Department of Dermatology, University of California, San Francisco, 350 Parnassus Ave, Suite and determination of levels of lactic dehydrogenase, calci- um, phosphorus, creatinine, uric acid, blood urea nitrogen, Copyright 1999 by the American Academy of Dermatology, Inc.
serum electrolytes, thyroxine, and thyroid-stimulating hor- 16/1/100949
mone. These studies, as well as an electrocardiogram, and 718 Price, Menefee, and Strauss
fully hand clipped and collected under magnification inthe manner previously described.1 Measurement method
Hair samples were degreased in trichlorotrifluo- roethane (Freon TF) and dried. The total hair sample wasspread out on a grid and counted. The hair sample wasthen placed in the chamber of an analytical balance having0.01 mg readability. After conditioning for at least 1 hour inthe balance chamber, the ambient relative humidity wasrecorded, and the samples weighed. Sample weights werecorrected to a standard humidity of 65%.1 Weightsobtained by this method are termed interval weights todistinguish them from total (cumulative) weights. They areequivalent to growth rates (weight produced per 6-weekinterval).
Fig 1. Comparison of mean percentage change in interval
Protocol
weight per square centimeter for 4 treatment groups: 5% Following their hair clipping on the second visit, 27 minoxidil, 2% minoxidil, placebo, and untreated. Vertical subjects were assigned test solutions that were a solution line at 96 weeks marks cessation of treatment.
of either 2% minoxidil (in a vehicle of 20% vol/vol propyl-ene glycol, 60% ethanol, and water) or 5% minoxidil (in avehicle of 50% vol/vol propylene glycol, 30% ethanol, and chest x-ray if not taken in the prior 6 months, all had to have water), or the 5% vehicle solution referred to as placebo.
normal results or findings to qualify for eligibility in the The subjects were assigned the test solutions in a ran- study. Thirty-six men 24 to 40 years of age qualified for the domized, double-blind manner as follows: 9 men received study and signed an informed consent.
5% topical minoxidil solution, 8 men received 2% topicalminoxidil solution, and 10 men received placebo. They Scalp site selection and sampling frequency
were instructed to apply 1 mL of the assigned solutions A representative site was selected on the thinning with a metered dropper twice daily to the frontal/parietal frontal/parietal scalp. Hair in the designated area was care- scalp, beginning at the clipped site. Applications were fully hand clipped under magnification on the screening made with the scalp dry, spread with one fingertip, and visit (designated as week –6) and at 6-week intervals there- then allowed to dry without a hair dryer. After 96 weeks, after, for a total of 120 weeks. No treatment was given dur- treatment was stopped and the hair growth measurements ing the first 6 weeks, so that the sample collected at the were continued for 24 additional weeks. Nine additional end of this interval represented baseline growth (week 0).
men with similar scalp hair thinning were followed up con- For the men assigned to one of the treated groups, treat- currently without treatment for 120 weeks.
ment was started on the second visit (week 0) and contin- All 36 subjects were well matched in age, duration and ued for 96 weeks. After 96 weeks, treatment was stopped extent of alopecia, and original target area hair density. To and hair clippings were continued at 6-week intervals for avoid accidental hair cutting in the test site, hair cuts for 24 additional weeks. Concurrently, the group of untreated the purpose of hair styling were permissible only during men had their hair clipped with the same method every 6 the 7 days after a clipping procedure.
During the study, vital signs, medical events, and skin tolerance were monitored, and serum minoxidil levels, Marking and clipping procedure
hematology, and blood chemistries were measured.
During the screening (week –6) clipping, a template consisting of a plastic sheet with a square hole (1.34 cm2)was placed over the selected site. All hairs within the tem- plate square were pulled through it, with the help of a Thirty-three subjects completed the first 96 weeks magnifying lamp to ensure that only hair originating with- and 32 subjects the entire 120-week study. One in the square was included. The hairs were grasped and untreated subject withdrew at week 6, two treated hand clipped to about l mm in length with small straight subjects (assigned to 2% minoxidil solution and surgical scissors. Four small dots were then placed in the placebo) withdrew at week 48 because of scheduling corners of the square with a fine ballpoint pen. After the problems, and one treated subject (assigned to 2% template was removed, the 4 corners were permanently minoxidil solution) dropped out at week 96 because marked using ink and the Spalding and Rodgers marking he did not wish to stop treatment. Occasionally, a On subsequent visits at 6-week intervals, the plastic subject was unable to appear on the exact scheduled template was laid in exact correspondence with the per- date for clipping. To facilitate statistical analysis, the manent markings, and the hair in the marked square care- measured weight from these erratic intervals was Price, Menefee, and Strauss 719
Fig 2. Comparison of mean percentage change in num-
Fig 3. Comparison of the mean percentage change in
ber per square centimeter for 4 treatment groups: 5% excess cumulative weight for 4 treatment groups: 5% minoxidil, 2% minoxidil, placebo, and untreated. Vertical minoxidil, 2% minoxidil, placebo, and untreated. Vertical line at 96 weeks marks cessation of treatment.
line at 96 weeks marks cessation of treatment.
adjusted by a multiplying factor of 42/D, where D is Another representation, which we have called the actual number of days in the interval. This adjust- excess cumulative weight, has been found to be use- ment assumes that the growth rate remains constant ful for discriminating among different treatments. It during the short period needing correction. Interval is defined as the difference between the actual weights used in this article have been adjusted by cumulative mean weight and the hypothetical cumu- this method when necessary. No correction was lative weight that would accrue if growth continued made to number counts from subjects who did not at the same rate as during the baseline pretreatment return at an exact 6-week interval. The numbers of period (from week –6 to week 0). Thus excess cumu- subjects in the calculation groups were as follows: 7 lative weight represents the aggregate change in subjects in the 2% group (6 after week 96), 9 subjects weight, if any, caused by treatment. Expressed differ- in the 5% group, 9 subjects in the placebo group, ently, the excess cumulative weight reflects the total and 8 subjects in the untreated group.
cumulative hair protein production induced by treat- Results of the measurements of interval weights ment. In number counts, the equivalent of a cumu- and number counts are summarized in Figs 1 and 2, lative function is simply the baseline value subtract- respectively. Each point on these figures represents ed from the count at a particular time. The mean the mean percentage change from baseline of all percent change in excess cumulative weight is illus- subjects in the designated group (2% and 5% minox- trated in Fig 3 for the 4 treatment groups.
idil treatments, placebo, and untreated). Treatment,if any, was stopped at week 96 (indicated in the fig- DISCUSSION
ures by a vertical line). Percentage changes are plot- For statistical comparison, the 3 treatments were ted rather than the primary measurements of inter- considered as a group, and a one-sided analysis of val weight and number count to remove baseline variance test was used to determine whether there is variation and more accurately isolate effects caused significant difference among any of the 3 treatments by treatment. The primary measurements are not (overall P value < .05). In this test, it was found that useful for statistical comparison owing to differences all trials up to week 96 showed significant differences in their baseline values at week 0. Over all subjects, for 2 of the 3 measurement variables: mean percent- baseline interval weights ranged from 2.9 to 15.0 age weight change and mean percentage change in mg/cm2, with a standard deviation of 40% and base- excess cumulative weight. However, for mean per- line number counts ranged from 79 to 251 per centage number change, about one third of the trials square centimeter, with a standard deviation of 21%.
showed no significant difference among the 3 treat- This variability is a reflection of the wide range of ment groups (5% and 2% minoxidil, and placebo); normal growth among a sampling of subjects and is these trials are shown as italicized numbers in Table approximately maintained throughout subsequent I. We interpret this decreased significance in mean percentage number change (as contrasted with the 720 Price, Menefee, and Strauss
Table I. P values from Fisher least significant difference comparisons of 2%-5% (2-5), 2%-placebo (2-P), and 5%-
placebo (5-P)*
Mean percentage
Mean percentage
Mean percentage
weight change
number change
excess cumulative weight change
*0 represents P < .0005; (P > .05), nonsignificant. Analysis of variance intergroup tests are italicized.
weight variables) to the large fluctuation in the num- Mean percentage changes in interval weights ber of small hairs during the growth changes from baseline are shown in Fig 1. The placebo and induced by minoxidil. The effect of small hairs is not untreated groups appear to behave similarly, show- as pronounced in weight measurements. This pro- ing a steady decrease in hair weight from baseline vides confirmation of our suggestion that weight over the 120 weeks. This decrease can be taken as measurements offer a more reliable estimation of the “normal” hair loss for this group of subjects with androgenetic alopecia and amounts to about a 6% The Fisher least significant difference test was decrease in weight per year. The 2% and 5% minoxi- used to determine which of the 3 treatment groups dil groups appear to decrease with nearly the same show significantly different means. P values from this average downward slope, once the peak rate of growth has been passed. The treatments appear to For the two weight variables (mean percentage induce a consistent increased growth offset (above weight change and mean percentage excess cumula- placebo or untreated groups) of roughly 25% for the tive weight change), differences between either the 2% minoxidil treatment and 35% for the 5% minoxi- 2% and 5% treatment levels and placebo were gen- dil treatment, an average increase of about 30%, erally significant (P ≤ .05) after only 6 weeks of treat- maintained during the 96 weeks of treatment. These ment. The incremental increase in hair growth over growth offsets represent a long-term retardation of placebo seen after week 6 was maintained through the hair loss process by both 5% and 2% topical the 96 weeks of treatment for both the weight vari- ables. Comparison of the 2% minoxidil treatment Mean percentage changes in number counts from with placebo was not generally significant for the baseline are shown in Fig 2. Despite what appears as mean percentage change in number counts; howev- a somewhat erratic response, the fluctuations in er, the 5% minoxidil treatment showed a consider- number counts for 5% and 2% minoxidil (apparently ably greater significant difference in number counts greater than those for weights) reflect a distinct over placebo, though not at all treatment times.
series of events that occur after the onset of treat- Differences between the 2% and 5% treatments ment. We hypothesize that the first stage of regrowth themselves were not statistically significant for appears to involve enlargement of a number of weight changes or number change (P > .05), though miniaturized hairs, which also have shortened a difference appears visually apparent in Figs 1-3.
growth cycles, as well as the probable nudging of Price, Menefee, and Strauss 721
many older anagen hairs into telogen. Hence the paring Fig 3 with Figs 1 and 2, but also from the sta- first indication of treatment efficacy is a large tistical comparisons in Table I, where P values reach increase in total hair count within 12 weeks. This lower levels at earlier treatment times for excess spurt is particularly evident with 5% minoxidil, an cumulative weight changes than for either weight or effect seen with both interval weights and number number count changes. This sharper discrimination counts. Because the cycles are mostly still short, makes the excess cumulative weight useful for rapid these “new” anagen hairs enter telogen and fall out quickly, to be replaced with another wave of hairs After treatment was stopped at week 96, the 5% that have somewhat longer growth cycles. This and 2% minoxidil groups showed a rapid loss of hair process repeats, and no strong decline seems evi- weight and decreased hair counts. Vertical lines dent through 96 weeks, although the long-term drawn at week 96 in Figs 1-3 indicate when treat- number counts should eventually decrease. A “place- ment was stopped. By 24 weeks after treatment had bo effect” appears to occur more markedly for num- been stopped, the weight and number counts of the ber counts than for weights, for reasons at present treated groups decreased to become similar to those of the placebo and untreated groups, showing the If we can ignore the fluctuations, the changes in growth offset produced by topical minoxidil. This number counts from baseline of the treated sub- loss of treatment-stimulated hair growth is expected jects generally parallel the changes in weight. We since treatment does not alter the underlying genet- believe that the weight measurements have more ic predisposition for androgenetic alopecia.
reliability than number counts when assessing hair This study demonstrates that 5% and 2% topical growth, at least in terms of increased hair protein minoxidil promote hair growth and retard the hair production. Counts of the smallest hairs are subject loss process over 96 weeks, with 5% topical minoxi- to unavoidable uncertainty, though they contribute dil having the greater efficacy. Although the interval little to the total hair weight. Furthermore, fluctua- hair weight eventually began to decrease with time, tions in numbers of small anagen hairs with short the minoxidil treatment maintained an increased growth cycles are not as strongly reflected in the rate of hair weight (protein) production, over that of placebo or untreated subjects, of about 25% more Excess cumulative weight is shown in Fig 3, as for the 2% minoxidil treatment and about 35% more percentage change from the extrapolated baseline for the 5% minoxidil treatment and averaging about cumulative weight. Fluctuation appears smaller than 30% during the 96-week treatment period.
that of the interval weight, a characteristic of cumu-lative functions. Because earlier interval weight data We thank The Upjohn Company for continued support.
are carried along in the excess weight function, We are grateful to Cathy Kavanagh, Andrea Menefee, and changes or fluctuations in later interval weights tend Leta Regezi for technical assistance.
to be somewhat masked. This behavior is also appar-ent when treatment is stopped at 96 weeks. The REFERENCES
1. Price VH, Menefee E. Quantitative estimation of hair growth. I.
excess cumulative weight decreases more gradually Androgenetic alopecia in women: effect of minoxidil. J Invest during the 24 weeks after stopping of treatment than do either the weights or numbers in Figs 1 and 2.
2. Price VH, Menefee E. Quantitative estimation of hair growth: For discriminating among different treatments, comparative changes in weight and hair count with 5% and 2% especially at early times, the excess cumulative minoxidil, placebo and no treatment. In: Van Neste D, RandallVA, editors. Hair research for the next millenium. Amsterdam: weight seems to offer a clearer separation of treat- ment effects than either interval weights or numbercounts. This is apparent not only from visually com-

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