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Topical Products for Hair Regrowth
Vol. 28, No. 1, 2016 65
Received April 7, 2015, Revised May 6, 2015, Accepted for
publication May 26, 2015
Corresponding author: Pompei Bolfa, Department of Biomedical
Sciences, Ross University School of Veterinary Medicine, PO Box 334,
Basseterre, St. Kitts, West Indies. Tel: 1-732-898-0175, Fax: 1-869-
465-1203, E-mail: pompeibolfa@gmail.com
T
his is an Open Access article distributed under the terms of the
Creative Commons Attribution Non-Commercial License (http:/
/
creativecommons.org/licenses/by-nc/4.0) which permits unrestricted
non-commercial use, distribution, and reproduction in any medium,
provided the original work is properly cited.
Ann Dermatol Vol. 28, No. 1, 2016 http://dx.doi.org/10.5021/ad.2016.28.1.65
ORIGINAL ARTICLE
Topical Products for Human Hair Regeneration:
A Comparative Study on an Animal Model
Meda Sandra Orasan1, Pompei Bolfa2,3, Andrei Coneac4, Adriana Muresan5, Carmen Mihu5
1Department of Pathophysiology, Physiological Sciences Division, Iuliu Ha
ţ
ieganu University of Medicine and Pharmacy, Cluj-Napoca,
Romania, 2Department of Biomedical Sciences, Ross University School of Veterinary Medicine, Basseterre, St. Kitts, West Indies, 3Department
of Pathology, University of Agricultural Sciences and Veterinary Medicine, 4Department of Histology, Morphological Sciences Division,
5Department of Department of Histology, Physiological Sciences Division, Iuliu Ha
ţ
ieganu University of Medicine and Pharmacy,
Cluj-Napoca, Romania
Background: Hair loss and hair growth is the subject of tre-
mendous amount of research. Objective: This study inves-
tigated the efficacy of three chemical treatments used in hu-
mans for hair loss, using a rat model of hair regrowth. The
products tested were 2% minoxidil, Hairgrow (Dar-Al-Dawa
Pharma), Aminexil, Dercos (Vichy Laboratoires), and
Kerium, Anti-chute (La Roche-Posay). Methods: Thirty-two
adult female Wistar-Bratislava rats were assigned to 4 groups.
Two rectangular areas (2×4 cm) were shaved on either sides
of the mid dorsal line (left side - control; right side - test area).
Group I was treated topically with 2% minoxidil, group II
with Aminexil, and group III with Kerium. Each rat received
0.3 ml of substance applied topically to the shaved dorsal
skin every day for 28 days. Rats in group IV served as sham
controls receiving no treatment. Hair regrowth was eval-
uated by trichoscopy (with a dermatoscope), grown hair
weight (from a surface area of 1 cm2), and histopathological
examination for skin thickness, follicle count, and percent-
age of anagen induction (morphometric assessment). Results:
Treatment with 2% minoxidil significantly induced hair re-
growth as assessed by trichoscopy, hair weight examination,
and morphometric evaluation. Hair weight examination and
morphometric assessment demonstrated the lowest hair
growth effect with Aminexil among the tested products.
Treatment with Kerium was found to significantly induce
hair regrowth (
p
＜0.05 as compared to the control group).
Conclusion: Our study demonstrates that hair regrowth effi-
cacy of products recommended for human use is not similar
when tested on an animal model. (Ann Dermatol 28(1) 65∼
73, 2016)
-Keywords-
Hair regrowth, Rat model, Topical therapy
INTRODUCTION
Society places considerable emphasis on external appear-
ance, of which, hair is an important component. Scientists
and dermatologists claim that hair has an important con-
tribution to the overall appearance of the human body1,2.
Hair loss, although a natural part of the aging process, is
often a cause for concern. The profound symbolic and
psychosocial importance attached to hair is reflected by
the anxiety and distress resulting from its loss3. Cash and
colleagues4 assessed the psychological effects of hair loss
on women by comparing them with balding men and fe-
male control subjects. They confirmed the potentially ad-
verse psychosocial sequelae of this common dermato-
logical condition.
Hair loss and thinning continue to remain common der-
matological complaints despite the introduction of many
treatment alternatives. Research, aimed at new therapies
to prevent hair loss and enhance hair growth, is important
as available treatments for alopecia are limited in number
as well as in their efficacy4.
The current interest in hair growth promoting agents
MS Orasan, et al
66 Ann Dermatol
Table 1. Experimental groups and treatments
Group Product Manufacturer/city, country Detail Exposure
dose (ml)
Treatment
frequency
I 2% minoxidil, Hairgrow Dar Al Dawa Pharma/Amman, Jordan Topical application 0.3 Daily
II Aminexil, Dercos Vichy Laboratoires/Asnières-sur-Seine, France Topical application 0.3 Daily
III Kerium, Anti-chute La Roche-Posay/Madrid, Spain Topical application 0.3 Daily
IV Control - - - Without
treatment
comes from the perspectives of dermatologists, scientists
as well as pharmacological companies5. Experimental ani-
mal models such as mice, rats, rabbits, sheep and mon-
keys have been used to evaluate the extent of hair
growth6-9. The mouse model, such as the C3H/HeJ mouse,
is one of the most widely used animal model reported for
testing hair growth products, despite the disadvantages
presented by its higher hair density and wave pattern of
hair cycle progression10-12. Cotsarelis13 demonstrated that
in a given person, both the bald areas and the normal
scalp had the same number of stem cells. It has also been
reported that hair follicles of the alopecic scalp lack pro-
genitor cells. This implies a defect in the activation of stem
cells to progenitor cells in the bald scalp. It is known that
hair follicles do not disappear in alopecia, they just de-
crease in size. In order to generate terminal hair, re-
searchers have emphasized the need to identify factors
that, when used topically, may convert stem cells into pro-
genitor cells13.
Results from previous studies have encouraged us to de-
velop our own model for assessing topical therapy for hair
regrowth by using healthy adult white Wistar rats7,14. The
purpose of the current study was to compare the efficacy
of three chemical treatments used in hair loss patients,
namely, 2% minoxidil, Hairgrow (Dar Al Dawa Pharma,
Amman, Jordan), Aminexil, Dercos (Vichy Laboratoires,
Asnières-sur-Seine, France), and Kerium, Anti-chute (La
Roche-Posay, Madrid, Spain). We aimed at determining
the differences in hair regrowth induced by the three hair
promoting agents in a rat model and to assess the results
of treatment by using trichoscopy, hair weight examina-
tion, and morphometry, to identify the product with the
best results from among the three.
MATERIALS AND METHODS
Experimental animals and study design
Thirty-two adult female Wistar-Bratislava albino rats (of
ages 122∼126 days, weighing 200∼250 g) were quar-
antined for 1 week. The animals were held in cages in the
Animal Facility of the Physiology Department (4 rats per
cage) and maintained on a standard laboratory diet and
water ad libitum. They were housed in a room under con-
trolled temperature, with 12 hour light-dark cycles for a
minimum of 7 days prior to the experiment.
The study protocol was submitted to and approved by the
Institutional Animal Ethical Committee (IAEC) of Iuliu
Haţieganu University of Medicine and Pharmacy in Cluj-Na-
poca, Romania (No. 695/07.02.2013). All experiments
were carried in accordance with the Iuliu Haţieganu
University of Medicine and Pharmacy guidelines. All ex-
periments were performed in triplicate.
The rats in all groups were preselected to be in the telogen
(resting) phase of hair growth cycle, based on their age15.
They were randomly assigned to four groups, with each
group consisting of eight rats. Prior to shaving the rats,
general anesthesia was administered with a combination
of ketamine (intraperitoneal 50 mg/kg body weight) and
xylazine (20 mg/kg body weight). On the first day of the
experiment, fur from two rectangular areas (2×4 cm each),
situated on either sides of the spine was removed by using
an animal shaving machine. Shaved area on the left side
of the spine was defined as the control area was left
untreated. The right side was defined as the test area for
application of products to be tested.
The animals were divided into four experimental groups
(Table 1). Rats in groups I to III received 0.3 ml of hair
promoting agent (product) applied topically for 28 days. A
syringe plunger was used to apply the product on the test
area. Animals were isolated for half an hour after topical
application and then housed back to their cages. The rats
in the last group (IV) served as control subjects and re-
ceived no treatment during the experiment. On day 29,
the animals were sacrificed by cervical dislocation and
then evaluated.
Evaluation of hair regrowth efficacy
The assessment of hair regrowth efficacy was performed
for both the test and control area on day 0 and day 28.
The protocol included sedation of the test rats, tricho-
scopic visualization of the test and control area, measure-
ment of the weight of removed hair (1 cm2 area) and skin
Topical Products for Hair Regrowth
Vol. 28, No. 1, 2016 67
biopsy for histological examination. Skin thickness, follicle
count, and percentage (%) of anagen (growing phase of
the hair cycle) induction were studied for morphometry.
Consistency in using the same camera and settings was
maintained in examining animals for trichoscopy. Tricho-
scopy was performed with DermLite100 dermatoscope
(3Gen Inc., San Juan Capistrano, CA, USA) An analytical
balance was used for weighing the hair samples. Biopsy
sampling was performed by the classical surgical method
and not by punch-biopsy technique. Comparisons were
performed between the test and control group, as well as
between the test and control area for each animal. This al-
lowed each rat to be used as its own control.
Trichoscopic visualization of test areas
This was the first step of evaluation and involved the use
of a 4-type scoring system developed by the authors. This
included the development of a rating scale of hair re-
growth for each Wistar rat, interpreted with reference to
the control area of the same animal. Results were reported
as: type 1, uneven hair growth on the test area; type 2,
low hair density (the skin can be easily seen); type 3, mod-
erate hair density (the skin cannot be seen); type 4, high
hair density (full, thick fur).
Hair weight assessment
The second step of hair regrowth evaluation involved
measuring the weight of the hair removed from a surface
area of 1 cm2 by using an analytical balance. The col-
lected hair was placed on an aluminum foil and labeled to
identify the hair as belonging to test or control area.
Weight measurement was performed in the chemistry lab-
oratory of the Department of Physiology. Hair weight was
measured in milligrams (mg) and expressed as mg/cm2.
Measurement of skin thickness and number of hair
follicles
Skin biopsies were sampled from both the test and the
control areas of rats in all groups. The skin biopsies were
immediately fixed in 10% neutral buffered formalin (Chem-
pur; Piekary Śląskie, Poland) and retained for at least 24
hour before processing for standard histopathological
examination. Serial sections of 5 μm were sliced and
stained with hematoxylin and eosin. Follicles were count-
ed manually in all layers of skin by an observer blinded to
the experiment. Skin thickness from epidermis to pan-
niculus carnosus was measured by using conventional
light microscopy (Olympus BX 51 [Olympus, Tokyo, Japan]
microscope equipped with Olympus SP 350 [Olympus]
digital camera and Cell B image analysis software). The
percentage of anagen induction was calculated by using
the following formula: (follicles in subcutaneous lay-
er)×100/(total follicle count).
Statistical analysis
All values were expressed as mean±standard error of
mean. Results of trichoscopy evaluation and hair weight
measurement were analyzed by Student’s t-test. All data
used for the statistical analysis were found to be normally
distributed (Shapiro-Wilk normality test). Statistical analy-
sis of morphometry data was performed by using two-sam-
ple t-test. A value of
p
＜0.05 was considered to be statisti-
cally significant. The Statistical Package for the Social
Sciences 16.0 for Windows (SPSS Inc., Chicago, IL, USA)
and R’ software were used for statistical analysis.
RESULTS
Hair regrowth evaluation by trichoscopy
A general clinical evaluation of all animals was performed
on day 28, at the end of the experimental period (Fig. 1).
Treatment with 2% minoxidil was considered as the gold
standard and the
in vivo
hair regrowth induced by it was
compared with the results achieved with Aminexil and
Kerium therapy in addition to the comparisons involving
control areas and the control group. The hair regrowth no-
ticed in group II (Aminexil) and group III (Kerium) was
lesser than that seen in groups I (minoxidil) or IV
(controls). When evaluated with trichoscopy, the rats from
these two groups had type 1 pattern of hair growth
(uneven hair growth on tested area) and type 2 pattern of
hair growth (low hair density) (Fig. 2, 3). Additionally,
both Aminexil and Kerium treated areas had a lower hair
regrowth effect when compared to control group (group
IV).
Rats in group I (minoxidil) had increased hair growth com-
pared to the control group (Fig. 3). Rats in group I had bet-
ter hair regrowth than the rats in groups II (Aminexil) and
III (Kerium) (Fig. 2, 3). This confirms that 2% minoxidil is
more efficacious than Aminexil and Kerium.
The best hair regrowth in the four groups was observed in
group I (2% minoxidil). Seven out of 8 rats in group I dem-
onstrated type 3 or type 4 pattern of hair growth (moderate
to high hair density). The treatment effects in terms of hair
regrowth in group I were significantly better than the hair
regrowth observed in the control group (Fig. 2, 3).
Hair weight assessment
The weight of newly grown hair in all the test groups was
assessed and compared with that from the control site
(Table 2). Hair weight from test areas was significantly
higher than from the negative control area when com-
MS Orasan, et al
68 Ann Dermatol
Fig. 1. Gross clinical evaluation on day 28.
Fig. 2. Trichoscopy findings on day 0 (A) and day 28 (B).
pared in the same animal in group I (minoxidil) and group
II (Kerium) (
p
＜0.05). The highest hair weight was recorded
in the Kerium treated rats. The hair regrowth stimulation
with 2% minoxidil was significantly better than the hair re-
growth in negative controls (group IV) (
p
＜0.001). Aminexil
topical treatment (group II) had the least regrowth effect as
Topical Products for Hair Regrowth
Vol. 28, No. 1, 2016 69
Table 2. Hair weight assessment mean
Treatment Hair weight (mg/cm2)
p
-value
Minoxidil 44.6±1.1 0.018*
Control site 39.7±1.4
Aminexil 41.4±1.9 0.187
Control site 37.5±2.2
Kerium 48.8±1.7 0.012*
Control site 41.6±1.9
Results are expressed as mean±standard error of mean. *Statisticall
y
significant.
Fig. 3. Trichoscopic examination scoring expressed as mean±
standard error of mean.
Table 3. Histopathologic evaluation for morphometry
Treatment Skin thickness (μm) Follicle count Follicle count in
subcutaneous tissue Anagen induction (%)
p
-value
Minoxidil 1,477.7±63.5 51.4±12.7 33.1±9.1 61.7±10.1 0.045*
Control 1,284.8±67.2 45.3±9.9 19.1±5.6 40.6±5.1
Aminexil 1,378.5±74.8 88.1±13.3 26.4±6.1 27.1±3.7 0.962
Control 1,474.3±64.5 85.0±14.8 28.2±7.1 26.8±4.1
Kerium 1,338.1±67.9 70.9±13.7 27.6±7.2 41.4±6.7 0.033*
Control 1,427.1±167.5 83.4±10.2 24.4±7.4 23.8±5.1
Results are expressed as mean±standard error of mean.
p
-value for anagen induction (%) compared to the negative control area.
*Statistically significant.
compared to all other experimental groups (Table 2).
Histopathological examination of hair regrowth (mor-
phometric assessment)
In this study, increase in thickness of the subcutaneous
layer and the presence of follicles in it were considered as
evidence in support of transition of follicles from telogen
to anagen hair regrowth phase.
Morphological assessment of the hair regrowth process in-
cluded estimation of anagen induction. The transition of
hair growth from telogen phase to anagen phase was
27.1% in rats treated with Aminexil (group III) and 41.4%
in rats treated with Kerium (group II). Anagen induction
was the highest in rats treated with minoxidil at 61.7%
(group I). In all study groups, the results were compared
with the percentage of anagen induction from the un-
treated side of the animal, which served as control (Table 3).
After 4 weeks of topical treatment in group I (minoxidil
2%) an increase in the number of hair follicles (
p
＜0.05 as
compared to control area) was noticed in the subcuta-
neous layer, the majority of which were in the anagen
phase and a few in the catagen phase (Table 3, Fig. 4). In
group II, (Aminexil) the follicle count in the subcutaneous
layer was very low, suggesting that Aminexil induced less
hair regrowth. In group II, the anagen induction in the
treated areas had similar values as the control areas imply-
ing that regrowth was not enhanced by Aminexil treat-
ment (Table 3, Fig. 4). The percentage of anagen induction
was significantly increased following topical application of
Kerium in group III (
p
＜0.05 as compared to control area)
(Table 3, Fig. 4).
On histopathological examination during the anagen
phase of hair growth, follicles were located in the deep
subcutaneous tissue while in the telogen phase, follicles
were present in the dermis itself (Fig. 4).
The results failed to demonstrate significant variation in
skin thickness between the control and treated area in any
of the four experimental groups (Table 3).
DISCUSSION
Hair loss and thinning are commonly encountered dis-
orders in clinical dermatology16. Only two Food and Drug
Administration (FDA) approved hair loss drugs are avail-
able for medical management of hair loss: the dihy-
drotestosterone-suppressing 5 alfa-reductase inhibitor, fi-
nasteride and the antihypertensive potassium channel
opener, minoxidil17,18. Both finasteride and minoxidil are
commonly used in clinical practice. Since finasteride and
minoxidil (2% or 5%) have temporary effects and un-
predictable efficacy, better pharmacological options for
MS Orasan, et al
70 Ann Dermatol
Fig. 4. The effect of the different types of treatments (left column) on hair regrowth in Wistar rats, compared with the negative control
area. The dotted lines indicate the junction between dermis (D) and subcutaneous layer (S) (H&E). The columns on the right illustrate
the percentage of anagen phase induction for each type of treatment (*
p
＜0.05).
treatment are necessary for managing hair loss19.
There are a number of products claiming to treat hair loss
contributing to a multibillion dollar market worldwide.
There is an increase in patents for potential useful or
doubtful anti-hair loss agents20. Several agents advertised
as effective “anti-hair loss” remedies are not supported by
convincing studies. This is the reason why “great expect-
ations” turn into plenty of disappointments21. Much of
those disappointments appear to result from inefficient
drug action and insufficient assessment of the basic path-
ology of hair loss22. There is also lack of studies regarding
the mechanism of action of human hair growth pro-
moters20.
Our study compared several substances that are consid-
ered to be hair growth promoters. Since 2% minoxidil is
regarded as the gold standard treatment for hair loss it was
important to validate minoxidil treatment on a rat model.
We also compared the effect of 2% minoxidil, Hairgrow
(Dar Al Dawa) with that of Aminexil, Dercos (Vichy
Laboratoires), and Kerium, Anti-chute (La Roche-Posay),
with focus on trichoscopy, hair weight, and histomorpho-
metric indices (skin thickness, follicle count, anagen ratio).
Hair growth cyclicity (anagen, catagen, and telogen phas-
es) can be used both as a diagnosis tool of the hair growth
condition, and as a marker of treatment outcome. A
unique feature of the hair follicle, cyclic changes involve
rapid remodeling of both its epithelial and dermal compo-
nents19,23. The main mesenchymal component, the dermal
papilla (DP), plays an important role in inducting new hair
follicles and maintaining hair growth24. To pass from the
resting phase to the anagen phase, the DP cells demon-
strate increased cell division and growth rate. This pas-
sage, therefore, requires a good supply of nutrients and a
toxin-free environment for the growing cells. If these re-
quirements are not fulfilled, the follicles fail to pass from
the resting phase (telogen) to the growing phase (anagen)25.
Topical Products for Hair Regrowth
Vol. 28, No. 1, 2016 71
Taking into consideration the current knowledge about
hair cyclicity, we decided to include in our study Aminexil
and Kerium topical therapy with the assumption that these
compounds promote hair growth. Aminexil, Dercos (Vichy
Laboratoires) is the trade name of Kopexil, an N-oxide.
Kopexil is a chemical compound similar to minoxidil, but
without the piperidine substituent seen in minoxidil. It
contains arginine, aminexil, and SP94 peptide. Arginine
stimulates microcirculation, bringing in essential nutrients
for hair bulb growth. Aminexil (1.5%) helps in reducing
the rate of hair loss by not altering the structure of colla-
gen and maintaining the elasticity of the tissue that sur-
rounds the hair root. The SP94 peptide is captured by the
hair root and helps in nourishing the hair from its root to
the tip by transforming into constructive elements building
up the hair fiber. Vitamin B6 is thought to generate beau-
tiful, shining hair that becomes thicker and stronger from
within26.
Kerium Anti-chute (La Roche Posay) contains Thermal
Spring Water, madecassoside, vitamin B5, and arginine.
The cellular nutrients (vitamin B5+arginine) nourish the
hair roots and give strength to the fiber, while the La
Roche Posay Thermal Spring Water contains anti-free radi-
cal Selenium. This enhances the therapeutic action of ma-
decassoside, which in turn inhibits local micro-irritation
and its spread to the capillary bulb. Aminexil reduces the
accelerated aging of the roots by countering fibrosis and
stiffening of collagen sheets and by fastening the hair root
within the scalp21,22. The treatment needs one application
every day for a minimum of 3 applications every week, by
using one of the two adapted applicators (for men and
women).
The rats used in our experiment were 122∼126 days old
and therefore, in the telogen phase of hair growth cycle.
The experiment lasted four weeks and during this time,
the rats passed through an almost complete hair cycle7.
According to our results, minoxidil 2% and Kerium treat-
ment contributed to the increase in the number of hair fol-
licles observed in the subcutaneous layer (
p
＜0.05 as
compared to the control area), with the majority being in
the anagen phase. Similar results were not observed with
Aminexil, suggesting that it did not have the same benefi-
cial effects on hair regrowth. Trichoscopy demonstrated
that the best hair regrowth was achieved with 2% minox-
idil, with treated rats developing type 3 and type 4 pat-
terns of hair regrowth (moderate to high hair density) on
test areas.
Previous microscopy studies on mice demonstrated an as-
sociation between anagen induction and increased skin
thickness, follicle count and macroscopic development of
skin pigmentation27. In our study, the statistically sig-
nificant anagen induction (
p
＜0.05) was not accompanied
by increase in skin thickness.
Our results confirmed hair regrowth with Kerium as seen
on weight assessment and histopathological examination.
A similar confirmation of good hair regrowth was not
demonstrated in the Aminexil treated group. On tricho-
scopy, Aminexil and Kerium treated groups had lesser hair
growth effects than minoxidil.
An important outcome of our study was the validation of
the hair regrowth effect of 2% minoxidil on Wistar rats.
Minoxidil, which was first used as an orally administered
antihypertensive drug, was associated with interesting side
effects of increased hair growth on the scalp and darken-
ing of fine body hairs. In 1988 the FDA approved 2% min-
oxidil for treating androgenic alopecia in men (for cen-
tral/vertex hair loss only), and in 1991 its use was permit-
ted for women as well18. Since then, minoxidil has been
marketed under many trade names. Minoxidil slows or
stops hair loss and promotes hair growth by a mechanism
that is still uncertain. Since the telogen phase follicles are
shed and are replaced by new anagen hairs, it is possible
that minoxidil acts as a nitric oxide agonist. Minoxidil is a
potassium channel opener, causing hyperpolarization of
cell membranes, thus allowing more oxygen, blood and
nutrients to reach the follicle28. Minoxidil is also a vaso-
dilator and increases the cutaneous blood flow to the
scalp29. Minoxidil does not decrease dyhydrotestosterone
(DHT) or 5-alpha reductase, the enzyme responsible for
accumulation of DHT around the hair follicle, ruling out
the therapeutic action of minoxidil on the hormonal or ge-
netic causes of hair loss. Minoxidil is administered topi-
cally and is available in two concentrations: 2% and 5%30.
The usual dosage is 1 mg per day, applied twice daily to
the affected area and followed by slight massage of the
scalp. It is advised that the treatment area should not get
in contact with water for at least four hours after applica-
tion in order to achieve maximum results17. Studies sug-
gest ceasing of hair regrowth and onset of hair loss in 30
to 60 days if minoxidil treatment is stopped for more than
6 months30. This happens because without the beneficial
environment created by minoxidil, the follicles return to
their primary condition, and are exposed to DHT resulting
in their shrinkage and destruction. Minoxidil must be used
indefinitely for continuous support of existing hair follicles
and maintenance of the experienced hair regrowth, if any.
Uno and Kurata31 studied hair growth promoters, minox-
idil, diazoxide, and Cooper peptides, on fuzzy rats. Their
results with minoxidil demonstrated a conversion of short
vellus hairs to prolonged terminal hairs. They also noticed
an enlargement of the follicular size with prolongation of
anagen phase due to an enhanced rate of cell proliferation.
MS Orasan, et al
72 Ann Dermatol
In our experiment, though Kerium showed a significant in-
crease of anagen induction when compared with control
group, this finding was not consistently supported on tri-
choscopic examination. The explanation could be that tri-
choscopy is at best an approximation of hair growth and
does not provide an exact measurement of newly grown
hairs. It cannot quantify minor increases in hair density,
(as one cannot count the number of hairs per unit or de-
termine their diameter) which still are considered reliable
signs of hair regrowth. Conversely, morphometric evalua-
tion as well as hair weight evaluations are quantitative,
objective methods and can determine slight increases in
hair density.
Our results suggest that 2% minoxidil topical application
is more efficacious than Aminexil or Kerium in inducing
hair regrowth as assessed by trichoscopy, hair weight ex-
amination, and morphometric assessment. Microscopic
data obtained from the validation study confirms that the
topical administration of 2% minoxidil affects the normal
hair cycle by inducing anagen phase of hair growth in the
resting follicles. We used an animal model of hair re-
growth to demonstrate that not all the products recom-
mended for human use have the same hair regrowth
efficacy. This study validates the hair regrowth effect of
minoxidil and also demonstrates that Kerium treatment in-
duces good hair regrowth in Wistar rats.
ACKNOWLEDGMENT
This paper was published under the frame of the European
Social Found, Human Resources Development Operational
Programme 2007-2013, project no. POSDRU/159/1.5/S/
138776.
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