Application Of Minoxidil Research Articles

890 Impact of a stimulating cream shampoo treatment on the penetration of minoxidil through hair follicles

Androgenetic alopecia (AGA) presents clinically with reduced hair density and hair width due to shortening of the hair cycle in genetically predisposed scalp areas. The effectiveness of Minoxidil in AGA has been demonstrated in numerous randomized controlled trials. However, there is a need to enhance its bioavailability in hair follicles. Our laboratory developed a stimulating cream shampoo that prepares the scalp to reactivate its vital functions and those of the hair. This shampoo can be used before application of Minoxidil in order to help the penetration of Minoxidil. The aim of this study was to investigate this hypothesis evaluating the difference of Minoxidil penetration through hair follicles following topical application with and without pre-treatment with the stimulating cream shampoo. The skin penetration study was realized at finite conditions (10μl/cm2) on human scalp. The scalp was mounted on dynamic cells using radiolabelled compounds (3H-Minoxidil). 3H-Minoxidil was quantified in the different compartments of the skin (surface, SC, hair follicles, skin and receptor fluid) by scintillation counting. The mass balance was in accordance with guidelines (100 ± 15%) and permits to validate the study. After 10 min, significant higher quantities of Minoxidil were recovered into the hair follicles and scalp after pre-treatment with the stimulating cream shampoo. Indeed, the quantity of Minoxidil recovered into the hair follicles was 1.41 μg and 0.29μg, with and without shampoo pretreatment. In the scalp, Minoxidil quantity reached 32.02 μg and 6.62μg, with and without shampoo, respectively. The data obtained permits to conclude on the enhancing effect of the stimulating cream shampoo on Minoxidil penetration and help to target the hair follicles.

Hair Loss due to Electromagnetic Radiation from Overuse of Cell Phone

Mobile phone usage is nearing 90% of the world population. Harmful effects of Electromagnetic (EMG) radiation have been a concern for regulation. Safe Specific Absorption Rate (SAR) as watt/kg is defined for thermal effects, but EMG has non thermal effects as well. EMG can affect genes, neural tissue, endocrine regulation and sperms. Research workers have pointed out the mechanism of EMG radiation to be acting through DNA breakage and formation of Reactive Oxygen Species (ROS). We are reporting a case of hair loss over the temporal region from repeated, prolonged conversations on mobile phone. Biopsy is negative for any other pathology of hair loss. Use of antioxidants, vitamins, minerals, can aid in recovery of the damaged cells. Low dose 2% minoxidil application combined with nutritional therapy, limiting the duration of mobile phone usage and having hands free chord to keep the mobile phone instrument away from the ear, was seen to help in regrowth of the hair.

Frontal Edema Due to Topical Application of %5 Minoxidil Solution Following Mesotherapy Injections.

Sir, A 37‑year‑old woman referred to our clinic complaining of hair loss. On dermatological examination, thinning of the hair on vertex was noticed. Laboratory findings were in normal limits. She was diagnosed as female androgenetic alopecia and decided to perform scalp mesotherapy. Three sessions of multiple intradermal biotin injections were performed by point by point mesotherapy injection technique [1] at 15 days intervals. There were not detected any complications after these biotin mesotherapy sessions. Fourth biotin mesotherapy treatment was performed similar to previous sessions, additionally, immediately after mesotherapy injections, approximately in 10 min, topical %5 minoxidil solution was topically applied with gentle massage. 16 h after the fourth session a firm frontal edema was developed, erythema and pain were not associated to edema [Figure 1]. Frontal edema resolved gradually in 2 days. After 2 weeks, the fifth biotin mesotherapy treatment was performed again without topical application of minoxidil and no complication was detected after the fifth session. Minoxidil solution can be used in the treatment of alopecia by topical application or by mesotherapy injection. It is shown that minoxidil enhances hair growth by prolonging the anagen phase and induces new hair growth. [2] It is instructed not to use minoxidil over than 1–2 cc within mesotherapy cocktail because the hypotension can be seen due to excess vasodilatation. [2,3] The vasodilator effect of minoxidil is well‑known, and vasodilatory edema is a well‑known side effect of vasodilators. [4] With respect of these knowledges, we comment the reason of frontal edema in this patient is due to the excessive absorption of topical applicated %5 minoxidil after hundreds of mesotherapy injections. Though minoxidil was applicated topically, it was absorpted too much by the pores of injected sites and effected as a locally vasodilator and caused the frontal edema. The previous mesotherapy sessions and the last mesotherapy sessions were not complicated, so we suggest the biotin mesotherapy injection does not have a role in this side effect. In the medical literature, we could not found a reported case describing facial edema due to minoxidil application neither by topically nor by mesotherapy injection. However, in patient forum sites we detected that patients noticed “puffy face” due to topical application of minoxidil solution. We present this case to remind the locally edematous effect of minoxidil solution.

Guidelines for the management of androgenetic alopecia (2010)

Guidelines for the management of androgenetic alopecia (2010) Ryoji TSUBOI, Satoshi ITAMI, Shigeki INUI, Rie UEKI, Kensei KATSUOKA, Sotaro KURATA, Takeshi KONO, Norimitsu SAITO, Motomu MANABE, Masashi YAMAZAKI, GUIDELINES PLANNING COMMITTEE FOR THE MANAGEMENT OF ANDROGENETIC ALOPECIA Department of Dermatology, Tokyo Medical University, Tokyo, Department of Regenerative Dermatology, Osaka University Graduate School of Medicine, Osaka, Department of Dermatology, Juntendo Tokyo Koto Geriatric Medical Center, Tokyo, Department of Dermatology, School of Medicine, Kitasato University, Sagamihara, Kurata Clinic, Beppu, Department of Dermatology, Nippon Medical School, Tokyo, and Department of Dermatology, Akita University Graduate School of Medicine, Akita, Japan

The Cost Effectiveness of Topical Minoxidil Therapy in Management of Baldness

“Use it or loss it (Rogaine),” is an advertisement as a cure for baldness. Rogaine is a commercial name for Minoxidil. Minoxidil is a vasodilator used orally for treatment of severe to malignant hypertension. Minoxidil therapy also causes hypertrichosis (increase of body hair). This drug is used topically to treat baldness.Minoxidil is not effective in halting the receding hairline on the frontal scalp. Its antibald effect is limited to the vertex of the head. It takes several months (2–4) to regrow hair by twice‐a‐day application. Continuous use of Minoxidil topical solution is needed to maintain hair regrowth. Stopping Minoxidil application causes loss of newly regrown hair in 3 to 4 months.Purpose of this case study will answer several questions. Is Minoxidil effective against baldness? Is it a permanent, cost‐effective remedy for baldness? What age group will get the maximum benefit from Minoxidil therapy? What types of baldness are amenable to Minoxidil therapy? Is it effective in female baldness? Is Rogaine free from remarkable adverse effects? What are the causes of baldness? Is there any permanent remedy for baldness?

Minoxidil activates β-catenin pathway in human dermal papilla cells: A possible explanation for its anagen prolongation effect

It is believed that the length of the actively growing phase of the anagen hair cycle mainly contributes to hair length. Recent studies showed that maintenance of β-catenin activity in the dermal papilla cells (DPCs) enables hair follicles to keep actively growing. Topical minoxidil treatment promotes hair growth in men with androgenetic alopecia, suggesting that minoxidil may prolong the actively growing phase of the anagen hair cycle. To investigate whether minoxidil prolongs the anagen hair cycle in mice and, if so, to investigate whether minoxidil activates β-catenin pathway in human DPCs. Dorsal skins of C57BL/6 mice were depilated to synchronize the hair cycle. After 10 days, 3% minoxidil were topically applied daily for 10 days. Sections of back skins were stained with hematoxylin and eosin. Hair follicles were graded and hair cycle score (HCS) was calculated. Cultured human DPCs were transiently transfected with the β-catenin responsive TCF reporter plasmid (pTopflash) and corresponding negative control reporter (pFopflash) to assess the activity of β-catenin signaling by minoxidil. Immunofluorescence staining and immunoblot were performed to examine the expression and localization of β-catenin in the presence or absence of minoxidil. Phosphorylation of GSK3β, PKA and PKB were also examined by immunoblot after minoxidil treatment. RT-PCR analysis and immunoblot were employed to investigate the expression of β-catenin pathway targets in DPCs, such as Axin2, Lef-1, and EP2. Modest extension of anagen phase thereby delay of catagen progression was observed by application of minoxidil in mice. Minoxidil stimulated the transcriptional activity of pTopflash but not pFopflash. Nuclear accumulation of β-catenin was also observed after minoxidil treatment. Immunoblot further showed that minoxidil treatment increases the phosphorylation of GSK3β, PKA and PKB. Moreover, minoxidil induced Axin2, Lef-1, and EP2 expression. Our results strongly suggest that minoxidil extends the anagen phase by activating β-catenin activity in the DPCs.

The effect of Gyungokgo-gamibang extract on hair growth and protein expression in mice

Objective : Present study was carried out to investigate the effect of Gyungohkgo-gamibang extract on hair growth and protein expression in an alopecia model of C57BL/6 mice. Methods : Mice were divided into 3 experimental groups including normal (vehicle), Gyungohkgo-gamibang extract (YNS-10) and 5% minoxidil-treated group. The test materials were daily applied with 0.1 ml per mouse on shaved dorsal skin for 3 weeks. The hair growth was monitored by photograph at 5, 10, 15, 21 days after topical application. Then the changes of hair density and hair thickness in the hair-removed area were evaluated by phototrichogram using folliscope. Also the expression level of growth factors related to hair growth was measured by western blotting. Results : Application of minoxidil or YNS-10 stimulated the hair growth compared to vehicle treatment. Therefore hair density of minoxidil or YNS-10 application was increased about 200% and 210% more than in vehicle application on 14 day, respectively. And hair thickness of both minoxidil group and YNS-10 group was increased about 220% and 210 % more than in vehicle spreading on 14 day, respectively. Futhermore the protein expression of IGF-1 and VEGF were significantly up-regulated on 7 day in YNS-10 and minoxidil-spreaded group compared to vehicle-applied group. Conclusion : These data suggest that YNS-10 has potent stimulating activity on hair growth in C57BL/6 mice and potential usefulness as ingredients of hair tonic and hairrestore.

The Cost Effectiveness Of Topical Minoxidil Therapy In Management Of Baldness

“Use it or loss it (Rogaine),” is an advertisement as a cure for baldness. Rogaine is a commercial name for Minoxidil. Minoxidil is a vasodilator used orally for treatment of severe to malignant hypertension. Minoxidil therapy also causes hypertrichosis (increase of body hair). This drug is used topically to treat baldness. Minoxidil is not effective in halting the receding hairline on the frontal scalp. Its antibald effect is limited to the vertex of the head. It takes several months (2-4) to regrow hair by twice-aday application. Continuous use of Minoxidil topical solution is needed to maintain hair regrowth. Stopping Minoxidil application causes loss of newly regrown hair in 3 to 4 months. Purpose of this case study will answer several questions. Is Minoxidil effective against baldness? Is it a permanent, cost-effective remedy for baldness? What age group will get the maximum benefit from Minoxidil therapy? What types of baldness are amenable to Minoxidil therapy? Is it effective in female baldness? Is Rogaine free from remarkable adverse effects? What are the causes of baldness? Is there any permanent remedy for baldness?

Exogenous stimulations change nude mouse hair cycle pattern

The pattern of murine hair growth has been seen as an unpredictable and irregular process. In this study, nude mice were used to investigate the hair growth pattern and find the impact of exogenous stimulations on changing the hair growth pattern. We found nude mouse hair appeared in waves from the head to the posterior part of the back for the first time. Amongst all of the six groups, male nude mice had a more regular hair cycle pattern than females: from the head to the posterior part of the back. When there was no hair on the back of a nude mouse, we named this time the ‘no-hair phase’ and the opposite was the ‘hair-existing phase’. Exogenous stimulations significantly elongated the hair-existing time and shortened the no-hair time but did not work on the hair growth pattern. For male mice, topical application of minoxidil created a shorter no-hair phase and a longer hair-existing phase than other treatment methods. For female nude mice, minoxidil had little more effect than a wound in shortening the no-hair phase. A wound was better than minoxidil in elongating the hair-existing phase in female nude mice, and this effect was indistinctive.

Efficacy of 5% Minoxidil versus Combined 5% Minoxidil and 0.01% Tretinoin for Male Pattern Hair Loss

5% topical minoxidil solution has been widely used to stimulate new hair growth and help stop hair loss in men with androgenetic alopecia (AGA). However, it is not convenient for patients to continue applying the solution twice daily on a regular basis. Tretinoin is known to increase the percutaneous absorption of minoxidil and, therefore, to enhance the response of AGA to minoxidil. For this reason, it was assumed that tretinoin would be helpful in alleviating the inconvenience associated with the recommended twice-daily application of minoxidil. To compare the efficacy and safety of therapy using a combined solution of 5% minoxidil and 0.01% tretinoin once daily with those of the conventional 5% topical minoxidil therapy applied twice daily in the treatment of AGA. A total of 31 male patients (aged 28-45 years, mean 39.7+/-4.5) with AGA (Hamilton-Norwood classification type III-V) were randomly assigned into two groups, one in which 5% minoxidil was applied to the scalp twice daily and the other in which the combined agent was applied once daily at night together with a vehicle placebo in the morning. The efficacy parameters were: (i) changes in total hair count, non-vellus hair count, anagen hair ratio, linear hair growth rate, and mean hair diameter assessed by macrophotographic image analysis; and (ii) the patient's and investigator's subjective assessments. After therapy, increases in the macrophotographic variables of total hair count and non-vellus hair count were shown in both treatment groups. There were no statistically significant differences between the two treatment groups with respect to changes in macrophotographic variables or scores on subjective global assessments by patients and the investigator. The incidence of adverse effects such as pruritus or local irritation was similar in the 5% minoxidil group (4 of 14 subjects) and the combined agent group (5 of 15 subjects). The efficacy and safety of combined 5% minoxidil and 0.01% tretinoin once-daily therapy appear to be equivalent to those of conventional 5% minoxidil twice-daily therapy for the treatment of AGA.

Hormone‐related hair disorders – from clinical needs to new therapeutic perspectives

The hair follicle and its appendages are important target structures for hormones. Plasma levels, local hormone metabolism and differential receptor expression regulate hair growth and hair cycling as well as sebaceous gland function. Even minor imbalances in this system, e.g. abnormal expression of hair follicle‐associated isoenzymes, may cause clinical symptoms such as hair loss, seborrhoea or hirsutism.Conventional therapeutic strategies, which aim to control peripheral hyperandrogenism, include systemic administration of androgen inhibitors (e.g. oral contraceptives, GnRH analogues), peripheral androgen blockers (CPA, CMA, glutamide, finasteride) as well as topical application of estrogens. As our knowledge about hormone systems and their complex interactions increases, new molecules are gaining importance: rosiglitazone and metformin are compounds which increase the sensitivity to insulin, topical application of minoxidil has been shown to regulate perifollicular blood flow and vascularization, and anti‐inflammatory compounds can as well be beneficial in the treatment of androgenetic alopecia.Because such therapies are, still, rather unspecific, current research focuses on the development of individualized strategies which allow to specifically treat the various manifestations caused by hormone‐related disorders. From our perspective, the aims of future drug development are as follows.In the first place, the identification of new targets, possibly beyond sex steroids in the narrow sense is highly important. Components of the POMC‐system, for example, have been shown to regulate cell differentiation and also hair cycling.And secondly, to develop drug delivery systems, which allow to specifically directing active compounds to target structures. Such improved drug delivery may allow to reduce side‐effects and to increase the efficacy of current therapies. Studies by our group and others suggest that microparticles, due to their ability to aggregate in the hair follicle openings, are promising drug delivery systems. In fact, we recently reported that the penetration depths of transcutaneously applied microparticles into the follicular duct depends on the size of the particles and on the dimension of the hair follicle, suggesting that particle‐based drug delivery systems allow to selectively target hair follicle compartments such as the entry level of the sebaceous duct or the bulge region.

K+ Channel Activation with Minoxidil Stimulates Nasal-Epithelial Ion Transport and Blunts Exaggerated Hypoxic Pulmonary Hypertension

Increased pulmonary capillary pressure and inhibition of alveolar Na+ transport putatively contribute to the formation of pulmonary edema in alveolar hypoxia such as at high altitude. Since both events might be linked to the inhibition of K+ channels, we studied whether in vivo application of minoxidil, a stimulator of ATP-gated K channels (K+ ATP channel activator) prevents both effects. In a double- blind, placebo-controlled crossover study on 17 volunteers with no known susceptibility to high altitude pulmonary edema, we tested whether a single dose of minoxidil (5 mg) prevents pulmonary hypertension and inhibition of nasal-epithelial Na+ transport in normobaric hypoxia (12% O2, 2 h). In hypoxia, arterial SO2 was decreased to about 80%, and systolic pulmonary artery pressure (PAP) measured by Doppler echocardiography increased significantly from approximately 25 mmHg (normoxia) to approximately 38 mmHg (hypoxia; range 22 to 61 mmHg). Minoxidil decreased PAP in hypoxia in those individuals who had the highest increase in PAP in hypoxia when taking placebo. Nasal potentials decreased by about 10% in hypoxia. Although minoxidil had no effect on nasal potentials in normoxia, it increased nasal potentials significantly above normoxic control values after 2-h hypoxia. These results show that the K+ ATP activator minoxidil prevents the decrease in nasal-epithelial potential by hypoxia and seems to blunt an exaggerated increase in PAP in acute hypoxia.

Determination of the sildenafil effect on alopecia areata in childhood: An open‐pilot comparison study

Background: Alopecia areata is an immunologically mediated cessation of hair growth primarily involving, but not limited to, the scalp. The treatment of alopecia areata involves promotion of hair growth (for instance with topical minoxidil application), immunosuppression (intralesional or systemic steroid therapy, phototherapy) or immunomodulation (anthralin, dinitrochlorobenzene, diphenylcyclopropenone, squaric acid dibutylester). All these medications have some disadvantages and difficulties for the treatment of children with alopecia areata. Objective: To use an open‐pilot study to assess the efficacy of topical 1% sildenafil in children diagnosed with alopecia areata. Methods: Eight patients with (⩽25% of scalp surface area involvement) alopecia areata who were refractory to previous topical treatments applied 1% sildenafil twice daily for 3 months. All the patients completed the study. Results: Two patients experienced vellus‐type hair growth and one patient had terminal hair growth. However, these outcomes were accepted as the spontaneous regression of the disease. Conclusion: We cannot recommend the use of topical 1% sildenafil for the treatment of alopecia areata without further evidence of its therapeutic benefit.

Topical minoxidil counteracts stress-induced hair growth inhibition in mice.

Stress has long been suspected as a possible cause of hair loss in various species, even though convincing experimental evidence has not been available. Recently, we have shown in a murine model that sonic stress alters hair growth and cycling in vivo, and have postulated the existence of a 'brain-hair follicle axis' (BHA). In order to study whether a clinically available and widely used topically active hair growth stimulator mitigates stress-triggered hair growth inhibition in this stress model, we have applied a 5% minoxidil solution. Female CBA/J mice were depilated and randomized in to two groups: control (n = 20) and sonic stress (n = 20). These groups were further divided and either treated daily with 5% minoxidil solution or vehicle alone. The stress group was exposed to sonic stress for 24 h starting 14 days after anagen induction by depilation. All mice were sacrificed 16 days after the depilation and assessed by quantitative histomorphometry. Sonic stress significantly increased the number of hair follicles with apoptotic cells and inhibited intrafollicular keratinocyte proliferation. In addition, the number of clusters of perifollicular MHC class II+ cells and degranulated perifollicular mast cells was significantly enhanced in the stressed mice. In accordance with previous findings, all stressed mice showed an advanced hair cycle progression towards catagen. All of these stress-induced hair growth inhibitory changes along the BHA were down-regulated by topical minoxidil application. This encourages one to explore clinically whether topical minoxidil is a safe and effective pharmacologic tool for the management of stress-associated telogen effluvium in humans.

Tricorrexis nudosa localizada por aplicación compulsiva de minoxidil

Abstract—The case of a 23-year-old woman with bitemporal recession of hair, treated with topic 3% minoxidil is reported. The patient developed a localized trichorrhexis nodosa of the scalp hair after compulsive external application of minoxidil during two months.

Topical Minoxidil in the Treatment of Male Erectile Dysfunction

Topically applied 2% minoxidil solution has been reported to increase diameter, rigidity and arterial flow to the penis. As a result it has been suggested as a possible treatment for erectile dysfunction. A total of 21 patients received 2% minoxidil for treatment of erectile dysfunction with instructions to apply 1 cc of the solution slowly over the glans penis 20 minutes before intercourse. Average patient age was 52.5 years (range 29 to 65 years). The etiology of the impotence was neurogenic in 8 patients, vascular in 7, psychogenic in 4 and other causes in 2. Two patients also had clinical evidence of venous incompetence and 4 were diabetics. One patient with psychogenic impotence noticed improvement in the duration of erection but no increase in rigidity or size after minoxidil application. One patient with impotence after excision of a Peyronie’s plaque reported a rigid erection adequate for intercourse after using minoxidil. This patient subsequently was able to achieve erections without using minoxidil. The remaining 19 patients had no improvement in erectile rigidity or the ability to obtain or maintain an erection. One patient did notice some mild burning on the glans penis after applying the minoxidil. No other side effects were noted in any patient. These results indicate that 2% topical minoxidil solution is not effective when applied to the penis in the treatment of erectile dysfunction. It is possible that a higher concentration, a different delivery medium or a different chemical composition may yield better results.

Histologic response to topically applied minoxidil in male-pattern alopecia

The histopathology of androgenetic alopecia is characterized by reductions in follicular size and mean hair shaft diameter without significant reduction in follicular density.1 The proportion of hairs found in anagen is diminished with a corresponding increase in hairs in normal telogen, plus a marked increase in a persistent stage of telogen. The telogen germinal unit is the term given by Headington2 to the structure that represents a persistence of telogen after shedding of the club hair but in which anagen has not been re-established.Regrowth of scalp hair following topical application of minoxidil has been demonstrated in both primates3,4 and humans5,6 suffering from androgenetically determined alopecia. As part of a nationwide multicenter trial of topical minoxidil in male-pattern alopecia, scalp biopsy specimens were obtained before and after treatment to determine what histopathologic changes might be found and if this might help us understand the way in which the clinically observed regrowth of hair might occur.

Nongenotoxicity of minoxidil in murine hair follicles as determined by the nuclear aberration assay

A 1-cm 2 area on the back of CD1 mice was prepared for topical application of minoxidil, N-methyl- N-nitrosourea (MNU), or cyclophosphamide (CY) by clipping or plucking hair from a patch of skin. Plucking stimulates hair follicle cell division while clipping does not. Minoxidil was topically administered for 8 consecutive days. CY or MNU was administered topically once on the eighth day postplucking. The incidence of nuclear aberrations and mitotic figures were measured in hair follicles while frequency of micronuclei and the ratio of RBC PCE were measured in the bone marrow. Results with minoxidil showed no increase in either nuclear aberrations in the hair follicle or micronuclei in the bone marrow. These results suggest that topically applied minoxidil is not genotoxic. In contrast, a dose-dependent effect of MNU on the incidence of nuclear aberrations in the hair follicle was seen. CY induced a dose-dependent increase in the incidence of micronuclei in the bone marrow and in nuclear aberrations in the hair follicle after topical application. Minoxidil applied to clipped mice significantly increased the incidence of mitotic figures above that seen in both the clipped and plucked controls. This suggests that minoxidil is a mitogenic agent in the hair follicle. These findings are consistent with the success of topically applied minoxidil in the treatment of alopecia areata.

Topical minoxidil in the treatment of male pattern alopecia.

Male pattern hair loss (androgenetic alopecia) is a common problem. In fact, it affects nearly all males to some degree. Expression of the disorder is variable, and while it is never life-threatening, it often becomes a major source of consternation. The biology of the process is poorly understood, and no current therapy can halt or reverse the process. Only cosmetic surgery, which is painful, time consuming, and expensive, has been effective. In the past 7 years, since it was noted that a patient taking minoxidil for hypertension had reversal of male pattern hair loss, awareness of a possible therapeutic role for topical minoxidil in the management of this disorder has grown among physicians, scientists, and the general public. It can be concluded from available data that topical application of minoxidil is effective in providing cosmetically satisfying thickening of hair in a select group of individuals with male pattern hair loss. The drug's mechanism of action remains obscure. No serious side effects have been demonstrated with its use, however, and it is therefore advised in selected patients.

The stumptailed macaque as a model for baldness: effects of minoxidil

Synopsis Topical application of minoxidil in bald scalps of stumptailed macaques successfully induced regrowth of terminal hairs. The rate and degree of hair growth by minoxidil are much greater in the early stage of baldness in adolescent and young adults. Minoxidil also prevented the development of baldness when applied on non-bald scalps of peri-adolescent animals. Morphometric analysis of hair follicles (folliculograms) has brought a new aspect in observing cyclic dynamics and growth (transformation) of hair follicles. Using this analytic method and autoradiographic observation of DNA synthesis of hair follicles, the action of minoxidil appears to be a potent mitotic stimulator of the follicular as well as peri-follicular germinal (or reserve) cells, thus inducing an enlargement of vellus follicles through the process of cyclic growth and maintaining anagen follicles in the growing phases. Most importantly, minoxidil has no influence in epidermal keratinocytes, sebaceous glands and other dermal components. During almost 3 years of consecutive treatment, the animals showed no detectable local or systemic side effects when examined by laboratory tests of blood cells, chemistry, steroid hormones, measurement of blood pressure and EKG test.