Psychological Effect, Pathophysiology, and Management of Androgenetic Alopecia in Men
2005; Elsevier BV; Volume: 80; Issue: 10 Linguagem: Inglês
10.4065/80.10.1316
ISSN1942-5546
AutoresDow B. Stough, Kurt S. Stenn, Robert S. Haber, William M. Parsley, James E. Vogel, David A. Whiting, Ken Washenik,
Tópico(s)melanin and skin pigmentation
ResumoAndrogenetic alopecia in men, or male pattern baldness, is recognized increasingly as a physically and psychologically harmful medical condition that can be managed effectively by generalist clinicians. This article discusses the clinical manifestations, epidemiology, physical and psychosocial importance, pathophysiology, diagnosis, and management of androgenetic alopecia in men. Androgenetic alopecia affects at least half of white men by the age of 50 years. Although androgenetic alopecia does not appear to cause direct physical harm, hair loss can result in physical harm because hair protects against sunburn, cold, mechanical injury, and ultraviolet light. Hair loss also can psychologically affect the balding individual and can influence others’ perceptions of him. A progressive condition, male pattern baldness is known to depend on the presence of the androgen dihydrotestosterone and on a genetic predisposition for this condition, but its pathophysiology has not been elucidated fully. Pharmacotherapy, hair transplantation, and cosmetic aids have been used to manage male pattern baldness. Two US Food and Drug Administration-approved hair-loss pharmacotherapies—the potassium channel opener minoxidil and the dihydrotestosterone synthesis inhibitor finasteride—are safe and effective for controlling male pattern baldness with long-term daily use. Regardless of which treatment modality is chosen for male pattern baldness, defining and addressing the patient's expectations regarding therapy are paramount in determining outcome. Androgenetic alopecia in men, or male pattern baldness, is recognized increasingly as a physically and psychologically harmful medical condition that can be managed effectively by generalist clinicians. This article discusses the clinical manifestations, epidemiology, physical and psychosocial importance, pathophysiology, diagnosis, and management of androgenetic alopecia in men. Androgenetic alopecia affects at least half of white men by the age of 50 years. Although androgenetic alopecia does not appear to cause direct physical harm, hair loss can result in physical harm because hair protects against sunburn, cold, mechanical injury, and ultraviolet light. Hair loss also can psychologically affect the balding individual and can influence others’ perceptions of him. A progressive condition, male pattern baldness is known to depend on the presence of the androgen dihydrotestosterone and on a genetic predisposition for this condition, but its pathophysiology has not been elucidated fully. Pharmacotherapy, hair transplantation, and cosmetic aids have been used to manage male pattern baldness. Two US Food and Drug Administration-approved hair-loss pharmacotherapies—the potassium channel opener minoxidil and the dihydrotestosterone synthesis inhibitor finasteride—are safe and effective for controlling male pattern baldness with long-term daily use. Regardless of which treatment modality is chosen for male pattern baldness, defining and addressing the patient's expectations regarding therapy are paramount in determining outcome. Management of androgenetic alopecia in men, a common dermatologic condition also known as male pattern baldness, has historically been outside the scope of the generalist clinician's practice—perhaps primarily because of its perceived inconsequentiality and the lack of nonsurgical strategies for effective management. However, because of ongoing research and recent developments, androgenetic alopecia in men is recognized increasingly as a physically and psychologically harmful medical condition in some men1Cash TF The psychosocial consequences of androgenetic alopecia: a review of the research literature.Br J Dermatol. 1999; 141: 398-405Crossref PubMed Scopus (182) Google Scholar2Cash TF The psychology of hair loss and its implications for patient care.Clin Dermatol. 2001; 19: 161-166Abstract Full Text Full Text PDF PubMed Scopus (120) Google Scholar that can be managed effectively by generalist clinicians. Therefore, rather than being inconsequential among these men, androgenetic alopecia can be a harmful condition that warrants intervention. Advances in surgical techniques make hair loss more amenable to treatment than ever before; also, pharmacotherapy is now available that can retard, stop, or partially reverse hair loss, can stimulate some hair regrowth,3Messenger AG Medical management of male pattern hair loss.Int J Dermatol. 2000; 39: 585-586Crossref PubMed Scopus (10) Google Scholar and is safely prescribed on an outpatient basis. With the introduction of effective and tolerable pharmacotherapy, generalist clinicians who are not experts in surgical techniques involving hair transplantation can offer effective intervention. The general public's increasing knowledge of and readiness to explore pharmacological and surgical solutions to cosmetic problems including baldness has contributed to an upsurge in patient requests to generalist clinicians for intervention options against hair loss. This article, intended to provide clinicians with the most current information about androgenetic alopecia in men, discusses the clinical manifestations, epidemiology, psychosocial and physical importance, pathophysiology, diagnosis, and management of this condition. Hair loss from androgenetic alopecia in men is progressive and occurs typically in a characteristic pattern, beginning with recession of the frontal hairline and hair loss in the vertex or crown and progressing to complete loss of hair over the frontal and vertex scalp regions.4Ellis JA Sinclair R Harrap SB Androgenetic alopecia: pathogenesis and potential for therapy.Expert Rev Mol Med. 2002; 4: 1-11Crossref Google Scholar5Feinstein R Androgenetic alopecia.Available at: www.emedicine.com/derm/topic21.htmGoogle Scholar In the most severe form of androgenetic alopecia in men, hair may be present only in a ring around the head in the temporal, parietal, and occipital regions of the scalp. This progression is characterized most often by the 7 categories of the Hamilton-Norwood scale,6Norwood OT Hair Transplant Surgery. Charles C Thomas, Springfield, Ill1973: 3-16Google Scholar which assists in the diagnosis and monitoring of hair loss. Hair loss does not conform to this progression in all individuals. The age at onset of androgenetic alopecia in men varies, but occurs on average in men in their mid-20s. The prevalence and severity of androgenetic alopecia in men increase directly with age. Because male pattern baldness depends on circulating androgens (see “Pathophysiology” section), the condition is not observed in prepubescent children. Androgenetic alopecia is most pervasive among middle-aged to elderly white men.7Hamilton JB Patterned loss of hair in man: types and incidence.Ann N Y Acad Sci. 1951; 53: 708-728Crossref PubMed Scopus (658) Google Scholar, 8Birch MP Messenger AG Genetic factors predispose to balding and non-balding in men.Eur J Dermatol. 2001; 11: 309-314PubMed Google Scholar, 9Olsen EA Messenger AG Shapiro J et al.Evaluation and treatment of male and female pattern hair loss.J Am Acad Dermatol. 2005; 52: 301-311Abstract Full Text Full Text PDF PubMed Scopus (185) Google Scholar Approximately 30% of white men are affected by age 30 years, at least 50% are affected by age 50 years, and 80% are affected by age 70 years.4Ellis JA Sinclair R Harrap SB Androgenetic alopecia: pathogenesis and potential for therapy.Expert Rev Mol Med. 2002; 4: 1-11Crossref Google Scholar The incidence of androgenetic alopecia also varies with race: white men are more likely to develop baldness than are men of Asian, American Indian, and African heritage. Also, the extent of hair loss often is more extensive in white men than in men of the previously mentioned other ethnicities.9Olsen EA Messenger AG Shapiro J et al.Evaluation and treatment of male and female pattern hair loss.J Am Acad Dermatol. 2005; 52: 301-311Abstract Full Text Full Text PDF PubMed Scopus (185) Google Scholar Most men with androgenetic alopecia experience psychosocial effects. Specifically, hair loss affects the balding individual's feelings of attractiveness and satisfaction with his physical appearance (body image) and can influence other persons’ perceptions of him.1Cash TF The psychosocial consequences of androgenetic alopecia: a review of the research literature.Br J Dermatol. 1999; 141: 398-405Crossref PubMed Scopus (182) Google Scholar2Cash TF The psychology of hair loss and its implications for patient care.Clin Dermatol. 2001; 19: 161-166Abstract Full Text Full Text PDF PubMed Scopus (120) Google Scholar The effects of male pattern baldness on self-image and others’ perceptions are not surprising in the context of the importance of hair in the sociocultural context.1Cash TF The psychosocial consequences of androgenetic alopecia: a review of the research literature.Br J Dermatol. 1999; 141: 398-405Crossref PubMed Scopus (182) Google Scholar2Cash TF The psychology of hair loss and its implications for patient care.Clin Dermatol. 2001; 19: 161-166Abstract Full Text Full Text PDF PubMed Scopus (120) Google Scholar Hair is an important determinant of physical attractiveness and a means of expressing individuality. Throughout history, abundant hair has symbolized vitality, health, and virility, whereas loss or removal of hair can connote subjugation, loss of individuality, impotency, and/or decrepitude. The negative effects of hair loss on body image have been observed in several studies of androgenetic alopecia in men.10Budd D Himmelberger D Rhodes T Cash TE Girman CJ The effects of hair loss in European men: a survey in four countries.Eur J Dermatol. 2000; 10: 122-127PubMed Google Scholar, 11Wells PA Willmoth T Russell RJ Does fortune favour the bald? psychological correlates of hair loss in males.Br J Psychol. 1995; 86: 337-344Crossref PubMed Scopus (52) Google Scholar, 12Cash TF The psychological effects of androgenetic alopecia in men.J Am Acad Dermatol. 1992; 26: 926-931Abstract Full Text PDF PubMed Scopus (191) Google Scholar, 13Gosselin C Hair loss, personality and attitudes.Pers Individ Dif. 1984; 5: 365-369Crossref Scopus (15) Google Scholar, 14van der Donk J Passchier J Dutree-Meulenberg RO Stolz E Verhage F Psychologic characteristics of men with alopecia androgenetica and their modification.Int J Dermatol. 1991; 30: 22-28Crossref PubMed Scopus (35) Google Scholar, 15Girman CJ Rhodes T Lilly FR et al.Effects of self-perceived hair loss in a community sample of men.Dermatology. 1998; 197: 223-229Crossref PubMed Scopus (65) Google Scholar, 16Goh CL A retrospective study on the characteristics of androgenetic alopecia among Asian races in the National Skin Centre, a tertiary dermatological referral centre in Singapore.Ann Acad Med Singapore. 2002; 31: 751-755PubMed Google Scholar Across studies, factors associated with a greater risk of hair loss-related psychological morbidity include young age, not being involved in a romantic relationship, strong reliance on physical appearance as a source of self-esteem, and having preexisting poor self-esteem.2Cash TF The psychology of hair loss and its implications for patient care.Clin Dermatol. 2001; 19: 161-166Abstract Full Text Full Text PDF PubMed Scopus (120) Google Scholar Besides affecting the balding man's self-image, hair loss can influence others’ perceptions of the balding individual. In studies comparing individuals’ initial impressions to sketches or photographs of balding compared with non-balding men, balding men were consistently rated as less physically and socially attractive, older, less likable, and less virile.17Roll S Verinis JS Stereotypes of scalp and facial hair as measured by the semantic differential.Psychol Rep. 1971; 28: 975-980Crossref Google Scholar, 18Moerman DE The meaning of baldness and implications for treatment.Clin Dermatol. 1988; 6: 89-92Abstract Full Text PDF PubMed Scopus (14) Google Scholar, 19Cash TF Losing hair, losing points? the effects of male pattern baldness on social impression formation.J Appl Soc Psychol. 1990; 20: 154-167Crossref Scopus (59) Google Scholar However, the degree to which these first impressions of balding men evolve over time has not been studied. Androgenetic alopecia is not known to be life threatening, but it can lead to physical harm. Hair protects against sunburn, cold, and mechanical injury. Because androgenetic alopecia in men involves loss of the hair's protection of the scalp from ultraviolet light, it may increase the risk of sunburn and the cellular damage that underlies skin cancer—possibilities that have not been established empirically. Normal hair growth occurs at the level of the hair follicle in a 3-phased cycle: (1) anagen, a 2- to 7-year active growth phase during which hair is produced continuously via the division and growth of specialized keratin-producing epidermal cells that surround a dermal papilla at the base of the hair follicle; (2) catagen, a 1- to 2-week transition and involution phase, during which the hair follicle contracts as a result of apoptosis and the hair bulb ascends toward the surface of the skin, loses its root sheaths that anchor the hair in place, and develops a club-shaped end to form a club hair (ie, a hair in the resting state); and (3) telogen, a 5- to 12-week resting phase during which the old club hair is shed. At the end of telogen, germinal cells of the hair follicle once again begin to grow to form a new hair bulb, which becomes the source of a new hair.4Ellis JA Sinclair R Harrap SB Androgenetic alopecia: pathogenesis and potential for therapy.Expert Rev Mol Med. 2002; 4: 1-11Crossref Google Scholar On average, in the normal scalp, at least 90% of hairs are in anagen, 1% are in catagen, and 9% are in telogen.20Whiting DA Male pattern hair loss: current understanding.Int J Dermatol. 1998; 37: 561-566Crossref PubMed Scopus (49) Google Scholar The basis of androgenetic alopecia in men is a progressive decrease in the density of terminal (thick and pigmented) hairs and a concurrent increase in density of vellus (short, fine, nonpigmented) hairs.20Whiting DA Male pattern hair loss: current understanding.Int J Dermatol. 1998; 37: 561-566Crossref PubMed Scopus (49) Google Scholar In effect, terminal hairs are turned off and are transformed into vellus hairs. This effect is attributed to miniaturization of the hair follicle, which is associated with a substantial reduction in hair diameter. Miniaturization may occur abruptly in 1 or a few hair cycles.21Whiting DA Possible mechanisms of miniaturization during androgenetic alopecia or pattern hair loss.J Am Acad Dermatol. 2001; 45: S81-S86Abstract Full Text Full Text PDF PubMed Scopus (120) Google Scholar In 1 illustrative study of biopsy specimens from 106 men with male pattern baldness and 44 nonbalding control subjects, the ratio of terminal to vellus hairs was 7:1 in the nonbalding scalp compared with 2:1 in the balding scalp.22Whiting DA Diagnostic and predictive value of horizontal sections of scalp biopsy specimens in male pattern androgenetic alopecia.J Am Acad Dermatol. 1993; 28: 755-763Abstract Full Text PDF PubMed Scopus (295) Google Scholar In male pattern baldness, the anagen phase shortens, and the telogen phase lengthens or remains the same so that hair length— which depends primarily on the duration of anagen— decreases.23Kaufman KD Androgens and alopecia.Mol Cell Endocrinol. 2002; 198: 89-95Crossref PubMed Scopus (161) Google Scholar Eventually, the hair does not reach the skin surface. Also, the time between the telogen stage and the anagen stage lengthens so that the number of scalp hairs decreases.4Ellis JA Sinclair R Harrap SB Androgenetic alopecia: pathogenesis and potential for therapy.Expert Rev Mol Med. 2002; 4: 1-11Crossref Google Scholar Although the mechanisms of these changes have not been established definitively, male pattern baldness is known to depend on androgens—in particular, the androgen dihydrotestosterone (DHT).23Kaufman KD Androgens and alopecia.Mol Cell Endocrinol. 2002; 198: 89-95Crossref PubMed Scopus (161) Google Scholar, 24Bartsch G Rittmaster RS Klocker H Dihydrotestosterone and the concept of 5α-reductase inhibition in human benign prostatic hyperplasia.Eur Urol. 2000; 37: 367-380Crossref PubMed Scopus (164) Google Scholar, 25Hamilton JB Male hormone stimulation is prerequisite and incitant in common baldness.Am J Anat. 1942; 71: 451-480Crossref Scopus (290) Google Scholar Dihydrotestosterone is synthesized from testosterone by 5α-reductase type 1 and type 2, lipophilic enzymes found on intracellular (nuclear) membranes.24Bartsch G Rittmaster RS Klocker H Dihydrotestosterone and the concept of 5α-reductase inhibition in human benign prostatic hyperplasia.Eur Urol. 2000; 37: 367-380Crossref PubMed Scopus (164) Google Scholar Type 2 5α-reductase, expressed in hair follicles and other androgen-dependent tissues such as the prostate gland, appears to be more important than type 1 in male pattern baldness. Several lines of circumstantial evidence support the crucial role of androgens—and DHT in particular—in male pattern baldness. First, this condition is not observed in eunuchs, who lack androgens; in individuals who lack functional androgen receptors; or in pseudohermaphrodites, who lack 5α-reductase.4Ellis JA Sinclair R Harrap SB Androgenetic alopecia: pathogenesis and potential for therapy.Expert Rev Mol Med. 2002; 4: 1-11Crossref Google Scholar25Hamilton JB Male hormone stimulation is prerequisite and incitant in common baldness.Am J Anat. 1942; 71: 451-480Crossref Scopus (290) Google Scholar, 26Griffin JE Wilson JD The androgen resistance syndromes: 5α-reductase deficiency, testicular feminization, and related disorders.in: Scriver CR Beaudet AL Sly WS Valle D 6th ed. The Metabolic Basis of Inherited Disease. Vol 2. McGraw-Hill, New York, NY1989: 1919-1944Google Scholar, 27Imperato-McGinley J Guerrero L Gautier T Peterson RE Steroid 5alpha-reductase deficiency in man: an inherited form of male pseudohermaphroditism.Science. 1974; 186: 1213-1215Crossref PubMed Scopus (1035) Google Scholar The absence of baldness in those lacking the gene for 5α-reductase type 2 suggests a necessary role for DHT. Second, the progression of androgenetic alopecia in men is halted coincident with castration among postpubertal men.5Feinstein R Androgenetic alopecia.Available at: www.emedicine.com/derm/topic21.htmGoogle Scholar Third, balding scalp contains excessive concentrations of 5α-reductase, DHT, and the androgen receptor.4Ellis JA Sinclair R Harrap SB Androgenetic alopecia: pathogenesis and potential for therapy.Expert Rev Mol Med. 2002; 4: 1-11Crossref Google Scholar28Schweikert HU Wilson JD Regulation of human hair growth by steroid hormones, II: androstenedione metabolism in isolated hairs.J Clin Endocrinol Metab. 1974; 39: 1012-1019Crossref PubMed Scopus (67) Google Scholar29Sawaya ME Price VH Different levels of 5alpha-reductase type I and II, aromatase, and androgen receptor in hair follicles of women and men with androgenetic alopecia.J Invest Dermatol. 1997; 109: 296-300Crossref PubMed Scopus (385) Google Scholar Finally, hair loss is mitigated or inhibited by finasteride, a medication that prevents the conversion of testosterone to DHT by selectively inhibiting the activity of 5α-reductase type 2.23Kaufman KD Androgens and alopecia.Mol Cell Endocrinol. 2002; 198: 89-95Crossref PubMed Scopus (161) Google Scholar Although the presence of androgens and a genetic predisposition are necessary for androgenetic alopecia in men, much about the pathophysiology of this condition remains to be elucidated. Androgenetic alopecia in men appears to be inherited, but the mode of inheritance is not yet understood. Hypothesized modes of inheritance include a single autosomal dominant gene, a single pair of sex-linked factors, a dominant gene with increased or variable penetrance in men, and polygenic inheritance.5Feinstein R Androgenetic alopecia.Available at: www.emedicine.com/derm/topic21.htmGoogle Scholar20Whiting DA Male pattern hair loss: current understanding.Int J Dermatol. 1998; 37: 561-566Crossref PubMed Scopus (49) Google Scholar A family history of androgenetic alopecia may be present on either side of the family; however, the absence of such a family history does not exclude the diagnosis. Male pattern baldness is diagnosed primarily on the basis of history and physical examination.5Feinstein R Androgenetic alopecia.Available at: www.emedicine.com/derm/topic21.htmGoogle Scholar Men with a history of progressive hair loss that follows the pattern defined by the Hamilton-Norwood scale are highly likely to have male pattern baldness. Biopsies can be used as diagnostic aids but seldom are required for diagnosis. Histopathologic changes characteristic of male pattern baldness include a progressive increase in the density of vellus hairs (vellus hair shafts are ≤0.03 mm in diameter and thinner than the follicle's inner root sheath), a decrease in the density of terminal hairs (terminal hair shafts are >0.03 mm in diameter and thicker than the follicle's inner root sheath), and a decrease in the ratio of terminal to vellus hair from 7:1 to approximately 2:1.5Feinstein R Androgenetic alopecia.Available at: www.emedicine.com/derm/topic21.htmGoogle Scholar9Olsen EA Messenger AG Shapiro J et al.Evaluation and treatment of male and female pattern hair loss.J Am Acad Dermatol. 2005; 52: 301-311Abstract Full Text Full Text PDF PubMed Scopus (185) Google Scholar These changes may be observed in the absence of an abnormal total number of hairs per unit area. Androgenetic alopecia is not considered to be an inflammatory condition; however, superficial perifollicular infiltrate may be present.5Feinstein R Androgenetic alopecia.Available at: www.emedicine.com/derm/topic21.htmGoogle Scholar The differential diagnosis of male pattern baldness includes diffuse alopecia areata—recurrent, nonscarring hair loss that may be associated with autoimmune disease. Unlike male pattern baldness, alopecia areata typically entails circumscribed and asymmetrical areas of baldness and can involve the eyebrows, face, and other body parts in addition to the scalp. A diagnosis of diffuse alopecia areata is suggested by findings of exclamation-point hairs, pitted nails, and/or a history of periodic regrowth of hair.5Feinstein R Androgenetic alopecia.Available at: www.emedicine.com/derm/topic21.htmGoogle Scholar Alopecia areata, which is much less common than male pattern baldness, reportedly affects 1.7% of the US population by the age of 50 years.30Safavi KH Muller SA Suman VJ Moshell AN Melton III, LJ Incidence of alopecia areata in Olmsted County, Minnesota, 1975 through 1989.Mayo Clin Proc. 1995; 70: 628-633Abstract Full Text Full Text PDF PubMed Scopus (449) Google Scholar Other differential diagnoses include acute and chronic telogen effluvium (ie, excessive shedding of normal club hairs; may be idiopathic or associated with iron deficiency, papulosquamous scalp diseases, or stressors) and early cicatricial alopecia (ie, hair loss arising from the destruction of hair follicles by scarring from processes such as trauma, burns, lupus erythematosus, or lichen planopilaris). Management of male pattern baldness involves obtaining a medical history, performing a physical examination, assessing changes in scalp hair in the context of the age and occupation of the individual, assessing the importance of hair loss to the patient, and working with the patient to determine the best treatment. Options for managing androgenetic alopecia in men include doing nothing and accepting the cosmetic outcome (the “wait and see” approach), pharmacotherapy, hair transplantation, and cosmetic aids. Hair loss is progressive and does not improve or reverse without treatment. Two US Food and Drug Administration-approved pharmacotherapies—minoxidil and finasteride—are available for treatment of male pattern baldness. These medications, which differ in mechanism of action and route of administration, are given as monotherapy or as combination therapy, although few clinical studies of combination therapy have been published to date. These drugs often are prescribed for patients undergoing hair-restoration surgery to reduce the amount of transplanted hair required to meet the patient's objectives and to help the patient maintain a relatively consistent and natural appearance. Although minoxidil and finasteride both retard or stop hair loss and stimulate some hair regrowth, neither medication restores all lost hair or reverses complete baldness. No well-controlled study comparing minoxidil and finasteride has been published to date. In a randomized study in which 99 patients treated with finasteride or minoxidil were monitored for up to 24 months, both agents appeared to be similarly effective for stopping the progression of androgenetic alopecia.31Saraswat A Kumar B Minoxidil vs finasteride in the treatment of men with androgenetic alopecia [letter].Arch Dermatol. 2003; 139: 1219-1221Crossref PubMed Scopus (36) Google Scholar Minoxidil. Initially introduced in the 1970s as a systemic treatment of hypertension, minoxidil now is marketed also as topical 2% and 5% solutions for androgenetic alopecia in men and women.32Messenger AG Rundegren J Minoxidil: mechanisms of action on hair growth.Br J Dermatol. 2004; 150: 186-194Crossref PubMed Scopus (377) Google Scholar Minoxidil is a potassium channel opener, and its mechanism of action in male pattern baldness is unknown. Minoxidil appears to increase the duration of the anagen phase, and its angiogenic effects reverse miniaturization of hair follicles. In placebo-controlled clinical studies, minoxidil slowed hair loss and increased hair density, measured by target-area hair counts, expert panel review of global photographs, and hair weight.33Olsen EA Dunlap FE Funicella T et al.A randomized clinical trial of 5% topical minoxidil versus 2% topical minoxidil and placebo in the treatment of androgenetic alopecia in men.J Am Acad Dermatol. 2002; 47: 377-385Abstract Full Text Full Text PDF PubMed Scopus (249) Google Scholar34Price VH Menefee E Strauss PC Changes in hair weight and hair count in men with androgenetic alopecia, after application of 5% and 2% topical minoxidil, placebo, or no treatment.J Am Acad Dermatol. 1999; 41: 717-721Abstract Full Text Full Text PDF PubMed Scopus (113) Google Scholar Growth of hair appears to peak approximately 4 months after initiation of therapy. The 5% solution is associated with an earlier and more robust response than the 2% solution for male pattern baldness. In a randomized, double-blind, placebo-controlled study in which patients applied 5% minoxidil (n=157), 2% minoxidil (n=158), or placebo (n=78) twice daily, hair density improved more with active treatment than placebo. In addition, androgenetic alopecia improved more with the 5% solution compared with the 2% solution, reflected in target-area hair count increases after 48 weeks of treatment (18.6/cm2 for the 5% solution, 12.7/cm2 for the 2% solution, and 3.9/cm2 for placebo) and in expert panel review of global photographs after 1 year (increased growth in 57.9% of men with the 5% solution, 40.8% of men with the 2% solution, and 23.2% of men with placebo).33Olsen EA Dunlap FE Funicella T et al.A randomized clinical trial of 5% topical minoxidil versus 2% topical minoxidil and placebo in the treatment of androgenetic alopecia in men.J Am Acad Dermatol. 2002; 47: 377-385Abstract Full Text Full Text PDF PubMed Scopus (249) Google Scholar To maximize efficacy, minoxidil should be applied evenly to the entire affected area of the scalp. Patients should avoid wetting the scalp for at least 1 hour after minoxidil administration to allow the drug sufficient time to be absorbed; also, patients should apply minoxidil before any use of hair gel or hair spray so that absorption is not affected.9Olsen EA Messenger AG Shapiro J et al.Evaluation and treatment of male and female pattern hair loss.J Am Acad Dermatol. 2005; 52: 301-311Abstract Full Text Full Text PDF PubMed Scopus (185) Google Scholar Minoxidil must be applied daily to maintain effectiveness. If treatment is discontinued over a period of a few months, the scalp appears to revert to the state that it would have been in without pharmacotherapy.35Olsen EA Weiner MS Topical minoxidil in male pattern baldness: effects of discontinuation of treatment.J Am Acad Dermatol. 1987; 17: 97-101Abstract Full Text PDF PubMed Scopus (40) Google Scholar Generally, minoxidil is well tolerated with long-term daily use. Adverse events are primarily dermatologic and include irritant contact dermatitis and, less often, allergic contact dermatitis.36Friedman ES Friedman PM Cohen DE Washenik K Allergic contact dermatitis to topical minoxidil solution: etiology and treatment.J Am Acad Dermatol. 2002; 46: 309-312Abstract Full Text Full Text PDF PubMed Scopus (117) Google Scholar Transient and self-limiting telogen effluvium may begin approximately 3 to 5 weeks after initiation of treatment. Patients should be informed about the possibility of temporary telogen effluvium and advised to continue treatment should it occur. Finasteride. Initially introduced in a 5-mg dose for treatment of benign prostatic hyperplasia, finasteride is now marketed in a 1-mg dose for treatment of male pattern baldness. Finasteride selectively inhibits the type 2 5α-reductase isoenzyme responsible for converting testosterone to DHT, the putative hormonal modulator of androgenetic alopecia in men. Finasteride reduces serum and scalp DHT concentrations by approximately 60% to 70%.37Drake L Hordinsky M Fiedler V et al.The effects of finasteride on scalp skin and serum androgen levels in men with androgenetic alopecia.J Am Acad Dermatol. 1999; 41: 550-554Abstract Full Text PDF PubMed Scopus (167) Google Scholar Finasteride
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