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Hair loss, Balding, and Alopecia

Two decades ago hair growth promoters were nonexistent. From a medical perspective, little could be offered to patients with common hair loss problems. Today there are new classes of hair growth promoters with proven efficacy.

A hair growth-promoting agent may prolong the anagen phase or increase matrix girth by influencing hair loss. For example, in androgenetic alopecia, drug targets may include steroid receptors, steroid metabolizing enzymes, growth factors, or cytokines.


Hair growth promotors can be classified according to their mode of action and the condition being treated.


Knowledge of the pathophysiology of androgenetic alopecia (AGA) is essential in understanding the mechanism of action of present therapeutic agents. AGA requires both genetic and hormonal factors. The inheritance pattern appears to be autosomal dominant, although it has also been described as polygenic with heritability from either parent. The clinical pattern of hair loss.

Androgen Receptor Proteins

Androgen receptor proteins (ARPs) are present within the outer root sheath and dermal papilla fibroblasts. Receptor levels were found to be 30% greater in the balding frontal hair follicles.

Steroid-Metabolizing Enzymes: 5 alpha-Reductase and Aromatase

Intracellular androgen metabolism is one key factor in AGA, as exhibited by differential androgen-metabolizing enzyme activity in balding versus nonbalding scalp.

Therapeutic Strategies

The aim of therapy is to reverse and/or stabilize the miniaturization process. Currently, this can be accomplished with hormone modifiers or biologic response modifiers.

Hormone Modifiers
  1. Androgen Blockade.
    a) 5 alpha-Reductase Inhibitors.
Finasteride Propecia.

Finasteride is a synthetic 4-azasteroid compound that is a specific inhibitor of type 2 5 alpha-reductase, an intracellular enzyme that converts T into DHT. By inhibiting type 2 5 alpha-reductase, finasteride blocks the peripheral conversion of T to DHT, resulting in significant

Finasteride at a dose of 1 mg/day was approved for use in men with AGA (male pattern hair loss) in the U.S. by the FDA in late 2006. Continued daily use of 1 mg oral finasteride is needed for sustained benefit. If treatment is stopped, the benefits are lost as expected since this treatment does not affect the genetic basis of the condition.

A male fetus in utero must not be exposed to finasteride, and for this reason women who are or may potentially be pregnant should not take finasteride or handle crushed or broken tablets. If a pregnant

Cyproterone Acetate.

CPA is a potent androgen receptor antagonist as well as a potent progestin. CPA is available in Europe and Canada, although it is not approved in the United States. CPA is most effective in hirsutism and in acne but is not as effective for AGA in women. For the treatment of AGA in women, 50 to 100 mg per day of CPA taken on day 5 to 14 of the menstrual cycle can be used in combination with an oral contraceptive such as Demulen 1/35. There are no large controlled clinical studies in AGA with CPA. It appears to


Spironolactone is an aldosterone antagonist that has mild antiandrogenic effects. It is a competitive

2. Estrogen Mediated.

Estrogens increase levels of sex hormone binding globulin (SHBG), thereby reducing circulating free T. They also inhibit secretion of leutinizing hormone-releasing hormone (LH-RH) by the

Biologic Response Modifiers

Biologic response modifiers may include cell mitogens, vasodilators, promotors of angiogenesis,


Minoxidil is a piperidinopyrimidine derivative that acts as a smooth muscle vasodilator in the treatment of hypertension. The mechanism of action of minoxidil on hair growth promotion is still unclear. It does not have any hormonal effects or immunosuppressant effects; rather, it has direct mitogenic

Minoxidil sulfate (MS) appears to be the active metabolite responsible for hair growth stimulation.

Topical minoxidil side effects are mainly dermatologic and include an irritant effect (dryness, itching, erythema) primarily due to propylene glycol or to the formulated topical solution. Occasionally, minoxidil itself causes allergic contact dermatitis. Incidence of irritancy is approximately 7% with the


Retinoids may be important for changing the status of regressing follicles. Tretinoin, all- trans-retinoic acid, is a biologic response modifier with many pharmacologic and physiologic effects. It is a potent cell mitogen that promotes and regulates epithelial cell growth and differentiation. It promotes angiogenesis and increases percutaneous absorption by affecting cell membrane fluidity and lipid composition of membranes. There is increased cytosol retinoic acid-binding protein in follicular cells compared to adjacent

Action Plan for Men with Androgenetic Alopecia

The strategy for medical treatment of male AGA is based on the following factors: presence of miniaturized hairs, extent of hair loss, and patient's preferences for systemic versus topical agents. For

For Male Patients with Minimal to Moderate Hair Loss

Therapeutic options include topical minoxidil 2% and 5% solutions, or oral finasteride 1 mg tablet

For Male Patients with Advanced AGA

Current medical modalities are of little benefit for men with a completely or almost completely bald scalp. Surgical approaches (i.e., hair transplantation with possible scalp reductions) are

Action Plan for Women with Androgenetic Alopecia

The strategy for treating women with AGA depends on the presence of miniaturized hairs and extent of the hair thinning (Fig. 4) (Figure Not Available) . For women with Ludwig stage I and II, topical