Zoe Diana Draelos, MD

Q: What is postmenopausal dry scalp, and does it cause female pattern alopecia?

Postmenopausal dry scale and female pattern alopecia are common findings in women who see a dermatologist for hair and scalp issues. Remember, menopause occurs due to lack of estrogen, the hormone responsible for encouraging sebum production and scalp hair growth. This loss of estrogen from declining ovarian function may uncover female pattern hair loss, but the hair loss is unrelated to decreases in scalp sebum production.

However, the reduced sebum production does cause dry scalp and an accompanying decrease in scalp exfoliation, which may or may not be associated with itching. The scalp scale typically appears as fine, powdery white flakes; they do not respond to traditional seborrheic dermatitis treatments because postmenopausal dry scalp is not related to fungal overgrowth in the scalp microbiome. Thus, the removal of Malassezia species produces no improvement. There is also no inflammation, as evidenced by the white scale that is not serum stained yellow—unless scratching occurs as a response to itching—so topical corticosteroids are of minimal benefit.

The best treatment for this condition is to remove the scale and moisturize the scalp. Shampoos containing salicylic acid are most useful and should be applied with vigorous scrubbing of the scalp to dislodge the skin scale. Shampooing and rinsing should be followed immediately with a dimethicone-containing instant conditioner for dry hair. Next, before the hair dries, a product with argan oil and dimethicone should be applied. The hair oil should be dispensed into the palm of one hand, and the fingertips of the opposite hand should be rubbed into the oil and then into the scalp, avoiding the hair. The oil may reduce hair volume if intentionally rubbed into the entire length of the hair.

The procedure should be repeated with the opposite palm and fingertips until the entire scalp has been oiled. If shampooing is infrequent and the scalp becomes dry again, it can be oiled between shampoos.

Some information posted on the internet erroneously suggests that hair oils cause further alopecia by “clogging” the follicular ostia. That is not possible—if it were true, hair would not grow due to the presence of sebum that leaves the sebaceous gland and exits the follicular ostia to form a film over the scalp skin.

Removing the scalp skin scale is important in alleviating postmenopausal pruritus because retained scale provides a surface on which sebum, sweat, and bacteria can collect. Usually, the itching will decrease once the scalp has been exfoliated. If using a shampoo with salicylic acid does not remove the scale, a salicylic acid scalp solution can be applied at bedtime and washed out the following day. If the scalp pruritus does not respond, a prescription topical corticosteroid may be indicated.

Q: Do dandruff shampoos encourage hair loss?


The internet is full of posts claiming that dandruff shampoos cause hair loss. It is impossible for a typical shampoo following the dandruff monograph to induce hair loss. The shampoo does not penetrate to the level of the follicle and therefore cannot affect hair growth.

However, the presence of dandruff can indirectly discourage growth. Many people with dandruff experience scalp itching, which varies with the severity of the dandruff. This itching leads to scratching that damages the hair cuticle, reducing the strength of the hair and eventually shearing off the hair fiber, which results in hair loss. Thus, it is possible that patients who have dandruff will experience increased hair loss but not due to the dandruff shampoo; rather, scalp scratching can lead to inadvertent hair scratching and subsequent hair loss.

Q: Are scalp-camouflaging products damaging to the hair and scalp?


Many new camouflaging products on the market increase the appearance of hair fullness and camouflage scalp skin. These products are powders or short hair fibers, usually of animal origin. The particles are charged with static electricity so that they adhere to the native hairs and/or scalp. They may be further held in place with a hair spray–type product. These camouflaging products may be used safely by both men and women and are removed by shampooing. They do not damage the scalp or hair but should not be a deterrent to good scalp hygiene.

Articles

In this month's Cosmetic Conundrums column, Dermatology Times® Chief Medical Editor Zoe Diana Draelos, MD, explores scalp flaking causes and treatments.

Get the Facts on Flaking

Q: Why are cosmetic moisturizers and topical drug vehicles so different? Is it the ingredients?

That is an excellent question. Dermatologists might think a pharmaceutical company could take a moisturizer and simply add any ingredient to make a new topical drug, [thereby improving texture]. Regrettably, this is not possible. The number of FDA-approved ingredients used in drug vehicles is much smaller than the unlimited ingredient list available to cosmetic formulators. The FDA requires new vehicle ingredients to undergo full nonclinical testing, including reproduction and fertility testing and 2-year carcinogenicity studies in 2 animal species. Also, the additional cost of completing this testing can be $25 million. Most pharmaceutical companies do not use ingredients that are not on the FDA Inactive Ingredients Database in their products. Thus, innovation in the topical treatment of skin occurs almost exclusively within the field of cosmetics rather than medical dermatology.

Q: How does the limitation of ingredients in pharmaceutical vehicles affect dermatologic drugs?

One key area where FDA limitations on drug vehicle ingredient selection presents challenges is in the realm of emulsifiers. Emulsifiers are very important in topical drugs to prevent hydrophobic (water-hating) emollients suspended in moisturizing creams and lotions from separating a few days after manufacture. However, emulsifiers are basically detergents, such as sodium alkyl sulfates, and can efficiently extract important epidermal intercellular lipids, compromising the skin barrier.

In 1957, topical pharmaceutical creams were emulsified with beeswax, polyoxyl esters, or sodium alkyl sulfates. Forty years later, 81 FDA-approved prescription topical creams were formulated with one of these 3 classes of emulsifiers. A recent search of the FDA Inactive Ingredient Database confirmed that the emulsifiers used in over-the-counter dermatologist-recommended cleansers and moisturizers (Cetaphil, Galderma Laboratories and CeraVe, L’Oréal) are not used as emulsifiers in FDA-approved prescription creams. Thus, modern ultra-gentle moisturizing cream vehicles are not used in pharmaceuticals presently.

Q: How do penetration enhancers used in most topical pharmaceuticals affect the skin?

Many topical drugs contain alcohol, propylene glycol, dimethyl sulfoxide, sodium lauryl sulfate, or other skin penetration enhancers to overcome barrier properties of the skin and deliver higher therapeutic concentrations of drugs. This damage to the skin barrier is counterproductive, especially in conditions such as atopic dermatitis, where cumulative barrier damage from continued exposure to penetration enhancers may inhibit disease resolution.

Many topical medications are emollient formulations containing hydrophilic occlusive agents such as petrolatum, waxes, oils, or silicones that coat the skin surface and trap water in the stratum corneum. The most aesthetically pleasing emollient formulations are creams and lotions, which also contain significant amounts of water. These formulations require emulsifiers, such as sodium cetostearyl sulfate, the emulsifier used in pimecrolimus cream that also functions as a detergent mixing and disorganizing the stratum corneum lipids. The defective skin barrier of patients with atopic dermatitis makes them more vulnerable to the detergency effects of emulsifiers introduced into the stratum corneum. The defective skin barrier is the challenge formulators face when designing penetration-enhanced topical pharmaceuticals.

Q: What is the best way to conquer irritation from topical pharmaceutical emulsifiers?

Until more modern dermatologic topical formulations are available, irritation from topical pharmaceutical emulsifiers can be overcome somewhat by using a modern cosmetic moisturizer, such as Cetaphil and CeraVe cream. The topical drug should be rubbed in thoroughly until it creates a thin film and is dried down on the skin surface. This process usually takes 10 to 15 minutes, depending on the drug formulation. The moisturizing cream can then be applied on top to mitigate damage induced by emulsifiers. In the future, hopefully, newer, more cosmetically elegant topical formulation may achieve this in one step.

In this month's Dermatology Times Cosmetic Conundrums column, the Chief Medical Editor Zoe Diana Draelos, MD, details the difference between cosmetic moisturizers and pharmaceutical vehicles.