Doctors should provide evidence-based information about emollients for patients of African origin, since both hyperpigmentation and lichenification are different for black skin types than white or Asian skin types.

When it comes to emollients for xerosis, simpler is often better.

Prof Pascal Niamba (from Burkina Faso) and Dr Alain Delarue (medical director, Pierre Fabre) are both experts in the field of dermatology. They recently presented their findings at an event in Cape Town. Medical Chronicle’s editor, Claire Rush was there to document the evening.

Skin hydration is often associated with notions of comfort, wellbeing and health. Xerosis or dehydration of the skin is a loss or lack of water in the stratum corneum. Conversely, hydration is all biological phenomena (cellular or biochemical) that contribute to the maintenance of the quantity of water necessary for the proper functioning and cohesion of keratinocytes.

The skin has functions that relate to protection, sensation, absorption, secretion, metabolism and thermoregulation.

The corneum layer is the most superficial layer, composed of flattened anucleate horny cells. It is a skin barrier that protects the skin against dehydration and external aggressions. 

Why should the skin be hydrated?

Natural regulation of skin hydration

The hydration of the epidermis depends on the balance between losses and intakes of the skin barrier. The lipid cement, cell membrane and hydrolipidic film inhibit water evaporation. Natural moisturising factors attract and retain water inside cells. This consists of amino acids, urea, organic acids, glycerol, mineral salts and simple sugars.

Hydration is ensured by the hydrolipidic barrier formed by corneocytes filled with keratin and the lipid cement of the stratum corneum.

But this barrier is not impenetrable; it can let in water.

Water is constantly added to the skin by the blood circulation in the dermis, then by diffusion towards the epidermis.

The skin continually loses water by perspiration, or by evaporation.

Skin dehydration aetiology

Genetic causes include environmental factors such as heat and dry air circulation. Other factors are unsuitable care including surfactants and too frequent cleaning not compensated by the application of protective creams.

Another enabler is ageing. The decrease in sebum production, other functions impaired with age and general dehydration of the body.

Skin hydration is a biological process that is dependent on molecular complexes, the environment, nutritional status, good hygiene, water soap + emollient and eradication of bad practices.

Clinical signs include itching, xerosis, erythema, oedema, papule dander, excoriations ointment and lichenification crusts.

Unusual modified clinical signs include oedema, oozing, excoriations and xerosis.

But two signs are not the same on white skin and brown skin:

On white skin, pink or dark pink thickening, superficial grid dryness. On black skin, lichenification made of small papules isolated from each other.

Pigmentation disorders

These are disorders of post-inflammatory pigmentation (dyschromia) secondary to skin diseases such as atopic dermatitis (AD) are particularly badly experienced by patients (and parents) of children affected.

Objective signs of skin dehydration

  • Rough, scaly appearance
  • Thickening of the stratum corneum
  • Stiffness, lack of elasticity
  • Irritation, reddening
  • Fissures, cracks
  • Low hydration (corneometry)
  • High water loss (TEWL)

Subjective symptoms of skin dehydration

  • Itching, burning sensation, tightness
  • Prickling (face, extremities)
  • Intolerance to topical applications
  • Hypersensitivity to the climate

The choice of moisturising agent is highly dependent on individual preference.

Formulations come in a variety of delivery systems:  creams, ointments, oils, gels, and lotions. Most ointments don’t contain preservatives but are too greasy for some patients.  Lotions have a higher water content that can evaporate, which is less ideal if there is significant xerosis.

The ideal agent should be safe, effective, inexpensive, and free of additives, fragrances, perfumes, and other potentially sensitising agents.

How to choose a treatment adapted for xeroses?

Occlusive effect: protective film

  • Such as paraffin oil and petrolatum

This has the following functions:

  • Prevents water loss
  • Restores barrier function
  • Decreases external aggressions
  • Immediate effect

Softening effect: hydration

  • Such as glycerol and urea

Glycerol promotes mobilisation of internal water through AQP3 (Aquaporin 3), capture of external water (environment and sweating) and storage of water in the stratum cornea for prolonged action.

There are large differences between emollients of different formulations. Not all emollients exert a positive effect on the skin barrier.

Atopic dermatitis

This condition entails chronic, inflammatory and itchy dermatosis. It evolves with flares and remission. It affects mainly children, but is also seen in adults.

In the NHS/NICE Clinical Guideline 2007 (UK) for atopic eczema in children up to the age of 12 years, emollients are included for xerosis: No eczema, mild AD, moderate AD and severe AD.

The speakers emphasised that application of moisturisers should be an integral part of the treatment of patients with AD as there is strong evidence that their use can reduce disease severity and the need for pharmacologic intervention.

According to Wollenberg A et al (2018), emollients form part of the baseline, basic therapy. Long-term emollient therapy improves xerosis in children with atopic dermatitis.

Xerosis

There has been significant improvement in AD patients, increasing with time.

For responders, stopping the emollient leads to worsening of xerosis. For non-responders, introduction or maintenance of the emollient after 28 days improves the condition.

Emollient use has the following results:

  • Decrease of severity of AD symptoms (in evaluation by patients or doctors)
  • Prevention of flares
  • Sparing of topical corticosteroids (TCS)
  • Decrease of colonisation by S. aureus
  • Improvement of QoL
  • Balance of microbiota

Prevention of flares and TCS sparing

In 173 children <1 year with AD (SCORAD: 20-70) with moderately potent or a potent TCS and moderately potent or a potent TCS + emollient: At D42: 7.5 % moderately potent TCS (4.66 vs 4.91 g), 42% potent TCS (8.56 vs 14.7g).

A randomised controlled trial compared using a soap bar alone two times a day versus soap bar and emollient milk in children six months to 12 years old, with moderate AD (SCORAD >35).

Results: D0–D28: Decrease in TCS consumption – 35% (24.5 vs 38g). D29–D56 showed similar consumptions in both groups (with a greater SCORAD reduction in the treated group).

Preventive use of emollients changes skin microbiota

In a randomised prospective trial, new-borns with family history of AD had treatment for six months:

  • Emollients (n=11)
  • No emollients (n=12)

Tests on cheeks, volar forearms, dorsal forearms: bacterial 16S ribosomal RNA gene sequences. 

In the emollient group:

  • Higher proportion of S. salivarius (commensal)
  • Higher bacterial diversity

Emollients in uremic xerosis

A multicentric, randomised, double-blind, intra-individual (left versus right comparison) assessed 99 patients with moderate to severe uremic xerosis. After seven days of treatment: Responder = decrease of at least two points at xerosis score.

There was a 75% reduction of uremic pruritus after 56 days.

In terms of improvement of QoL after 56 days:

  • Patients were very satisfied to satisfied
  • Efficacy was 84%
  • Ease of use was 93%
  • Local tolerability was 93%

Emollients in diabetic foot (skin hydration)

In a 28-day, double-blind RCT versus vehicle with 57 diabetic subjects (52% female) with a history of diabetes being11.6 ± 8.2 years and associated neuropathy: 47%.

There was significant improvement for D-Squame and relief parameters. Greater patient satisfaction (p=0.022) and the wish to continue was 44% vs 29%).

How much to apply in AD?

It is generally thought that liberal and frequent reapplication is necessary.

HOW MUCH? HOW OFTEN? WHEN? WHERE? WHICH?
250g / week

for a child

600g / week

for an adult

Each day

Use in

Periods out

of flare and

during the

flare

Out of flares:

2 applications / day

-Morning

-Evening

 

During the flares:

1 application / day

-Morning

Out of lesions

Out of inflammation

Whole body

Having 2 effects

on epidermal

barrier:

-occlusive effect

-hydrating effect

 

 

Conclusion

The choice of a moisturising agent is highly dependent on individual preference. The ideal agent should be safe (free of additives, fragrances, perfumes, and other potentially sensitising agents).

It should be effective and evidence-based. An inexpensive product is practical for long-term treatments.

Choosing an appropriate emollient would improve acceptability and adherence to treatment. The physician’s recommendation is the primary consideration for patients when selecting a moisturiser or emollient. Doctors should provide evidence-based information about these emollients.