3 - Alpha-Hydroxy Acids Flashcards
Alpha-hydroxy acids (AHA) are a family of carboxylic acids with a hydroxyl group on the adjacent (or alpha) carbon
True
The AHA are:
(1) Glycolic acid - 2 carbons
(2) Lactic acid - 3 carbons
(3) Malic acid - 4 carbons
(4) Tartaric acid - 4 carbons
(5) Citric acid - 6 carbons
(6) Mandelic acid - 8 carbons
True (Glycolic acid and lactic acid are most commonly used)
The most commonly used AHA are:
(1) Glycolic acid
(2) Lactic acid
True
The higher molecular weight AHA such as Malic acid, tartaric acid, citric acid and Mandelic acid are not as widely used as these do not penetrate the stratum corneum as well as Glycolic acid and Lactic acid
True
Glycolic acid is derived from sugar cane
True
Lactic acid is derived from milk
True
The AHA used in practice are chemically synthesised
True
Glycolic acid is the smallest of the AHA (2 carbon molecule)
True
Glycolic acid is stable
True
Glycolic acid is colourless
True
Glycolic acid is odourless
True
Glycolic acid is water-soluble
True
Glycolic acid is non-toxic if ingested
True
Lactic acid is a 3 carbon AHA molecule which can exist in several isomeric forms
True
Polyhydroxy acids (PHA) are also a family of carboxylic acids but are longer carboxylic acids with >2 hydroxyl groups, 1 of which is attached to the (alpha) carbon
True (owing to their larger size, PHA have a slower rate of absorption into the skin compared to AHA)
Owing to their larger size, PHA have a slower rate of absorption into the skin compared to AHA
True
The principal PHA are:
(1) gluconolactone
(2) galactose
(3) lactobionic acid - polymer of galactose and gluconolactone derived from lactose in cow’s milk
True
The PHA (galactose, gluconolactone, and lactobionic acid) contain more hydroxyl groups than AHA, therefore allowing them to bind more water than the smaller AHA
True (thus PHA have greater humectant and moisturising properties)
All AHA cause detachment of keratinocytes by promoting the degradation of corneodesmosomes, thereby accelerating stratum corneum turnover (epidermal effects)
True
AHA are hypothesised to decrease the calcium ion concentration in the epidermis, causing loss of calcium ions from the cell junctions which lead to desquamation, thereby promoting keratinocyte proliferation and retard keratinocyte differentiation (epidermal effects)
True (hence giving the skin a more youthful appearance)
When AHA are consistently applied to rough and dry skin, regulation of keratinisation yields a smoother less scaly surface (epidermal effects)
True
Desquamation from follicular orifices induced by AHA cleanses the pores and prevents follicular occlusion (epidermal effects)
True
Patients using AHA products note the control of dry skin, ichthyosis and acne, as well as disappearance of solar lentigines (epidermal effects)
True (regulation of keratinisation and desquamation)
Higher concentration AHA products not only diminish corneocyte cohesion, but can also reduce melanin synthesis (epidermal effects)
True (therefore this melanin inhibitory effect combined with epidermal remodelling/regulation of keratinisation makes the higher concentration AHA potentially useful for treating seborrhoeic keratoses, AKs, verrucae and facial rhytides)
AHA causes:
(1) epidermal effects
(2) dermal effects
True
Long term use of AHA produces measurable dermal effects including increased glycosaminoglycans, increased collagen density, disbursement of melanin, and improved quality of elastic fibres (improved dermal ground substances)
True
Long term use of AHA causes increase thickness of the viable epidermis and papillary dermis, without any inflammation (epidermal and dermal effects)
True
AHA causes the increase in type I collagen and intercellular ground substances, namely hyaluronic acid, that leads to increased dermal hydration and thickness and provides an aqueous environment for the diffusion of nutrients and toxins (dermal effects)
True
AHA causes a decrease in overall photodamage (epidermal and dermal effects)
True
AHA does not cause increase in dermal vasculature
True (this is in contrast to topical retinoids)
AHA may reverse the epidermal atrophic changes that are associated with topical corticosteroid treatment
True
PHA (gluconolactone, galactose, lactobionic acid) have a similar mechanism of action to AHA (Glycolic acid, lactic acid) as well as additional humectant and moisturising properties
True (PHA have more hydroxyl groups than AHA and therefore a greater water binding capacity)
PHA (gluconolactone, galactose, lactobionic acid) treated skin shows less transepidermal water loss and less skin irritation than AHA (Glycolic acid, lactic acid) treated skin when challenged with sodium lauryl sulfate
True (PHA have more hydroxyl groups than AHA and therefore a greater water binding capacity)
PHA (gluconolactone, galactose, lactobionic acid) are used in many cosmetic formulations because they produce similar results to AHA and are tolerated by more sensitive skin types
True (PHA have more hydroxyl groups than AHA and therefore a greater water binding capacity)
AHA produce stratum corneum response only with the following:
(1) <10% AHA application daily with pH >3
(2) high % AHA in short exposure times with pH <3
True
AHA produces both epidermal and dermal response with the following:
(1) single exposure to un-neutralised high % AHA
(2) repeated exposures to low % AHA with pH<3
(3) repeated exposures to high % AHA with pH>3
True
AHA is used in xerosis
True (reversal of hyperkeratosis, increase in viable epidermis and dermal thickness)
AHA is used in ichthyosis
True (reversal of hyperkeratosis, increase in viable epidermis and dermal thickness)
AHA is used in rhytides
True (increased production of collagen and intercellular ground substances, causing reversal of the epidermal and dermal markers of photoaging)
AHA is used in dermatoheliosis
True (increased production of collagen and intercellular ground substances, causing reversal of the epidermal and dermal markers of photoaging)