3 - Alpha-Hydroxy Acids Flashcards
(100 cards)
1
Q
Alpha-hydroxy acids (AHA) are a family of carboxylic acids with a hydroxyl group on the adjacent (or alpha) carbon
A
True
2
Q
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
A
True (Glycolic acid and lactic acid are most commonly used)
3
Q
The most commonly used AHA are:
(1) Glycolic acid
(2) Lactic acid
A
True
4
Q
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
A
True
5
Q
Glycolic acid is derived from sugar cane
A
True
6
Q
Lactic acid is derived from milk
A
True
7
Q
The AHA used in practice are chemically synthesised
A
True
8
Q
Glycolic acid is the smallest of the AHA (2 carbon molecule)
A
True
9
Q
Glycolic acid is stable
A
True
10
Q
Glycolic acid is colourless
A
True
11
Q
Glycolic acid is odourless
A
True
12
Q
Glycolic acid is water-soluble
A
True
13
Q
Glycolic acid is non-toxic if ingested
A
True
14
Q
Lactic acid is a 3 carbon AHA molecule which can exist in several isomeric forms
A
True
15
Q
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
A
True (owing to their larger size, PHA have a slower rate of absorption into the skin compared to AHA)
16
Q
Owing to their larger size, PHA have a slower rate of absorption into the skin compared to AHA
A
True
17
Q
The principal PHA are:
(1) gluconolactone
(2) galactose
(3) lactobionic acid - polymer of galactose and gluconolactone derived from lactose in cow’s milk
A
True
18
Q
The PHA (galactose, gluconolactone, and lactobionic acid) contain more hydroxyl groups than AHA, therefore allowing them to bind more water than the smaller AHA
A
True (thus PHA have greater humectant and moisturising properties)
19
Q
All AHA cause detachment of keratinocytes by promoting the degradation of corneodesmosomes, thereby accelerating stratum corneum turnover (epidermal effects)
A
True
20
Q
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)
A
True (hence giving the skin a more youthful appearance)
21
Q
When AHA are consistently applied to rough and dry skin, regulation of keratinisation yields a smoother less scaly surface (epidermal effects)
A
True
22
Q
Desquamation from follicular orifices induced by AHA cleanses the pores and prevents follicular occlusion (epidermal effects)
A
True
23
Q
Patients using AHA products note the control of dry skin, ichthyosis and acne, as well as disappearance of solar lentigines (epidermal effects)
A
True (regulation of keratinisation and desquamation)
24
Q
Higher concentration AHA products not only diminish corneocyte cohesion, but can also reduce melanin synthesis (epidermal effects)
A
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)
25
AHA causes:
(1) epidermal effects
(2) dermal effects
True
26
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
27
Long term use of AHA causes increase thickness of the viable epidermis and papillary dermis, without any inflammation (epidermal and dermal effects)
True
28
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
29
AHA causes a decrease in overall photodamage (epidermal and dermal effects)
True
30
AHA does not cause increase in dermal vasculature
True (this is in contrast to topical retinoids)
31
AHA may reverse the epidermal atrophic changes that are associated with topical corticosteroid treatment
True
32
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)
33
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)
34
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)
35
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
36
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
37
AHA is used in xerosis
True (reversal of hyperkeratosis, increase in viable epidermis and dermal thickness)
38
AHA is used in ichthyosis
True (reversal of hyperkeratosis, increase in viable epidermis and dermal thickness)
39
AHA is used in rhytides
True (increased production of collagen and intercellular ground substances, causing reversal of the epidermal and dermal markers of photoaging)
40
AHA is used in dermatoheliosis
True (increased production of collagen and intercellular ground substances, causing reversal of the epidermal and dermal markers of photoaging)
41
AHA is used to reverse the changes seen in brittle aged nails
True
42
AHA is used in acne vulgaris because of its unique effect of superficial and controlled desquamation on the stratum corneum
True (5-10% once to twice daily as a home regimen, 35-70% for short exposures in the office setting as a superficial chemical peel)
43
AHA is used in Rosacea
True
44
AHA (specifically Glycolic acid and lactic acid) is effective in hyperpigmentation and pigmented lesions such as solar lentigines, melasma
True (decreased melanin in the epidermis on histology may be related to epidermal remodelling and turnover, as well as tyrosinase activity)
45
AHA is used in actinic keratosis as a pre-treatment regimen prior to topical 5-FU cream as this resulted in shorter healing time than 5-FU monotherapy and equivalent efficacy in the reduction of AKs
True (20% Glycolic acid peels once weekly for 4 weeks > topical 5-FU cream daily for 4 weeks)
46
It was once thought that thinning of the stratum corneum in normal skin might increase water loss and cause skin sensitivity to potentially irritating chemicals, however treatment with low concentration Glycolic acid does not affect the organisation of barrier lipids in the stratum corneum or increase transepidermal water loss
True
47
Surprisingly, prolonged use of some AHA formulations actually make stratum corneum more resistant to potentially irritating substances such as detergents
True
48
Compared to AHA, preliminary studies of PHA have been shown to have equivalent anti-aging effects
True
49
Both AHA and PHA are well tolerated, but patients report associated burning and stinging with AHA products
True
50
Glycolic acid peels can be used for dermatoheliosis by starting at a low % Glycolic acid and then gradually increasing this on an individual basis as tolerated
True
51
Patients with oily skin are less reactive to Glycolic acid peels
True
52
Patients with excessive sun-induced or environmental damage are more sensitive to Glycolic acid peels
True
53
Patients are encouraged to repeat a previous treatment regimen (% AHA and duration) if they experienced excessive irritation of peeling with the last treatment
True
54
Some authors believe that patients who used a combination therapy of Tretinoin (retinoid) and Glycolic acid (AHA) have better acne control than with either agent alone
True (Glycolic acid aids in comedone extrusion whilst Tretinoin prevents new comedone formation) - therefore some dermatologists prescribe a Tretinoin at night and an appropriate AHA for the morning
55
Monthly superficial AHA (Glycolic acid) peels are usually added to the management of acne as Glycolic acid helps to resolve non-inflammatory, superficial inflammatory and nodulocystic acne lesions
True
56
When using AHA peels in conjunction with Tretinoin for acne, physicians must be aware that Tretinoin increases the depth of treatment and the resultant exfoliation
True (use a more superficial peel instead)
57
AHA (Glycolic acid 8% lotion) is also reported to be effective in treating pseudofolliculitis barbae, resulting in reduction of lesions with little irritation
True
58
AHA (Glycolic acid) peels reduce the inflammation in Rosacea
True
59
Although topical retinoids have been used for Rosacea, they can produce excessive irritation and exacerbate the telengiectatic component, which is in contrast to AHA which do not promote angiogenesis
True
60
AHA may prevent attachment of the Demodex mite in the follicles of Rosacea patients through the AHA effect on corneocyte adhesion
True
61
The low pH of AHA (Glycolic acids) may deplete bacterial nutrients and reduce the presence of viable pathogens in Rosacea patients
True
62
For patients with papulopustular Rosacea, AHA (Glycolic acid) peels may be used on a daily basis and in the office setting similar to that described for acne vulgaris
True
63
Glycolic acid (AHA) may be used in combination with other bleaching agents such as hydroquinone to enhance each other's penetrance and yielding a better therapeutic response for management of pigmentary disorders
True
64
Glycolic acid (AHA) may be combined with 'Kligman regimen' (hydroquinone, Tretinoin, topical corticosteroid) for greater skin lightening effects in pigmentary disorders
True
65
AHA (Glycolic acid) peels are effective and safe in medium to dark skinned individuals but the % Glycolic acid and the peeling time must be increased with caution due to the risks of more chemical irritancy and possible post-inflammatory hyperpigmentation
True
66
Chemical peeling agents used in the office setting contain AHA concentrations from 20-70%
True
67
The topical efficacy of an AHA formulation depends on its bioavailability concentration and the vehicle used
True
68
For topical treatments, penetration of the stratum corneum is the major limiting factor determining the free AHA concentration in the epidermis and dermis
True
69
For AHA formulations, the closer the pH is to neutral (pH7), the less the irritation there is to the skin
True (AHA can be neutralised with an inorganic alkali or organic base to raise the pH, making the formulation less irritating to the skin)
70
The AHA can also be buffered to create a compound that resists pH changes when an acid or alkali is added in order to maintain a range of pH i.e between 2.8 and 4.8, although this reduces the free acid levels and efficacy of the AHA preparation
True (buffering is not synonymous to neutralisation of an AHA formulation)
71
The bioavailability of AHA (free acid levels) can be calculated from both the pH of the preparation and the concentration of the AHA
True
72
Because glycolic acid is water soluble, most Glycolic acid in the water phase is in direct contact with stratum corneum when applied topically
True (hence vehicle plays a role in absorption)
73
Glycerin (used in vehicles) has a strong affinity for AHA and because Glycerin cannot substantially penetrate the stratum corneum, it reduces the AHA absorption
True
74
Propylene glycol in the vehicle can enhance the penetration of AHA by modifying the permeability of the stratum corneum
True
75
When selecting a topical therapy with AHA, the physician should choose a vehicle that enhances drug delivery, is non-irritating and promotes patients compliance
True
76
There is clearly an inverse relationship between the pH of AHA preparations and their potential for skin irritation
True (higher the pH, lower potential for skin irritation)
77
Skin irritation depends on the pH of the AHA formulation and not the AHA %, as the pH of the AHA formulation is lowered, the potential for skin irritation is increased
True (there is an inverse relationship between pH of AHA and their potential for skin irritation)
78
As the pH of AHA formulation is nearer to neutrality at 4.4, the cutaneous irritation dropped off markedly
True
79
The epidermal effects such as thinning of the stratum corneum and thickening of the viable epidermis is noted when patients are treated with a Glycolic acid product with pH 3.8 but the efficacy of Glycolic acid diminishes when the pH approaches 4.4
True
80
The ideal pH for an AHA formulation is 3.8
True (lower % AHA also produces significant dermal effects at pH 3.8 + efficacy of Glycolic acid on epidermal effects diminishes the pH approaches 4.4)
81
More rapid absorption and subsequent irritation from AHA occurred at lower pH levels
True
82
AHA may cause burning
True
83
AHA may cause dermatitis
True
84
AHA may cause swelling
True
85
AHA may cause skin discolouration
True
86
AHA may cause blistering
True
87
AHA may cause peeling
True
88
AHA may cause itching
True
89
The most common adverse effect from AHA use is irritant contact dermatitis
True
90
Irritant contact dermatitis from AHA can be managed by reducing the AHA concentration, altering the application schedule or increasing the pH of the product
True
91
Most patients experience mild erythema, burning, stinging for several minutes to a few hours after a superficial AHA peel
True
92
If the reaction from a superficial AHA peel is more severe or prolonged such as scaling, crusting, or blistering; application of a topical corticosteroid can be helpful
True
93
Pigmentary disturbances may result from a AHA chemical peel and necessitate additional treatment
True
94
All skin types are susceptible to hypopigmentation following a deep AHA chemical peel but this is rare
True
95
Hyperpigmentary problems from AHA peels are more often encountered in dark skinned individuals and usually respond to treatment with Tretinoin and/or bleaching creams
True (proper photoprotection is recommended for several weeks following a peel)
96
Larger molecular weight AHA (Malic acid, citric acid) tend to remain on the skin surface much longer, therefore producing more of an epidermal effect as the stratum corneum resists penetration of these compounds
True (these larger molecular weight AHA also result in less stinging and burning than the lower molecular weight AHA)
97
HSV infection can rarely be triggered from a AHA peel due to chemical and/or inflammatory trauma, therefore prophylactic acyclovir, Valacyclovir or Famciclovir can be used to minimise postoperative herpetic infections in patients who are prone to such outbreaks
True
98
Short term topical application of Glycolic acid increases the skin's photosensitivity
True (Unknown mechanism, advisable for patients to wear adequate sunscreen when using AHA)
99
One possible explanation for AHA-induced photosensitivity is that UVR is transmitted through normally moisturised skin than through dry skin as dry skin scatters or reflects UVR
True (AHA reduces stratum corneum thickness/hyperkeratosis and remodels the epidermis)
100
The tumour prevention effects of AHA may be attributed to the removal of photodamaged keratinocytes
True
