3 - Agents used for Hyperkeratosis

Question 1

The following are agents used for the treatment of hyperkeratosis:

(1) salicylic acid (BHA or a phenolic aromatic acid)
(2) sulfur
(3) tar
(4) urea
(5) lactic acid (AHA)
(6) glycolic acid (AHA)

Answer 1

True

Question 2

Salicylic acid and salicylates (which are easily converted to salicylic acid) are present in willow bark, wintergreen leaves and sweet birch

Answer 2

True

Question 3

Salicylic acid has been classified as either a beta-hydroxy acid (BHA) or more accurately as a phenolic aromatic acid

Answer 3

True (unlike a true BHA, salicylic acid has both the hydroxyl and carboxyl groups directly attached to an aromatic benzene ring and the hydroxyl group exhibits acid properties; whereas the hydroxyl group of a true BHA is neutral)

Question 4

Salicylic acid is lipid soluble and therefore miscible with epidermal lipids

Answer 4

True (in contrast to AHA such as Glycolic acid and lactic acid which are water soluble)

Question 5

Salicylic acid is lipid soluble and therefore miscible with sebaceous glands lipids in hair follicles

Answer 5

True (in contrast to AHA such as Glycolic acid and lactic acid which are water soluble)

Question 6

Salicylic acid is lipid soluble and therefore can interact with lipids that surround keratinised cells

Answer 6

True (in contrast to AHA such as Glycolic acid and lactic acid which are water soluble)

Question 7

Salicylic acid is lipid soluble and therefore is able to interact with multilamellar structures surrounding keratinocytes in the stratum corneum and in hair follicles

Answer 7

True (in contrast to AHA such as Glycolic acid and lactic acid which are water soluble)

Question 8

Because of the greater lipophilic qualities of salicylic acid in contrast to the water solubility of AHA, the clinical effect of salicylic acid may be limited to the superficial epidermis

Answer 8

True (AHA free acids may penetrate deeper into the epidermis and dermis as well)

Question 9

Salicylic acid has a pKa (acid dissociation constant) of 2.98 and must be formulated at a proper pH to allow enough free acid to be present to obtain a significant exfoliative effect

Answer 9

True (various formulations with concentrations of salicylic acid at a pH close to pKa give significantly more exfoliation than formulation at any pH significantly greater than the pKa)

Question 10

Salicylic acid formulations with concentrations of at a pH close to its pKa (acid dissociation constant) give significantly more exfoliation than formulation at any pH significantly greater than the pKa

Answer 10

True (salicylic acid pKa = 2.98)

Question 11

Salicylic acid has keratolytic and desmolytic effects

Answer 11

True (desmolytic more accurately describes the mechanism of action)

Question 12

Salicylic acid and its derivatives have sunscreen effects (such as the UVB absorber octisalate/octyl salicylate)

Answer 12

True (therefore topical Salicylic acid which is frequently used in psoriasis can interfere with UVB phototherapy for psoriasis)

Question 13

Salicylates such as acetylsalicylate (aspirin) and Salicylic acid have anti-inflammatory properties

Answer 13

True (the anti-inflammatory effect of a Salicylic acid is most pronounced at 0.5% and 5%)

Question 14

Salicylic acid exerts its keratolytic and desmolytic effects by:

(1) reducing corneocyte adhesion
(2) loosening and causing detachment of corneocytes

Answer 14

True

Question 15

The term ‘desmolytic’ is more preferable to ‘keratolytic’ in regard to the mechanism of action of salicylic acid as Salicylic acid disrupts the cellular junctions (desmosomes) rather than lysing/breaking intercellular keratin filaments

Answer 15

True (acts as an organic solvent to remove the intercellular lipid linking the cornified cells)

Question 16

Salicylic acid causes a more irregular and thinner stratum corneum without altering the epidermal thickness

Answer 16

True (in contrast the AHA that thins the stratum corneum, but increases thickness of the viable epidermis and dermis)

Question 17

Salicylic acid is used for the following hyperkeratotic disorders:

(1) calluses
(2) corns
(3) hyperkeratosis
(4) ichthyosis
(5) keratoderma

Answer 17

True
Calluses/corn = 2-20% Salicylic acid in collodion-based paint and gels, 10-50% Salicylic acid in a plaster
Hyperkeratosis = 6% Salicylic acid multi vesicular emulsion cream
Ichthyosis/keratoderma = 6% Salicylic acid + 60% propylene glycol + 20% ethanol

Question 18

Salicylic acid is used for the following cosmetic indications:

(1) hyperpigmentation
(2) rejuvenation/peeling

Answer 18

True

Question 19

Salicylic acid is used for the following papulosquamous dermatosis:
(1) psoriasis

Answer 19

True

Question 20

Salicylic acid is used for the following cutaneous infections:

(1) dermatophyte infections
(2) verruca (HPV)

Answer 20

True
Dermatophyte = 6% Salicylic acid + 12% benzoic acid in wool fat and petrolatum (Whitfield’s ointment), 10% Salicylic acid + 20% urea for avulsing toenails
Verruca = 2-20% Salicylic acid in collodion-based paint and gels, 10-50% Salicylic acid in a plaster

Question 21

Salicylic acid is used for the following dermatitis:

(1) cradle cap
(2) seborrhoeic dermatitis

Answer 21

True

Shampoos with 2% Salicylic acid, often in combination with tar and Sulfur

Question 22

Salicylic acid may be used in acne vulgaris due to its mild comedolytic effects

Answer 22

True

Question 23

In the treatment of psoriasis, Salicylic acid is added into topical preparations containing dithranol to prevent its oxidation

Answer 23

True

Question 24

In the treatment of psoriasis, the original Lassar’s paste contained 2% Salicylic acid + 24% zinc oxide + 24% starch + 50% WSP

Answer 24

True (although compounds duplicating the original Lassar’s paste should always be freshly prepared because the ingredients combine to form zinc salicylate on standing) - modern formulations of Lassar’s paste do not contain Salicylic acid because of the interaction of salicylic acid and zinc oxide

Question 25

In treatment of psoriasis, compounding calcipotriene with Salicylic acid should be avoided as this results in instability of calcipotriene when mixed with Salicylic acid

Answer 25

True

Question 26

Salicylic acid has been used for pruritus

Answer 26

True (antipruritic formulations at a concentration of 1-2%)

Question 27

Salicylic acid has been used for painful aphthous ulcers and for topical musculoskeletal symptomatic pain relief

Answer 27

True Aphthous ulcers = choline salicylate MSK pain = methyl salicylate found in oil of wintergreen

Question 28

Salicylic has been used as a superficial peeling agent as part of Jessner's solution which consists of 14% Salicylic acid + 14% resorcinol + 14% lactic acid in ethanol

Answer 28

True

Question 29

Salicylic acid in concentrations of 20-30% in a hydroethanolic vehicle is also used as a superficial chemical peel for acne, photodamage, and hyperpigmentation

Answer 29

True

Question 30

The effect of salicylic acid in chemical peeling procedures is largely related to epidermal injury

Answer 30

True

Question 31

50% Salicylic acid ointment has been used to treat severely photodamaged hands and forearms

Answer 31

True

Question 32

1-2% Salicylic acid is used as an exfoliant to increase corneocyte shedding and improve the appearance of aged skin

Answer 32

True

Question 33

Salicylic acid has been used in hyperhidrosis

Answer 33

True (2% Salicylic acid to 15% aluminium chloride hexahydrate is efficacious and less irritating than preparations that contained aluminium chloride hexahydrate only)

Question 34

When applied topically to the skin, Salicylic acid is readily absorbed

Answer 34

True (risk of systemic absorption and salicylism)

Question 35

Percutaneous absorption of salicylic acid is enhanced by incorporation into hydrophilic ointment

Answer 35

True (risk of systemic absorption and salicylism)

Question 36

If Salicylic acid is applied to erythrodermic skin, it can be detected in the urine within 24 hours

Answer 36

True (risk of systemic absorption and salicylism)

Question 37

Percutaneous absorption of salicylic acid is enhanced by tape stripping of the stratum corneum

Answer 37

True (risk of systemic absorption and salicylism)

Question 38

Percutaneous absorption of salicylic acid is enhanced by application under occlusion

Answer 38

True (risk of systemic absorption and salicylism)

Question 39

Systemic toxicity due to percutaneous absorption of salicylic acid is rare, but a potentially serious event as salicylates in high concentrations are toxic to the CNS

Answer 39

True

Question 40

Salicylates in high concentrations causes CNS toxicity including nausea, vomiting, tinnitus, confusion, dizziness, delirium, psychosis, stupor, coma and death

Answer 40

True

Question 41

Tinnitus due to salicylate toxicity is caused by increased labyrinthine pressure and effects on cochlear hair cells secondary to vasoconstriction in the auditory microvasculature

Answer 41

True

Question 42

Salicylate toxicity stimulates the medullary respiratory centre in the brain that causes marked hyperventilation and respiratory alkalosis, and in infants and children metabolic acidosis may occur

Answer 42

True

Question 43

Signs of salicylate toxicity generally occur when blood concentrations exceed 35 mg/dL

Answer 43

True

Question 44

Salicylate systemic toxicity causes the following GI effects: (1) nausea (2) vomiting

Answer 44

True

Question 45

Salicylate systemic toxicity causes the following neurological effects: (1) confusion (2) dizziness (3) delirium (4) psychosis (5) stupor (6) coma (7) death

Answer 45

True

Question 46

Salicylate systemic toxicity causes the following metabolic effects: (1) respiratory alkalosis (2) metabolic acidosis in infants and children (3) hypoglycaemia

Answer 46

True

Question 47

Tinnitus is an early warning sign of salicylate systemic toxicity

Answer 47

True

Question 48

Salicylate systemic toxicity causes hyperventilation

Answer 48

True (stimulation of medullary respiratory centre in the brain)

Question 49

Symptoms of Salicylate toxicity appeared early in the course of treatment, frequently within 2-3 days of initiating therapy

Answer 49

True

Question 50

Salicylates affect glucose utilisation and may lead to hypoglycaemia, especially in patients with uraemia due to reduced protein binding of salicylates

Answer 50

True

Question 51

Salicylic acid is only a weak contact sensitiser, and the incidence is rare

Answer 51

True

Question 52

Sulfur has antiparasitic properties

Answer 52

True (used for scabies in topical formulations)

Question 53

Sulfur has anti-acne properties

Answer 53

True (used for acne, Rosacea and perioral dermatitis)

Question 54

Sulfur has anti-seborrhoeic properties

Answer 54

True (used for seborrhoeic dermatitis and pityriasis versicolor)

Question 55

Sulfur is a yellow non-metallic element

Answer 55

True

Question 56

The 2 Sulfur preparations used in dermatology include: | 1) sublimed Sulfur (2) precipitated Sulfur (smaller particle size allowing for greater interaction with skin

Answer 56

True sublimed Sulfur = produced by direct conversion of crude Sulfur from solid phase to gas precipitated Sulfur = produced by boiling sublimed Sulfur with lime and water and then adding hydrochloric acid resulting in very fine particles

Question 57

Precipitated Sulfur is the most common Sulfur used in dermatology

Answer 57

True (sublimed Sulfur is also used, but not as common) - precipitated Sulfur has smaller particle size and has greater interaction with skin

Question 58

Sulfur has keratolytic effects (breaking down of the stratum corneum) at high concentrations and although the exact mechanism is unknown, the interaction of Sulfur with cysteine in keratinocytes that leads to release of hydrogen sulfide probably accounts for the break down of keratin and cause dissolution of the stratum corneum

Answer 58

True (lower concentration Sulfur produces keratoplastic effects)

Question 59

Sulfur has antifungal effects which relates to the formation of pentathionic acid by cutaneous bacteria and keratinocytes, as well as the keratolytic effects of Sulfur which causes shedding of infected stratum corneum

Answer 59

True

Question 60

Sulfur has antiseptic properties

Answer 60

True

Question 61

Sulfur has antibacterial effects as it demonstrates inhibitory effect on the growth of P. Acnes, some streptococci and staph aureus

Answer 61

True

Question 62

Sulfur has keratoplastic effects (normalisation of keratinisation and epidermal cell maturation) at low concentrations, which also relates to the interaction between Sulfur and cysteine that promotes normal keratinisation

Answer 62

True (higher concentrations of Sulfur has keratolytic effects)

Question 63

The use of Sulfur in the treatment of Rosacea may be due to killing of Demodex mites implicated as a causative factor in some cases of Rosacea (antiparasitic effects)

Answer 63

True

Question 64

The action of Sulfur in scabies is poorly understood although the formation of hydrogen sulfide (from the interaction of Sulfur and cysteine) and polythionic acid which are toxic to the mite, and the shedding/keratolytic effects of the stratum corneum through which the mites burrows may be the mechanism of action in the treatment of scabies

Answer 64

True (Sulfur was used before the availability of permethrin, but there are no well designed studies regarding the efficacy and toxicity of Sulfur in the therapy of scabies)

Question 65

Sulfur penetrates the skin within 2-8 hours of topical application

Answer 65

True

Question 66

The anti-acne properties of Sulfur may not be related to its keratolytic effect, but may instead be related to non-specific irritant effects that lead to peeling (desquamative effects)

Answer 66

True

Question 67

Fatal toxicity after Sulfur was applied to large areas of the skin of infants has been reported rarely

Answer 67

True

Question 68

Sulfur may cause allergic contact dermatitis

Answer 68

True

Question 69

Tar has antiproliferative effects on the epidermis and appears to exert its actions through suppression of DNA synthesis consequently leading to reduction of mitotic activity in the basal layer of the epidermis

Answer 69

True

Question 70

In combination with UV light, tar reduced epidermal proliferation more effectively than with either treatment modality alone

Answer 70

True (the combination of tar and UV therapy for psoriasis is called 'Goeckerman regimen')

Question 71

Tar (specifically bituminous marine fossil-derived tar) has anti-inflammatory activity caused by inhibition of chemotaxis of neutrophils due to leukotrienes

Answer 71

True

Question 72

Tar preparations are useful topical therapy for inflammatory skin diseases such as psoriasis, atypical dermatitis, seborrhoeic dermatitis

Answer 72

True (can also be used in eczematous dermatitides, pityriasis versicolor and dermatophyte infections as tar has antifungal properties against yeast, dermatophytes and hypomycetes; vitiligo, pruritus)

Question 73

Tar shampoos are commonly used to treat seborrhoeic dermatitis of the scalp

Answer 73

True (shale oils also have antifungal properties against yeast, dermatophytes and hypomycetes)

Question 74

Tar has been associated with possible skin carcinogenesis but has been declared effective and safe as clinical studies in numerous patients demonstrated that the skin cancer incidence in these patients is no different from that of the general population

Answer 74

True (the skin cancer incidence is increased in patients with psoriasis who received extensive treatment with tar and UVR but the relative contributions of the UVR and the tar components to this carcinogenesis is unknown)

Question 75

Scrotal SCC in association with tar exposure is a well-known occupationally induced cancer

Answer 75

True (although the use of protective clothing, better hygiene and less scrotal exposure to carcinogens made tar-induced scrotal SCC primarily of historical significance only)

Question 76

The cancer potential of tar has been linked to its carcinogen content

Answer 76

True (major carcinogenic agents in tar are polyaromatic hydrocarbons such as benzapyrene, anthracene and pyridines)

Question 77

Tar preparation of dermatologic importance are derived from 3 main organic sources: (1) bituminous coal (crude coal tar) (2) wood (wood tar) (3) marine fossils (bituminous tar/sulfonated shale oil)

Answer 77

True

Question 78

Crude coal tar derived from bituminous coal is the most widely used form of tar in dermatology and contains polyaromatic hydrocarbons (and the major carcinogenic agents benzapyrene, anthracene, pyridines), phenols and nitrogen bases

Answer 78

True

Question 79

Wood tar derived from wood is also rich in polyaromatic hydrocarbons (just like crude coal tar), but have fewer carcinogenic agents (such as anthracene and pyridines) than crude coal tar; although is more irritating and toxic due to the higher phenol absorption properties

Answer 79

True

Question 80

Bituminous tar/sulfonated shale oil derived from marine fossils has comparatively low levels of polyaromatic hydrocarbons carcinogenic agents (benzapyrene, anthracene, pyridines) than crude coal tar and wood tar

Answer 80

True

Question 81

A major disadvantage of the use of tar is poor compliance due to the smell, appearance, and staining capacity

Answer 81

True (as a consequence crude coal tar has been modified to produce LPC)

Question 82

Liquor picis carbonis (LPC) is an alcohol extract of crude coal tar that is more cosmetically acceptable, but is therapeutically inferior to crude coal tar

Answer 82

True (although patient acceptance of LPC exceeds that of other forms of tar)

Question 83

Crude coal tar causes photosensitivity and is an adverse effect that is responsible (in part) for the therapeutic effect of the Goeckerman regimen

Answer 83

True (wood tar and bituminous tar/sulfonated shale oil do not photosensitise and are more cosmetically attractive than crude coal tar) Goeckerman regimen = tar + UV therapy

Question 84

In contrast to crude coal tar, wood tar and bituminous tar/sulfonated shale oil do not photosensitise and are more cosmetically attractive than crude coal tar

Answer 84

True

Question 85

Tar smarts is the phototoxicity from natural sunlight and inadvertent tar exposure, due to the UVR wavelengths in the UVA spectrum (320-400 nm)

Answer 85

True

Question 86

Phototoxic and photoallergic reactions to tar products have been reported

Answer 86

True

Question 87

More often allergic contact dermatitis appears to occur with wood tar and may cross-react with colophony, balsam of Peru, and turpentine

Answer 87

True

Question 88

The phototoxic dermatitis from coal tar products can result in poikiloderma

Answer 88

True

Question 89

The acute toxic potential of tar (mainly wood tar due to its high phenol content) is due to phenol

Answer 89

True (newer products have been manufactured with reduced phenol content to minimise the risk for phenol toxicity)

Question 90

Tar products may cause irritant reactions as well

Answer 90

True

Question 91

Tar can cause pruritus

Answer 91

True

Question 92

Tar can cause folliculitis

Answer 92

True

Question 93

Tar can cause comedones

Answer 93

True

Question 94

Tar can cause acneiform eruptions

Answer 94

True

Question 95

Tar can cause keratoses (tar warts)

Answer 95

True

Question 96

Tar can cause keratoacanthomas

Answer 96

True

Question 97

Urea has antimicrobial properties

Answer 97

True (inhibit the growth of some microorganisms)

Question 98

Urea has humectant (moisturising properties that reduce transepidermal water loss and increase skin hydration) properties by absorbing water from the atmosphere in high humidity environment due to its high water solubility and low water vapour pressure

Answer 98

True (enhancer of protein-water binding capacity)

Question 99

Urea has keratolytic properties by: (1) incorporating itself into the stratum corneum and breaking hydrogen bonds to reach the interior of epidermal keratins (2) water solubility and water-binding capacity giving it the humectant characteristics leading to increased desquamation of corneocytes

Answer 99

True (high concentrations of urea is a protein solvent and denaturant and has the ability to macerate dystrophic nails due to its hydrating properties)

Question 100

Urea is bipolar, rendering the molecule water soluble and capable of ionic interactions with salt solutions leading to an increase in water-binding capacity when mixed with sodium chloride

Answer 100

True

Question 101

As urea is the end product of the catabolism of animal proteins, urea is not an energy source for most pathogenic bacteria and therefore does not promote pathogenic bacterial growth

Answer 101

True

Question 102

Urea enhances the percutaneous absorption of various chemicals and pharmaceutical agents

Answer 102

True

Question 103

Urea 10-25% has humectant, antipruritic and mild keratolytic properties and is used for: (1) Xerosis (2) hyperkeratosis (3) atopic dermatitis (4) xerotic dermatitis (5) keratosis pilaris (6) keratodermas (7) icthyosis

Answer 103

True

Question 104

Urea 40-50% has humectant and keratolytic properties and is used for: (1) calluses (2) chemical avulsion of dystrophic nails (3) hyperkeratosis

Answer 104

True

Question 105

Topical urea preparations can cause irritant reactions (related to the high acidity of the preparations) and maceration (owing to the humectant properties), but are these more likely with the higher concentration products and especially if used under occlusion

Answer 105

True

Question 106

Application of urea in excoriated or fissured skin can produce stinging and irritation and is related to the high acidity of the preparations (usually pH 3 or less)

Answer 106

True (new stabilised preparations claim less acidity and consequently less irritation)