Pharmacology for Dentistry

452 Section 13/ Miscellaneous

people as a result of the increased level of
melanin pigment in the skin. If the affected
area only extends into the skin epidermis,
this makes it easier to treat because the af-
fliction only involves the superficial layers
of the skin. Therefore, patients will respond
faster to treatment. However, if the condi-
tion affects deep layers of the skin, such as
dermis, treatment may need to be prolonged
or may require other alternatives.

Hydroquinone and monobenzone are
used to reduce hyperpigmentation of the
skin. Trioxsalen and methoxsalen used for
repigmentation of depigmented macules of
vitiligo.

Azelaic acid is a newer treatment for
hyperpigmentation, primarily for post-
inflammatory hyperpigmentation. It works
by blocking the activity of tyrosinase and
does not cause photosensitivity of the skin
or residual changes in the skin. There is
decreased incidence of allergic reactions
associated with azelaic acid. Corticosteroids
also block the activity of tyrosinase.
Corticosteroids are used in combination
with other drugs to minimize the side
effects. The combination of azelaic acid and
hydrocortisone acetate (10%) may also be
useful in the treatment of post-inflammatory
hyperpigmentation of skin

SUNSCREENS

These are the agents which protect the skin
from harmful effects of exposure to sunlight
by absorbing ultraviolet light. The most com-
monly used compounds are paraamino ben-
zoic acid (PABA) and its esters and ben-
zophenones include oxybenzone,
dioxybenzone and sulisobenzone. These

benzophenones provide a broader spectrum

of absorption from 250 to 360 nm.

Various physical sunscreens such as

heavy petroleum jelly, zinc oxide, titanium

oxide, calamine are also used, which can

stop and scatter ultraviolet rays

ACNE PREPARATIONS

Acne is a common skin condition, which

consists of blackheads, white heads, and

sometimes deeper boil-like lesions called

nodules or cysts. It occurs during the teen-

age years in boys and girls.

Acne vulgaris affects the pilosebaceous

units to the skin, leading to their eventual

blockade and development of acne lesions.

Abnormal desquamation, defective

keratinisation, blockade of the follicular ori-

fice and collection and colonization of sebum

lead to proliferation of Propionibacterium acnes.

RETINOIC ACID

Retinoic acid is an effective treatment of

acne vulgaris and is used topically. It

stabilizes lysosomes, increases ribonucleic

acid polymerase activity, increases

prostaglandin E 2 , cAMP and cGMP level.

Adapalene is a napthoic acid derivative

with retinoid-like activity used for the

topical treatment of acne vulgaris. Adverse

effects include erythema, dryness of skin

and skin irritation.

Isotretinoin is a synthetic retinoid which

acts by inhibiting sebaceous gland size and

function.

Azelaic acid is also used in the treatment

of acne.