Transcript 8th Lecture 1434 - Home - KSU Faculty Member websites

Pharmacology-4 PHL 425
Eighth Lecture
By
Abdelkader Ashour, Ph.D.
Phone: 4677212
Email: [email protected]
Anti-Warts Drugs
Anti-Warts Drugs, Introduction
 Cutaneous warts are benign epidermal proliferations caused by human
papillomavirus (HPV) infection
 Papillomaviruses (small DNA viruss) comprise a family of viruses that are hostspecies specific. Thus, HPV causes disease only in humans, infecting epithelial
tissues and mucous membranes
 Cutaneous warts are one of the most common skin conditions affecting
children
 Transmission of warts occurs from direct person-to-person contact or
indirectly by fomites
 Swimming pools and bathrooms are common areas for the spread of warts if
the skin is macerated and touches rough surfaces
 Once HPV has infected the skin, autoinoculation can occur by scratching,
shaving or traumatizing the skin
 Previously infected patients have a higher risk for development of new warts
than those never infected
Anti-Warts Drugs, Introduction
 Types of warts; genital or non genital (venereal or nonvenereal)
 Nongenital warts occur in 7% to 10% of the general
population, with the incidence peaking between the ages
of 12 and 16 years
 Warts occur equally in both sexes and are among the
three most common dermatoses treated
 Owing to natural immunity, approximately 23% of warts
regress spontaneously within 2 months, 30% within 3
months and 65% to 78% within 2 years
 The rate of clearance is influenced by factors such as viral
type, host immune status, extent and duration of warts
Anti-Warts Drugs, Introduction
 The clinical picture of cutaneous warts differs
by specific location on the body:
Verruca vulgaris (common warts) are
hyperkeratotic, exophytic and domeshaped papules or nodules especially
located on fingers, hands, knees, elbows or
any other sites of trauma. Generally, they
are asymptomatic but sometimes cause
mild pain
Plane or flat warts are smooth flat topped
papules with minimal scaling and only slight
elevation, most often on the face. They are
more common in children and young adults.
They generally cause no symptoms but can
be difficult to treat
Anti-Warts Drugs, Introduction
Plantar warts are warts on the sole
of the foot
 They can be painful due to their
callused, endophytic papules
that have deeply penetrating
sloping sides and a central
depression
Numerous coalesced warts on the
plantar surface will form a tile-like
pattern known as mosaic warts. As
with other plantar warts, they are
often tender
Anti-Warts Drugs, Introduction
 Filiform warts are long, frondlike
growths usually on the eyelids,
face, neck, or lips. They are
usually asymptomatic. This
morphologically distinct variant of
the common wart is benign and
easy to treat
 Periungual warts appear as
thickened, fissured cauliflower-like
skin around the nail plate. Patients
frequently lose the cuticle, and are
susceptible to paronychia. These
warts are more common in patients
who bite their nails
Genital warts
 The most common sexually transmitted disease worldwide
 Most people do not know they have it (generally asymptomatic)
 Anogenital warts occur in the perineum and on the genitalia
or in the genital tract

Some types are considered “low risk” , other types are
considered “high risk” and can cause pre-cancerous lesions
and can lead to cancer of the cervix, anus and other genital
areas

> 90% of anogenital warts resolve within 2 years, however,
persistent infection with high-risk HPV subtypes is the main
cause of cervical and anal cancer

Parts of the viral DNA link to specific genes in human cells,
transforming them into cancer cells
Treatment of Warts, Intro
 The American Academy of Dermatology developed criteria for the indications for
wart treatment including:
1)
2)
3)
4)
5)
6)

the patient’s desire for therapy
symptoms of pain, bleeding, itching or burning
disabling or disfiguring lesions
large numbers or large sizes of lesions
the patient’s desire to prevent the spread of warts to unblemished skin of self or others
an immunocompromised condition
Anogenital warts should receive special consideration and warrant vigilance for other
sexually transmitted diseases
 Extragenital warts in people who are immunocompetant are harmless and usually
resolve spontaneously within months or years owing to natural immunity
 In view of this, a policy of not treating them is often advised. However there is
considerable social issues associated with warts on the face and hands, and they
can be painful on the soles of the feet and near the nails. Therefore, many patients
request treatment for their warts
Treatment of Warts, Overview
The goal of wart treatment is to destroy or remove
the wart without creating scar tissue, which can be
more painful than the wart itself
 Start with the least painful, least expensive and
least time-consuming methods
 Reserve the more expensive and invasive
procedures for refractory warts
 Home treatment is often effective in curing
common warts (salicylic acid)
Treatment of Warts
A) Destructive measures:
1. Physical
2. Chemical
B) Immuno-modulatory measures
1- Physical methods
• Electrocautery: use of electric current to burn off
the warts
• Cryocautery: use of liquid nitrogen to freeze off
the warts
• Laser: a laser beam or intense lights to destroy
the warts
• Surgical excision is usually reserved for warts
that haven't responded to other therapies
(scarring)
Freezing (cryotherapy or liquid nitrogen
therapy)
 Cryotherapy is used to deep freeze the wart
tissue
 When liquid nitrogen is applied to the wart, the
water in the cells expands, thus exploding the
infected tissue
 The exploded cells can no longer hide the
human papillomavirus from the body's immune
system
 The immune system then works to destroy the
virus particles
 Best for pregnant women
Laser Therapy
• Lasers are simply very intense light
sources
• This light has an enormous amount of
energy that heats the tissue enough that it
vaporizes
• Pulse dye laser or carbon dioxide (CO2)
laser
2. Chemicals
They must be applied by a trained health care
provider to destroy warts
 Trichloroacetic acid and glacial acetic acid
 These are caustic compounds that cause tissue necrosis
 Podophyllin is a cytotoxic compound (best for genital
warts)
 Podophyllotoxin is a purified ingredient of podophyllin
 In addition, home treatment is available and effective in
curing common warts (salicylic acid)
Treatment of Warts, Home treatment
 Salicylic acid (SA) is a first-line therapy for warts
 It is a keratolytic (i.e., dissolves the keratin which makes up most of the wart and the
thick layer of dead skin that tops it) therapy with a mechanism of action that slowly
destroys virus-infected epidermis and may cause an immune response from the mild
irritation caused by the salicylic acid
 It is prepared in concentrations from 10% to 70%.
 Over-the-counter preparations are available as 17% SA combined in a base of
flexible collodion (as a liquid to paint on the wart) or as a 40% salicylic acid plaster
patch, to be cut out and placed on the wart tissue
 The advantages of over-the-counter SA include convenience, minimal expense,
negligible pain and reasonable effectiveness
 Disadvantages are that results require weeks to months of treatment, and the
patient must strictly adhere to instructions
 Side effects can include occasional contact dermatitis due to colophony in the
collodion base. There is also a potential risk of systemic toxicity in children that can
be avoided if lower concentrations or limited areas of treatment are used
 Plantar warts may be more amenable to treatment with SA with occlusion than hand
warts
 Wart paints should not be used to treat facial warts because of severe irritation and
a potential for scarring
Home treatment is effective in curing
common warts (salicylic acid)
 SA is available for application to all kinds of warts, from tiny ones to great,
big lumpy ones
 The wart area should be soaked in warm water for 5-10 minutes
 The wart should then be pared down with a razor
 Care should be taken to not make the wart bleeds
 The SA preparation is then applied to the wart tissue only
 This could be repeated 3 times a week until full recovery
B) Immune response modifiers
 Local immune enhancers that stimulate
production of interferons or cytokines
 Interferon -alfa is a naturally occurring cytokine
with antiviral and immunomodulatory effects. It can
be injected directly into warts
 Imiquimod: a topical cream or gel that is used for
genital warts. It helps the body's immune system
fight the wart virus through stimulation of T-helper
cells
Antiviral Agents
 Cidofovir is active against all DNA viruses
 Topical cidofovir 1% gel can be applied to the
lesions at bedtime and left on overnight, three
times a week for up to 16 weeks
 Because cidofovir possesses direct antiviral
effects, topical cidofovir does not require a
competent immune system to be effective and
therefore has a greater benefit in patients with
HIV infection
Other therapies
 Tretinoin disrupts wart's skin cell growth. (cream
or an oral medication)
 Bleomycin used with caution to kill the virus.
Risks of this therapy include nail loss and
damage to the skin and nerves
 5-Fluorouracil is a chemotherapeutic agent
which can be used topically
 Benzalkonium is cationic surface-acting agent