Transungual drug delivery system

TRANSUNGUAL DRUG DELIVERY
SYSTEM
Prepared By : Apoorva Bauskar
F.Y M. Pharm QAT Sem II
Roll No : 517
Guided By : Dr S.P. Mahaparale
1

CONTENTS• Introduction
• Composition of Human Nail
• Anatomy of Human Nail
• Nail Diseases
• Nail Sampling
• Factors Affecting Permeation Through Nail Plate
• Techniques to Enhance Nail Penetration
 Mechanical Methods
 Physical Methods
 Chemical Methods
• Medicated Nail Lacquers
• Advantages
• Disadvantages
• Recent Advances
• Marketed Formulations
• References
2

INTRODUCTION
• Trans” means “through” and “ungual” means “nails”.
• So, transungual drug delivery system is nothing but a system
associated with drug delivery through the nail to achieve a
target drug delivery system of the nail to treat diseases of
nail.
• The hardness and the impermeability of the nail make it an
unpromising route for the drug delivery.
• Topical therapy is highly desirable due to its localized effects,
which results in minimal adverse systemic events and
possibly improved adherence.
• Nail plate is responsible for penetration of drug across it.
• As it is hard enough the penetration becomes difficult, only a
fraction of topical drug penetrates across it. Hence the
effective therapeutic concentration is not achieved.
3

• In order to successfully deliver active pharmaceutical
ingredients (APIs) across the nail it is necessary to consider
the anatomy and physiology of barriers to obtain the right
amount of drug to the right place at the right time more
effectively.
• Nail plate is the visible part of the nail which is responsible
for penetration of drug across it.
4

COMPOSITION OF HUMAN
NAIL
• Chemical composition differs from other body membranes.
• Nail plate : keratin molecules with disulphide linkages & low
lipid levels.
• It tends more like a hydrogel than lipophilic membrane.
5

• Nail Matrix : Also called the root of nail is posterior or
proximal part of the nail lies beneath a fold of the skin.
• Cuticle or Eponychium : Living skin covers
approximately 20 % of the nail plate.
• Paronychium: It is the skin that overlies the nail plate
on its sides.
• Hyponychium: Farthest or most distal edge of the nail
unit.
• Nail plate: Made of keratin; a special protein that
creates the bulk of the nail plate.
• Nail bed: Area of pinkish tissue that supports the entire
nail plate.
i. The deeper dermis - the living tissue fixed to the bone
which contains capillaries and glands.
ii. The superficial epidermis - the layer just beneath the
nail plate which moves forward with the plate.
7

• Nail Sinus (sinus unguis) : Deep furrow into which the nail
root inserted.
• Free margin (margo liber): Anterior margin of the nail plate
corresponding to the abrasive or cutting edge of the nail.
• Perionyx : Projecting edge of the eponychium covering the
proximal strip of the lunula.
• Nail Wall (vallum unguis) : Cutaneous fold overlapping the
sides and proximal end of the nail.
• Lateral margin (margo lateralis): It is lying beneath the nail
wall on the sides of the nail and the nail groove or fold (sulcus
matricis unguis) are the cutaneous slits into which the lateral
margins are embedded.
8

NAIL DISEASES
Onychomicosis Onychogryposis Nail Psoriasis
Paronychia Yellow Nail Syndrome Onychatrophia
9

Leuconychia Koilonychia Melanonychia
Onycholysis Onychorrhexis
10

NAIL SAMPLING
• Drug is initially applied to the nail dorsal surface.
Permeation is measured by sampling the solution on the
ventral nail plate at successive time points, and
calculating drug flux through the nail.
• It is similar to skin penetration studies.
• Skin penetration studies are not only for determination
of flux, but also include the separation of skin layers to
quantify drug concentration in each layer.
• A novel technique developed enables the determination
of drug concentration within the plate, where fungi
reside.
• This method relies on a drilling system which samples
the nail core without disturbing its surface.
11

• This is achieved with the help of a micrometer-precision nail
sampling instrument that enables finely controlled drilling
into the nail with collection of the powder created by the
drilling process.
• Drilling of the nail occurs through the ventral surface.
• The dorsal surface and ventrally-accessed nail core can be
assayed separately.
• The dorsal surface sample contains residual drug, while the
core from the ventral side provides drug measurement at the
site of disease.
• This method permits drug measurement in the intermediate
nail plate, which was previously impossible.
12

FACTORS AFFECTING PERMEATION
THROUGH NAIL PLATE
• Molecular Size of Compound : The permeability coefficient
decreases as the molecular weight increases. Thus for
optimal ungual permeation, drug molecules must be of small
in size and carry no electric charge on them.
• Degree of Ionization : Nail plate is less permeable to ionic
compounds than to their non-charged equivalents with
permeability coefficients.
• Nail Plate Hydration : It is an important factor for
determination of drug penetration. The permeation of
ketoconazole through excised human nails under different
relative humidity (RH) from 15 to 100% showed a 3-fold
improvement in the delivery of the radio labeled drug.
14

• Presence of intact dorsal layer : Overlapped cells
represent the greatest barrier to the drug penetration across
the nail plate. If this layer is partially or totally removed e.g.,
by debridement or chemical etching with 30-40% phosphoric
acid or use of keratinolytic enzymes, then drug permeability
increases.
• Binding of Drug to Keratin & other Nail Constituents
:Keratin is thought to have a pKa of around 5 and therefore
is positively and negatively charged at pH below and above
this result. It therefore may bind or repel molecules
depending on their charge. This may be part of the reason
for the lower nail permeability of ionic compounds.
• Nail Thickness : Thicker the nail the more difficult it will be
for drugs to reach the nail bed.
15

• Formulation Effects : pH affects the degree of ionization of
weak acids and bases which decreases their permeability
through the nail plate. It affects their solubility in formulations,
their ability to partition into the nail plate and their
interactions with keratin. The nature of the solvent will affect
nail hydration, drug solubility in the formulation and its
partition in the nail plate. There is also evidence that DMSO
improves permeability. Lacquers are thought to facilitate
delivery by drying to form a depot of drug on the nail.
• Nature of Vehicle : Replacing water with a non-polar
solvent, which does not hydrate the nail, is therefore
expected to reduce drug permeation into the nail plate.
16

TECHNIQUES TO ENHANCE
NAIL PENETRATION
Mechanical
•Nail Abrasion
•Nail Avulsion
Physical
•Iontophoresis
•Acid Etching
•Carbon Dioxide
Laser
•Hydration
•UV Light
•Micro-surgical
Lasers
Chemical
•Thiols
•Sulphites
•Water
•Keratinolytic
Enzyme
•Keratolytic
Enhancers
17

MECHANICAL METHODS
• Nail Abrasion : It involves sanding of the nail plate to thin
out its thickness or destroy it completely. Sandpaper of 150
or 180 can be utilized for sanding purpose. The sanding
must be performed on nail edges and should not cause
discomfort. An efficient instrument for sanding is a high-
speed (350 000 rpm) sanding hand piece. Nail abrasion,
using sandpaper nail files, prior to antifungal nail lacquer
treatment may reduce the critical fungal mass and thereby
aids in effective penetration. Nail abrasion thins the nail
plate, decreasing the fungal mass of onychomycosis, and
exposing the infected nail bed. It can enhance the action of
antifungal nail lacquer.
18

• Nail Avulsion : Total nail avulsion (surgical removal of
entire nail plate) or partial nail avulsion (partial removal
of the affected nail plate) is usually carried out under
local anesthesia. Keratolytic agents (urea or a
combination of urea and salicylic acid), which softens the
nail plate, have been utilized for nonsurgical nail avulsion
in clinical studies, prior to topical treatment of
onychomycosis.
Nail Avulsion
19

PHYSICAL METHODS
• Iontophoresis : It involves the use of electric field for the
delivery of a compound across a membrane. Drug diffusion
through the hydrated keratin of a nail can be enhanced.
Iontophoresis enhances drug penetration through the nail.
This is due to electro repulsion/electrophoresis- interaction
between the electric field and the charge of the ionic
permeant; electro osmosis convective solvent flow in pre-
existing and newly created charged pathways; and electric
field-induced pore inductions.
20

• Acid Etching : It involves application of surface-modifying
chemical etchants (10% phosphoric acid gel or 20% tartaric
acid solution) onto the dorsal surface of nail clippings to
modify the nail plate surface, resulting in formation of profuse
micro-porosities. These micro-porosities increase the
wettability and surface area and decrease the contact angle;
thereby provide an ideal surface for bonding materials. They
improve interpenetration and bonding of a polymeric delivery
system and facilitate inter-diffusion of topical therapeutics.
• Carbon Dioxide Laser : It involves penetrating the nail plate
with carbon dioxide laser beam followed with daily topical
antifungal treatment, penetrating laser-induced puncture
holes.
22

• UV Light : It involves heating the nail, exposing it to UV light,
and subsequently treating with topical antifungal therapy.
• Micro-surgical Lasers : It consist of microsurgical laser
apparatus which makes holes in nails; topical antifungals can
be applied in these holes for onychomycosis treatment.
• Hydration :Hydration may increase the pore size of nail
matrix, & enhances the transungual penetration. Hydrated
nails are more elastic and permeable.
23

CHEMICAL METHODS
• Thiols : These are the compounds containing sulfhydryl
groups (-SH), are the agents that reduce the disulfide linkage
in the keratin matrix of the nail.
• Sulfites : Incubation of nail plates with sodium sulphite could
reduce the nail plate’s barrier properties and enhance ungual
drug flux.
• Water : Nail hydration and swelling, on contact with water;
have been thought to be a probable mechanism for the
higher drug flux from aqueous vehicle.
• Keratinolytic Enzymes : These hydrolyze the keratin matrix
of nail plate, thereby altering its barrier properties and
subsequently enhancing the transungual permeation.
24

• Keratolytic Enhancers : Urea and salicylic acid are known
to soften and hydrate the nail plate. The swelling and
hydration of nail plate would enhance the drug permeation as
a consequence of the formation of a less dense structure with
large pores. Keratolytic agents were found to damage and
fracture the nail plate surface.
25

MEDICATED NAIL
LACQUERS
• These preparations are generally used in fungal diseases.
• Use of this system avoids oral toxicity of anti-fungal drugs.
• Medicated nail lacquers are the formulations that have
maximal antifungal efficacy as a transungual drug delivery
system.
• After application, the solvent from the lacquer formulation
evaporates leaving an occlusive film on which the drug
concentration is higher than in the original formulation.
• This increases the diffusion gradient and permeation through
dense keratinized nail plate.
26

EVALUATION OF NAIL
LACQUER
• Non volatile content
• Drying time and film formation
• Smoothness of flow
• Gloss
• Water resistance
28

ADVANTAGES
• It cannot be easily removed by rubbing or washing.
• Depot formation.
• In addition, the effect is long lasting; single application of
lacquer provides protection for one week.
• Release and rate of diffusion can be optimized by
selecting the components of lacquer formulation
(solvents, polymer, and plasticizer).
• Preparation is easy as compared to oral dosage form.
• Minimal or no systemic side effects.
• Considering nail pharmacokinetics a very small portion
of oral dose reaches nails. Localized therapy there by
helps in reducing dose.
29

DISADVANTAGES
• Rashes relate to adverse effects such as periungual
erythema and erythema of the proximal nail fold were
reported.
• Other adverse effects which were thought to be casually
related include nail disorder such as shape change,
irritation, ingrown toe nail and discoloration.
• It has to be applied regularly until all the affected nail
tissues have grown out. This takes 9-12 months for the
toe nails and 6 months for finger nails.
30

RECENT ADVANCES
• Mesoscissioning Technology : It creates a
micro‐conduit through the skin or nail within a specified
depth range. Fully open pathways can be painlessly
sized through the stratum corneum of the skin or through
the nail. Micro conduits, 300‐500 microns in diameter,
are produced within seconds and without sensation.
These pathways can be used to deliver drugs across the
skin.
Mesoscissioning Technology 31

• Nano Patch Nail Fungus : It uses AC/DC
electrochemistry and targeted drug delivery to actively
push antifungal drugs right through the nail cuticle to the
actual location of the fungus growth. This technology
targets nail fungus at its source of growth.
32

REFERENCES
• Firoz S, Naga Sirisha M. Transungual drug delivery
system -A review. International Journal of Innovative
Drug Discovery 2011; 1(1):914.
• Murdan S. Drug delivery to the nail following topical
application. Int J Pharma., 236, 2002, 1-26.
• Dawber, R.P.R., De Berker, D., Baran, R. Science of the
nail apparatus. In: Baran, R., Dawber, R.P.R. (Eds.),
Diseases of the Nails and their Management, 2nd Ed.
Blackwell Scientific Publications, London,1994: pp. 1–34.
• Bhapkar PH, Puttewar TY, Patil R.Y., Nail Lacquers in
Nail Diseases. IOSR Journal of pharmacy 2013; 3(9):24-
28.
34

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