|
Definition
Iontophoresis is an effective and painless method of delivering medication
to a localized tissue area by applying electrical current to a solution of the
medication. The delivered dose depends on the current flowing and its duration.
Overview
Iontophoresis is a recognized therapeutic method for delivering ionic compounds,
i.e. drugs, into and through the skin by applying electrical current. It has proven
to be a beneficial treatment for many localized skin disorders such as; nail diseases,
Herpies lesions, psoriasis, eczematous, and cutaneous T-cell lymphoma. The method
has also been reported useful for topical anesthesia to the skin prior to cut-down
for artificial kidney dialysis, insertion of tracheotomy tubes and infiltration
of lidocaine into the skin prior to venipuncture. Treatment of various musculoskeletal
disorders with anti-inflammatory agents has been reported in the literature. Iontophoresis
enhances the transdermal delivery of ionized drugs through the skin's outermost
layer (stratum corneum) which is the main barrier to drug transport. The absorption
rate of the drug is increased, however, once the drug passes through the skin
barrier natural diffusion and circulation are required to shuttle the drug to
its proper location. The mechanism by which iontophoresis works is based upon
the knowledge that like electrical charges repel. Application of a positive current
from an electrode to a solution applied to a skin surface will drive the positively
charged drug ions away from the electrode and into the skin. Obviously, negatively
charged ions will behave in the same manner. Introduction
The
method of iontophoresis was described by Pivati in 1747.Galvani and Volta, two
well-known scientists working in the 18th century, combined the knowledge that
electricity can move different metal ions, and that movements of ions produce
electricity. The method of administrating pharmacological drugs by iontophoresis
became popular at the beginning of the 20th century due to the work of Leduc (1900)
who introduce the word 'iontotherapy' and formulated the laws for this process.
Iontophoresis is defined as the introduction by means of a direct electrical current,
of ions of soluble salts into the tissues of the body for therapeutic purposes.
It is a technique used to enhance the absorption of drugs across biological tissues,
such as the skin. Another method for drug delivery through the skin, called phonophoresis,
uses ultrasound instead of an electric current. Both these techniques are complicated
because of other processes that occur simultaneously with the delivery of the
drug. With the present knowledge about these processes, it is easier to select
and prepare appropriate drugs and vehicles for iontophoresis than for phonophoresis.In
clinical practice, iontophoresis devices are used primarily for the treatment
of inflammatory conditions in skin, muscles, tendons and joints, such as in temperomandibular
joint dysfunctions. More recently, iontophoresis has been used in combination
with laser Doppler technology as a diagnostic tool in diseases comprising the
vascular bed. Principles
of iontophoresis
AsBy definition, iontophoresis
is the increased movement of ions in an applied electric field. Iontophoresis
is based on the general principle that like charges repel each other and unlike
charges attract each other.An external energy source can be used to increase the
rate of penetration of drugs through the membrane. When a negatively charged drug
is to be delivered across an epithelial barrier which is placed under the negatively
charged delivery electrode (cathode) from which it is repelled, to be attracted
to the positive electrode placed elsewhere on the body. In anodal iontophoresis
(positively charged ions), the electrode orientation is reversed .The choice of
drug is of importance depending on whether the compound is unionised or ionised.
Non-ionised compounds are generally better absorbed through the skin than ionised
substances. The penetration across the skin or other epithelial surfaces is usually
slow due to their excellent barrier properties. Many drug candidates for local
applications only exist in an ionised form, which makes effective membrane impossible.
<<back |