Iontophoresis Flashcards
What is it?
Transdermal drug delivery using low voltage direct current to move ions across a dermal barrier
does iontophoresis “drive” ions through the skin?
more recent literature points to the fact it more likely increases permeability of corneum stratum
Depth of penetration
- 3-20 mm
- may be linked to molecular structure being moved
why is medication placed in aqueous solution?
- To dissociate into + and - ions
- Low volt direct current can then use polarity to move these ions
- So you need to know if medicine is + or -
Mechanisms of ion transfer
- electromigration
- electroporation
- electroosmosis
Electroporation
- Increase in porosity of epidermis in response to e-stim
- skin is hydrophobic
- after e-stim, there is a temporary increase in skin porosity
Electromigration
- movement of ions into tissue
- based on “volume flow” and not just diffusion
Electroosmosis
- human skin has a net (-) charge
- Ions moving from + to -
So, for + charged ions, this may enhance the delivery of ions as they are “going with the flow” and hinder movement of (-) ions
What is the driving force behind iontophoresis?
repulsion of like charges
what polarity do i use?
- positively charged ions will be repelled by the positive pole (anode)
- negatively charged ions will be repelled by the negative pole (cathode)
Dosage
- 20 mA mins to 160 mA mins
- 40 mA mins and 80 mA mins most common
- this information given by the prescriber
intensity
To tolerance
Most units do not exceed 4 mA
what drives the time of the treatment?
intensity (mA)
Skin reaction - cathode
- sodium hydroxide can form under the cathode
- caustic
- known as an “alkaline reaction”
skin reaction - anode
- hydrocholoric acid can form under the anode
- known as an “acidic reaction”
- slightly more comfortable than the alkaline reaction
Current density should not exceed:
0.5 mA/cm2 for the cathode (-)
1.0 mA/cm2 for the anode (+)
** Not usually a problem with commercial units
what type of set up should you always use?
monopolar
electrode placement - active
+ or - based on the medication type
smaller electrode
place directly over treatment area
electrode placement - dispersive
opposite of active
larger electrode
place at a distance from active (usually proximal)
Acetic Acid (acetate)
(-)
purpose: calcium deposits
Dexamethasone
(-)
purpose: inflammation
Iodine
(-)
purpose: scars
Lidocaine
(+)
purpose: anesthetic
Precautions and Contraindications
- stimulation across chest
- pacemaker
- over carotid sinuses
- uncontrolled hypertension
- PVD
- thrombophlebitis
- pregnancy
- impaired sensation
- confused patients
- uncontrolled seizures
- obesity
- cancer
Treatment Procedure first things first
- select appropriate medication for the condition
- inspect skin for cuts, abrasion, scars, etc
- check sensation
- check for other contraindications/ precautions
- instruct patient about the treatment (why, how, what to expect)
Treatment procedure - set up
- position pt for comfort
- clean and prep skin
- prepare active electrode by placing meds on pad with syringe
- place active electrode over treatment area
- place dispersive electrode at a distance from active
- connect lead wires
- turn on device
- set dosage
- allow ramp of intensity if indicated by unit
- turn up intensity based on tolerance
- terminate and remove electrodes
after the treatment
- remove electrodes
- inspect skin
