EEI 10/24b Iontophoresis Flashcards
neutral atom
protons = electrons
positive ion
protons > electrons
negative ion
protons < electrons
solvent
breaks down solute
-saliva is a solvent and breaks down our food
electrophoresis
ionic movement according to the electrically charged current acting on it
positive ions
cations
negative ions
anions
cathode
negative electrode
lots of cations want to stick to it
anode
positive electrode
attracts negative
three main pathways for ionto
- Paracellular (between cells)
- Transcellular (through cells)
- Appendageal (along pores: hair follicles, sweat glands, etc)
positives for ionto rather than injection
- non-invasive
- less risk of infection
- more local/less systemic
define iontophoresis
use of low amplitude direct current to administed ionized medications across the skin
typical substances that travel on ionto
anti-inflammatories
local anesthetics
what is the typical current range of ionto device?
1-4 mA
drug delivery mechanisms
electrophoresis (main technique clinically)
electro-osmosis
electroporation
define electroporation
process by which a large transmembrane voltage temporarily disturbs the phospholipid bilayer membranes, creating a “pore” through which molecules can pass
-within stratum corneum
electroosmosis
movement of a solvent, carrying with it other dissolved substances, through the skin under the influence of direct current
-same direction as the flow of counter ions
> at physiologic skin pH (~7); skin carries a negative charge, counter ions are positive
electro-osmosis electrodes
anode (+) medication = enhanced
cathode (-) medication = hindered
advantages of iontophoresis
non-invasive get local reaction, decreased systemic painless (itching or slight tingling) avoids tissue damage decreases side effects - maybe
disadvantages of iontophoresis
the amount that gets to the target tissue (biggest factor) is less known
can get burns from DC current
for pain, which drug do you take and what charge is it
lidocaine
(+) charged
for calcium deposits, which drug do you take and what charge is it
acetic acid (-) charged
for inflammation, which drug do you take and what charge is it
dexamethasone
(-) charged
for pain, overuse, and arthritis which drug do you take and what charge is it
sodium salicylates (-) charged
what is dexamethasone best for?
itises
-plantar fasciitis, lateral epicondyle, rotator cuff tendons, infrapatellar tendon, tib. post. tendon, etc
electrochemical effects of DC current
AABC - acid anode, basic cathode
what effects do DC anodes have on the body
Acidic
caustic HCl
hardens tissue
accelerates tissue growth
decreases nerve excitability (HYPERPOLARIZATION)
increases capillary coagulation (restricts BF)
what effects do DC cathodes have on the body
Basic
caustic NaOH
softens tissue
bacteriostatic effect (keeps area clear of bacteria)
increases nerve excitability (DEPOLARIZATION)
promotes vasodilation
what are the current, duration, and pH targets with cathode DC current
current 2-4mA
duration 30 min
pH change from 7 to 10.1
medication of ionto is driven due to
- amplitude of current (1-4 mA)
- duration of treatment (20-40 min)
- total current dosage (mAxmin = 40-80mA*min)
- polarity (medication dependent)
if current density has to be less than 0.5mA/cm2, for a 2x2 electrode what is the maximum amplitude you should provide?
current density = current/area
current = current densityxarea
=2.0mA as the peak amplitude
what happens if the maximum calculated amplitude is 6mA?
devices normally don’t go over 4mA, so we wont utilize that current
how do you know which dosage is best?
research is not there to justify one vs the other, but it depends on the patient’s needs, schedule, and sensitivity
what is the best factor to utilize with penetration of the drug into the skin?
TIME ELAPSED
- current intensity does not matter
- after 20minute treatment, leave on patch for another 5-6 hrs to continue flow
penetration of the ions is the ___ in the region of the ___, it is in proportion to the ____ magnitude, and it is most likely deposited below the _____. Onward migration to the ___ tissues is achieved by ____ rather than being ___ ___ by the current
greatest pores current stratum corneum deeper diffusion over time driven/ionto'd deeper
how to set up electrodes
- active - delivery electrode, medicated
- return - dispersive electrode (to finish circuit)
- polarity - cathode (- lead) to deliver (-) medicine; anode (+ lead) to deliver (+) medicine
what lead does dexamethasone go under when delivering ionto
cathode (-)
what don’t you want to do when delivering ionto?
- ultrasound (Increases blood flow - so would be contra to the ionto)
- heat/ice (During heat, BF increases and with Ice vessels constrict but when you take it off it triggeres BF back to tissue so it’s not good!)
- short wave diathermy (waves and heat)
- massage
- exercise
what do you want to consider for the patient when delivery ionto
Keep the medication in the location that we want!
Want to avoid increased blood flow to the area
Do ionto at the end of the treatment
clinical considerations for ionto?
- drug allergies (to NSAIDs and others - contact physician)
- size of affected area (targetted, small, and superficial; thumb>hamstring)
- depth of penetration (increase duration)
- contraindications and precautions (same as stim)
- broken, damaged skin
- reduced sensation
- pacemaker, bladder stimulators, phrenic nerve stilumators
do you directly start with 4 mA of current on a new patient?
No, begin with 1 or 2 then progressively crank up to 4
possible skin reactions from ionto
- mild skin reaction - not a burn; some erythema
- small blister-like vessicles may appear and resolve in minutes to hours (if doesn’t resolve, don’t do treatment again)
- abnormal response: bright white spots
inflammation and ionto
use dexamethasone -> deliver with cathode for lateral epicondylitis, carpal tunnel syndrome, de Quervain synovitis, planta fascitis
Side effects:
- break down of collagenous tissue (muscle, tendon, bone)
- don’t do every day
- if not effective in 3-4 treatments STOP
what is the big risk with anesthetizing the skin with lidocaine?
delivered with anode, skin becomes numb, increased risk of electrical or chemical burns
