Transdermal Iontophoresis of Vitamin B12 Under Three Different Skin Preparations

In order to quantify the changes in skin permeability to drugs delivered by ION under three different preparatory conditions, we used V.B12 as a model substance. Its choice was dictated by its inherent safety, positive charge and quantification of serum concentration readily available through our clinical laboratory. We compared the effects of unprepared skin (No Prep), oil-soaked skin [ref. 9-12] (Oleic Acid) and skin from which hair have been plucked out of (Epilation), on the serum concentrations of V.B12 before and after administration via ION.

Veterans and non-Veterans without SCI were recruited for the study comparing the three skin preparation methods. This prospective, skin preparatory method sequence-randomized study was approved by the Institutional Review Board of the James J. Peters VA Medical Center (JJPVAMC). The ION equipment used was a standard FDA-approved wired ION controller unit (IBOX by Dynatronics) and 4mL ION electrodes by (ionto+ by Richmar). The skin was prepared using 1 of the 3 techniques, performed in a random order. Each subject was assigned a 2-digit sequential number. A random-numbers table was used to assign the sequence of methods to each subject. A single positive electrode patch containing 4mL of a water-based solution with 15mg of V.B12 was used per experiment. One negative electrode patch was also used to complete the circuit. Blood was drawn prior to the first administration. Thirty minutes after the start of the ION delivery of the V.B12 through the skin of anterior thigh, the blood was drawn again. The blood was centrifuged for 5 minutes and delivered to the clinical laboratory for testing without delay. Serum concentration of V.B12 was measured using chemoluminescence on an automated laboratory reader Advia Centaur-XP. The experiments were conducted sequentially in a timely fashion, performed on the same day and within a span of 3 hours. Blood was drawn for a total of 4 times per subject.

The "No Prep" technique was performed by simply wiping the two skin surfaces on an anterior thigh, where the electrodes were later attached, with two-70% isopropyl alcohol prep. pads. The skin surface destined for positive electrode application was sprayed with a thin layer of 20% Benzocaine (Americaine aerosol spray can) and covered with an occlusive plastic film for 10 minutes. The film was then removed and the skin was cleansed with water-moistened paper towel, followed by one alcohol prep. pad.

The "Oleic Acid" technique involved first wiping the two skin patches and later soaking the skin patch, where the positive electrode was going to be placed, with oil called oleic acid for 40 minutes. The oil was then wiped off with a paper napkin and an alcohol pad. That same skin area was sprayed with a thin layer of 20% Benzocaine (Americaine aerosol spray container) and covered with an occlusive plastic film for 10 minutes. The film was then removed and the skin was cleansed with water-moistened paper towel, followed by one alcohol prep.

The "Hair Epilation" technique involved first wiping the two skin patches with 2-70% isopropyl alcohol skin preps and sprayed with a thin layer of 20% Benzocaine (Americaine aerosol spray container) and covered with an occlusive plastic film for 10 minutes. The film was removed and the skin was cleansed with de-ionized water followed by alcohol prep. Hair removal, using an epilator machine (Remington EP 7030), was performed by clearing an area of 5x5cm or 2x2 inch square. The epilated area was then covered with a thin layer of 0.2% Sodium Lauryl Sulfate (SLS) in de-ionized water.

After each of the skin preparations and without delay, 15mg of methylcobalamin dissolved in 4mL of de-ionized water soaked into the anode patch reservoir was applied to the designated skin of the proximal anterior thighs. The 7x7cm skin area under the negative electrode was wiped with an alcohol pad and 0.5mL of 1% citric acid dissolved in 0.9% normal saline solution was applied to the negative electrode's skin contact surface. The return (negative) electrode was then attached to the skin 10cm from the positive electrode.

An elevated room temperature of 73-78 degrees Fahrenheit (25 degrees Celsius) was maintained in the room for the purposes of maintaining adequate blood flow in the peripheral dermal capillaries. No exclusion criteria for diseases that decrease capillary perfusion such as diabetes have been utilized. As a result, 2 of the 10 subjects who participated in this study had a diagnosis of Diabetes Mellitus type 2.

IBOX ION device was attached to the electrodes by way of wire leads and a multimeter was attached to the electrodes in parallel in order to record the skin's electrical resistivity prior to and after ION. Throughout the 20-minute ION session, voltage exerted by the IBOX was recorded at regular intervals. The voltage was automatically adjusted by the IBOX to deliver a pre-set constant electrical current of 4mA/minute. Throughout the procedure subjects were asked about the presence of any sensations associated with the ION including effects of the medication being administered.