presentation 3
TRANSCRIPT
Introduction To Iontophoresis
DefinitionUsed forPhonophoresisComplicationsAdvantages over phonophoresis
Route Of Iontophoretic Drug DeliverySKINThe largest organ of the human body.Weight=about 15% of body weightSurface area=1.5 –2.0 square metersThickness=2-3mmSweat glands=650 average square inch of skinBlood vessels=20Melanocytes=60,000Nerve endings=more than a 1000
Diagram Of The Layers Of Human Skin
Mechanism Of Iontophoretic Drug Delivery Via Skin
o Skin consists ofo Lipids(15-20%)o Protiens(40%)o Approx. Water(40%)
o Patch Applicationo Alteration Of Molecular Rearrangemento Skin Permeability changeso Flip-Flop Gating mechanismo Isoelectric point of Skino Electro-osmosis
Principle Of Iontophoresis
Like & unlike charges
Negatively charged drug
Choice of drug
Compounds That Have Been Iontophoresed
Model Compound (s)
Indications and Applications
In vivo. Human
Morphine Postoperative analgesia
Metoprotol Hypertension
Lidocaine Skin puncture anesthesia Acyclovir Herpes orolabialis Penicillin Burn sterilization Fluoride Dentin hypersensitivity Hydrocortisone Arthritis Insulin Cystic fibrosis Tap water Hyperhidrosis
Compounds That Have Been Iontophoresed
Model Compound (s)
Indications and Applications
In vitro,excised skin
Propranolol Drug administration rate
Azidothymidine Iontophoresis enhancement
LHRH Skin peptide metabolism
Vasopressin Factors rate affecting delivery
Amino acids Factors affecting delivery rate
Piroxicam Drug administration rate
Factors Affecting Iontophoretic Transport
o General Factors likeo physiochemical properties of the compound o drug formulationo equipment usedo biological variationso skin temperatureo duration of iontophoresis.
Factors Affecting Iontophoretic Transport
o Current Strengtho Ionic Competitiono Drug Concentrationo Molecular Sizeo Convective Or Electro-
osmotic Transporto Current-continuous Vs.
Pulsed Modeo Physiological Factorso Influence of pH
Advantages
o Over Oral Administrationso Over Parenteral Therapyo Therapeutic Efficacy o Dosing o Short Biological Half-lifeo Simplified Therapeutic Regimeno Rapid Termination Of The Medication.
Disadvantages o Minor Reactions
o Long-lasting Skin Pigmentationo Need Of Aqueous Solution And Must Be
Ionizedo Limit To The Quantity-Usually more than 5 To
10 Mg/Hr Causes Burns To The Underlying Skin.
o Skin Itself A Barriero Isolated Report
Efficiency Of Iontophoretic Drug Delivery
The total iontophoresis current can be written as the product of electrode area A(cm2) and the current density id (mA/cm2). Thus,MD = ED ID A M W X t ZD x F
where MD = Dosage of the drugD (Quantity/time)F = Faraday's constant (96,500 coulombs/mole)ZD = Valence(Unitless) Mw = Molecular weight (g/moles)t = time (seconds)iD = current carried by drug ions.
Hence this equation allows to calculate how much drug can be delivered by iontophoresis.
Iontophoretic Drug Delivery Device
An iontophoretic system has three basic components : the source of electric current- consists of a battery and control
electronics An active reservoir system- consists ionic therapeutic agent an indifferent or return reservoir system- contains an electrolyte
and serves to complete the electric circuit.
Vytris Iontophoretic PatchPositively charged drugs placed at the anode Return reservoir, placed at the cathode, which contains saline solution. A battery and microprocessor connect the anode and cathode reservoirs,
which are both in contact with the skin when the patch is applied.the current is switched on the positively charged drug molecules are forced away from the anode through the skin to the capillary bed below, in exchange for chloride ions At the cathode, chloride ions from the saline solution are forced away into
the capillary bed, and sodium ions are drawn up from the body fluid. For negatively charged drugs, the anode and cathode are reversed with respect to the drug reservoir and the return reservoir.Drug flux is proportional to current but is also dependent on the molecular
size and structure of the drug, its charge, the concentration of the drug, the presence of competing ions or permeation enhancers in the formulation, the area of the patch, and the integrity of the skin/patch interface.
ALZA
W/Alligator Clip Lead Wires Model Pm900c
Weight-4 oz Width-21/2” Length-41/2” Components-
Lead wires 9V alkaline battery Instruction guide
Transq-1gs (6 Kits) Model 031 Top reasons to choose TransQ®
Electrodes:No chemical buffers necessary Improve your drug delivery efficiency Deliver effective results in as few as three
treatments—fewer treatments mean more efficient service delivery Convenient peel-away window provides
for easy-fill, no-stick handling. TransQ-1GS Active Area: 7.6 sq. cm
Fill Volume: 1.5 cc Max. Current: 4.0 mA Rec. Dosage: 24-40 mA-min Max. Dosage: 80 mA-min Skin Interface: GelSponge™ Conductor: Conductive Element
Price $59.95
Model 033 • Active Area: 11.2 cm 53 cm• Fill Volume: 2.5 cc N/A• Max. Current: 4.0 mA • Rec. Dosage: 40 mA-min
Max.• Dosage: 80 mA-min • Skin Interface: GelSponge™
Carbon• Conductor: Silver-
SilverChloride Carbon • Price $119.95
Phoresor II Auto
Phoresor II Auto Safety And Convenience Features
• Description • Display Help • Automatic Time Calculation • Automatic Current Ramp Up • Automatic or Manual Current Ramp Down. • Pause • 10 Minute Automatic Shut Off • Resistance Limit • Dose and Current Limit • Electrode Reject
Setting Up The Phoresor II Auto
Preparing Electrodes And Patient For Treatment
NOTE : Please refer to directions for use supplied with electrodes for detailed instructions. DO NOT tape, bind or compress either electrode against the skin during treatment. Doing so may cause excessive skin irritation or burns.
Skin must be free of damage Preparation of drug electrode
For local Dermal Anesthesia For Other Medication
Preparation of skin sites Application of drug electrode Application of dispersive pad Attachment of twin lead connector clips
Operating The Phoresor II Auto
Normally , a typical treatment requires only three steps :
Select dose Set current Start
treatment
In PIIA Selecting dose Setting current Starting current Pausing or stopping
treatment manually Stopping treatment
automatically After treatment
Duration And Intensity Of Current Faraday’s law.The time for iontophoresis ideally is 1 minute for
the increasing phase and 30 seconds for the decreasing phase. The intensity of the current used is between 40 mA and 10 mA regulated with a 25000 ohm potentiometer. Currents ranging from 5 to 10 mA have been found to be painless. The intensity of current should not exceed 0.5 to 1mA / cm2 for large electrodes.
Effects Of Current On The Body In the Frequency range of 10-200 Hz, the body
is most susceptible to the effects of current. To the exposed healthy canine heart, currents
as low as 20 mA ( 60 Hz rms) can cause fibrillation .
Current greater than 2A can cause temporary cardiac arrest and paralysis.
Current greater than 6A can cause cardiac arrest, paralysis and deep burns.
Optimising Iontophoretic Transport
Variation in applied current density and area of application
pH optimizationCleaning of skin area
Contraindications for lontophoresis
Contraindications for iontophoresis are important in patients with higher susceptibility to applied currents. Such patients include those carrying electrically- sensitive implanted devices such as cardiac pacemakers, those who are hypersensitive to the drug to be applied, or those with broken or damaged skin surfaces.
In-vitro Evaluation
In-vivo Evaluation
Morimoto et al. (1992) described an in-vivo iontophoretic system used in rats for transdermal iontophoretic delivery of vasopressin and analogue in rats. A hypotonic solution was administered through the femoral catheter as a constant infusion. Two cylindrical polyethylene cells were attached to the abdominal skin of the rat. A pair of Ag/AgCI electrodes was immersed in the solutions, the anode being in the drug solution and thej;athode in the 0.9% w/v NaCl solution. The electrodes were connected to a constant current power sourcfe.
CONCLUSION: Iontophoresis involves delivery of selected ions into tissues by
passing a direct electrical current through a medicated solution and the patient.
This method of drug administration has many advantages Systemic side effects of drugs are significantly decreased because
only minute amounts of drugs are delivered, while a relatively high drug concentration is administered locally where it should achieve the maximum benefit.
Patient acceptance is generally excellent and fear of injection is eliminated. Thus, iontophoretic transdermal delivery has the potential of improving the quality of drug therapy compared to conventional methods of oral drug administration or bolus intravenous injection because it can minimize dosage while maintaining a constant therapeutic level by continuous drug input.
Scope For Future Work 1.Development of an ideal membrane, and an
animal model.2.Development of a foolproof method of measuring
skin resistance, and feedback of the electrical parameters to the device being used, which can adjust the drug delivery rate accordingly.
3. Miniaturization and cost-reduction of the device.4.Mathematical models to extrapolate the results of
animal experiments to clinical situations.