Effect of electric current on the stability of aqueous solution of amitriptyline HCl, amoxicillin, cefuroxime sodium and dexamethasone 21 phosphate disodium salt

Iontophoresis is a penetration enhancer technique that uses a mild electric current to increase the penetration of charged ions through the skin. In order to avoid any damage to the skin the current density generally selected for iontophoresis is within the range of 500muA/cm2. Usually, the current is kept constant and the potential is changed to account for changes in the resistance of the skin. The passage of electric current may induce oxidation or reduction of the ions in solution. Therefore, not every compound is suitable for iontophoresis delivery and its stability to electric current must be assessed. If the redox potentials of the compounds are know, it is easy to predict if the reaction will take place or not. However, the redox potential depends on a number of factors and it is difficult to measure experimentally or it requires equipment that is not available in our laboratory as Cyclic Voltammeter. An alternative approach is to monitor the stability of the compound by measuring its concentration during the delivery of electrical current. This is the approach used in this project.;The purpose of this thesis was to study the effect of electric current on the stability of four compounds that are possible candidate for iontophoresis delivery. (1) Amitriptyline hydrochloride, (2) Amoxicillin, (3) Cefuroxime sodium, (4) Dexamethasone 21 phosphate disodium salt. Amoxicillin and Cefuroxime belongs to a class of beta-lactam antibiotics where as Amitriptyline is Tri-cyclic anti depressant and Dexamethasone is a steroidal anti-inflammatory drug.;In this project steel electrodes were used to be consistent with the in-vivo iontophoresis studies performed in our laboratory.;A unique experimental method was developed to perform this experiment. Steel patch was separated from its plastic cover and cotton cloth by crushing. For each drug, the experimental set up and the method was kept constant only the current density was varied so as to study the effect of only the current. 150 ml of an aqueous solution of a drug was made which was known to have a theoretical concentration of 20ug/ml. The drug solution was divided among three beakers, each having a 50 ml drug solution. Electrodes were dipped inside and were connected to a constant current (D.C.) supply source. Two sets of beaker were provided with a required current density whereas a third set of beaker was kept as a control without any current supply. A sample of 200W was taken from each set at a defined interval and analysed for drug concentration in HPLC. The HPLC method was selected and validated separately for determination of each drug. Each drug was tested for the effect of three different current densities (100, 200 and 3001.1A/cm2).;The results showed up to 6.4% decrease in the drug concentration for current treated samples compare to the control samples. The effect of the current density or the time on the drug degradation was significant for some of the drugs tested.