Dermal Reduction of Urushiols Using an Activated Charcoal Formulated Dermal Care Patch

For centuries, activated Charcoal (AC) has been used externally in a poultice form to adsorb “poisons” trapped in the outer layers of skin and internally to relieve intestinal discomfort and to remove toxic materials. The largest use for activated charcoal, in our society, is as a filter bed in air and water remediation cartridges. Recently, scientists have formulated AC into a nonstick dermal bandage called the Charcoal Patch (CP), but the adsorption properties are not well understood for this new formulation. Experiments have been conducted to see if these dermal bandages can be used to adsorb oils such as poison ivy and other toxic oils. Since poison ivy is an extreme dermal irritant, experiments were performed with a surrogate compound, 3Pentadecylphenol (3-PDP), which has a similar chemical structure to urushiol, the active irritant in poison ivy. The main goal of this research is to reduce the amount of urushiol that is absorbed by the skin by using an activated charcoal dermal patch. This particular project’s objective is to determine the characteristics and quantity of materials that can be adsorbed and contained in a dermal patch. Experiments were conducted by cutting out square pieces of the charcoal patch and measuring the mass gained by various substances over varying amounts of time using a precision analytical balance, capable of recording mass changes down to 100 μg. The amount of substance being adsorbed in grams per gram of CP is calculated and compared among different analytes. This is the first stage in determining the effective adsorbing ability for nonpolar analytes using charcoal that is integrated into a non-messy, non-stick dermal bandage. Introduction Activated Charcoal (AC) has been used for centuries in a poultice form to adsorb “poisons” trapped in the outer layers of skin. Activated charcoal is the highly porous form of carbon, which imparts a surface area within these particles to nearly 500 m per gram of charcoal. Its hydrophobicity, high surface area, and low cost have made it an effective choice absorbing hydrophobic materials from water and air. It can also be taken internally to adsorb toxins that may have been ingested. Activated Charcoal is rated “Safe and Effective” (Category I) by the FDA for acute toxic poisoning. Activated Charcoal has also been used to aid in drawing out toxins in overdose patients and is recommended by the Poison Control Center. It is listed in the U.S. Pharmacopoeia and is recognized as the universal antidote. Activated Charcoal does adsorb most organic and inorganic chemicals, and does not adsorb beneficial nutrients. Past experiments conducted have shown activated charcoal to be harmless on the skin and to cause no illside effects. Some experiments that were performed involved mixing activated charcoal with Cobra venom and injecting it into to a laboratory animal. The animal was not harmed showing the charcoal did adsorb the toxin and essentially inactivated the toxin. Other experiments involved mixing the activated charcoal with arsenic and strychnine to be ingested by humans under laboratory conditions. Subjects had survived despite the dosage being 5 to 10 times lethal. There have also been experiments that tested the adsorptive properties of activated charcoal showing that it can adsorb phenolic compounds under different isothermic condtitions. AC has also been shown to adsorb highly toxic oxyanions, but through modification with a cationic surfactant. It is an adsorbent capable of binding other substances in a relatively large amount onto their surface. This property is often used in pharmacy as well as in the studies of the structure, biological activity relationships, where active charcoal serves as a model substance for the study of hydrophobic interactions. The adsorptive properties of AC have been investigated involving basic esters of phenylcarbamic acid with a local anesthetic effect. Activated charcoal is made from burning carbon rich sources such as woods, shells, and husks to name a few natural sources. There have been studies done in which activated charcoal was prepared from Aleppo Pistacia Vera shells using different percentages of zinc chloride at temperatures of 873 Kelvin in the absence of air. The different percentages of zinc chloride were found to affect the pore size of the activated charcoal created. Using gases such as steam or air at high temperatures, to oxidize insoluble carbonized wood, can also create activated charcoal. Dried coconut shells without meat, can also be used to create activated charcoal. These shells would need to burn at temperatures of about 600-900 degrees Fahrenheit, and then combined with 25 % concentrated solution of calcium chloride or zinc chloride for 24 hours. AC can be made from macadamia nut shells and coconut shells, by being heated at high temperatures to be carbonized then using oxygen in air oxidizes it. The removal of carbon mass by the development of pores is responsible for the increases in surface area of the activated charcoal. The mass of carbon removal is related to the pore size. Due to these properties of AC, we want to study if this recently made charcoal patch would exhibit the same characteristics of AC and if it could be used in the treatment of poison ivy exposure. We want to see if this charcoal patch would be effective in the dermal reduction of urushiols from skin. Experiments were conducted to determine if these dermal bandages could adsorb oils such as poison ivy and other toxic oils. Since poison ivy is an extreme dermal irritant, experiments were performed with a surrogate compound, 3-Pentadecylphenol (3-PDP), which is similar in structure and hydrophobicity to urushiol, the active irritant in poison ivy. Similar urushiols can also be found in poison oak and sumac. Experimental Section Charcoal patches (CP) and charcoal patch formulation (CP-formulation) were obtained from Neobiotech (Berrien Springs, MI). The charcoal patches were manufactured using a heated transfer of the CP-formulation onto a cotton fabric backing then covered by wax paper. The charcoal patch formulation was processed using activated charcoal and a proprietary set of additives and then blended into a homogenous mixture. This formulation can be placed on top of skin but not leave any residue when removed. The charcoal patch (CP) is the completed product comprised of CP-formulation and woven backing made of cotton. Materials needed for experiments performed include CP squares, tape, various substances and oils (listed below), glass plates, rulers, test tubes, Bunsen burner, Pasteur pipets, Erlenmeyer flasks (25 mL) and hot plates. Mass measurements were made on a Mettler Toledo (model AF166) analytical balance that measures to 0.1 mg. Mineral, vegetable, walnut, peanut, and fish oil were used as surrogate oils for poison ivy. These were purchased from a local food market and used without further modification. ACS reagent grade acetone, ethanol, 2-propanol, and heptanes were obtained from Sigma Aldrich and used as is. Activated charcoal powder (AC) and 3-Pentadecylphenol (3-PDP) were also obtained from Sigma Aldrich and used without modification. Methods Procedure 1: The first experiment was performed to determine the properties and characteristics of the AC relative to CP-formulation. This experiment was then repeated using activated charcoal powder, so that the properties of the AC could be compared with that of the CP formulation. 1. Obtain four test tubes, in two put a few milligrams of AC and in another two put a few milligrams of CP-formulation 2. In a each test tube containing AC and CP formulation add water. 3. In the other test tubes containing AC and CP-formulation add water + mineral oil. 4. Cover the test tubes with parafilm and leave for 24 hrs. Procedure 2: The next experiment involved using substances such as distilled water, heptane, mineral oil, acetone, 3-PDP, ethanol, and 2-propanol. This experiment was done in order to determine the adsorption properties these various substances in a short time frame to quickly screen materials. The outlined procedure is listed below. The charcoal patch was taped down to the plate glass to prevent substances from being absorbed by the cotton backing as well as to give an exposed surface area in which adsorption Is taking place. This ensures that the actual adsorption of the charcoal patch formulation is being observed. This procedure is similar to those of procedure 3, 5, and 6. It differs in that it is a more generalized procedure and the amount of substance that was added to be adsorbed was not measured; only the results were recorded. Procedure 3 is more specific and the amount of substance added has been recorded, the time intervals are longer, and the substances used have been narrowed down to specific oils. In procedure 5, a step is added in which the charcoal patch is pre-treated with water and soap to see if it will aid in the adsorption of oils. In procedure 6, a slygard, silicone gel is used instead of the tape. This was to test if previous results were accurate, and that charcoal patch formulation fibers were not being taken up with the tape. 1. Cut out about eight squares of charcoal patch squares about 3 cm by 3 cm. 2. Weigh and record the initial weight of the square. 3. Tapes the square to a plate glass with the charcoal portion faced upward, see Figure 2, and record the weight of the combination. 4. Place a drop of distilled water on another glass plate, then place the charcoal patch that is attached to the plate glass on top of the drop. Leave in contact for about 30 s. 5. Pick up the plate and dab the charcoal patch dry (If there is any excess liquid, make sure not to press too hard). 6. Weigh and record results. 7. Repeat steps 4-6 increasing the time intervals by 4 min. 8. Repeat steps 2-7 using the other substances listed above. Procedure 3: The experimental procedure more accurately determines the amount of substance in grams was being adsorbed per grams of the charcoal patch over a given time period. Based on the results from the previous experiment, specific substances can be used to study the adsorption of the patch. The main substances used included mineral oil and distilled water. Most of the experiments conducted used this basic procedure with few changes. Some changes involved Figure 2: Glass slide with CP taped down Figure 3: To the left, plate glass with tape, adhesive side up. To the right, plate glass with tape and charcoal, on adhesive side up. running experiments for 1 hr, 4 hrs, & 24 hrs. Other changes involved using different oils such as peanut oil, walnut oil, and fish oil. Experiments were also done with dish soap. 1. Cut out nine pieces of charcoal patch squares. 2. Weigh three charcoal patch squares and record. 3. Tape three individual squares to three individual glass plates. 4. Measure and record the exposed area of the charcoal patch squares. 5. Place two drops, approximately 1.0 g of distilled water onto each exposed area of the charcoal patch and place a glass plate over it. 6. After an hour, remove the glass plate (make sure to wipe off any excess water), and remove the tape from the patch. 7. Weigh and record the resulting charcoal patch. 8. Repeat steps 2-7 using mineral oil and vegetable oil. Procedure 4: This experiment was performed to determine how much oil could be adsorbed by activated charcoal powder. This experiment was also repeated with water to determine if water could be adsorbed by activated charcoal powder. 1. Put one piece of tape adhesive side up and tape down to a glass plate using two other pieces of tape adhesive side down. Figure 3. 2. Put two other pieces perpendicular to the other strips of tape to make an adhesive square in the middle. 3. Weigh and record the weight of the plate glass and tape. 4. Add charcoal powder and smooth down with lintless tissue wipe until there is a thin film of charcoal. Note: Try to make sure there isn’t much charcoal residue coming off the tape. 5. Weigh and Record the plate glass, tape, and charcoal. 6. Put two drops/approximately 1.0 g of mineral oil and wait for 2 min. 7. Wipe off excess oil, trying not to take up any charcoal powder. 8. Weight and record the results. 9. Repeat procedures 1-8, three times. Procedure 5: This experiment was performed to determine if adding water to the charcoal patch square will aid in its adsorption to oils. When results showed that water did not aid in oil adsorption, Figure 4: Plate glass with a charcoal patch with a slygard, silicone gel, on top. this experiment was conducted again using dish soap instead of water. Results showed that dish soap did not aid in the charcoal patch adsorption of oils as well. 1. Cut out four pieces of charcoal patch squares. 2. Weigh and record each square. 3. Tape down each square lightly and to individual glass plates measure and record the exposed area. 4. Add two drops/approximately 1.0 g of distilled water. 5. Remove the tape from the charcoal patch square, then weigh and record the patch plus distilled water. 6. Following the indention of the tape lines, tape back the charcoal patch square to the glass plate. 7. Add about two drops/ approximately 1.0 g of mineral oil and place a glass plate over it. 8. After an hour, weigh and record the resulting charcoal patch. Note: Make sure procedure is done with each charcoal patch square individually. Procedure 6: This experiment was performed to see if previous experiments were accurate, when determining the adsorption of the patch. Experiments were performed by taping down the sides of the charcoal patch squares and it was unknown if fibers of the patch were being caught on the tape. It was decided to perform procedure 2, using a slygard 184, silicone elastomer, which is a gel used instead of tape to make a well to prevent the oil from getting into the backing of the CP. 1. Cut out four charcoal patch squares, weigh and record. 2. Cut out four sylgard gel squares, and cut out a second square in the middle and measure and record the area. Figure 4. 3. Place one of the squares on a charcoal patch and add two drops/ approximately 1.0 g of Peanut Oil. 4. Place the smaller square on top of the oil and place a glass plate on top of it. 5. Leave for an hour. 6. Peel back the gel and record the resulting patch. 7. Repeat steps 3-6, with three other patches. Results Side by side comparison of AC and CP-formulation ability to absorb water and mineral oil. Utilizing Procedure 1, the CP-formulation and AC were evaluated in a side-by-side comparison. It is generally accepted that activated charcoal powder tends to adsorb oils, i.e. Figure 5: AC and CP-Formulation compared in test tubes containing water (A & D) or in a water-mineral oil mixture (B&C). Test tubes A and B contain AC while test tubes C & D contain CP-formulation. hydrophobic compounds, and does not adsorb water or hydrophilic compounds, ions, or metals. This first procedure was implemented to verify this behavior and to establish a correlation between AC and CP-formulation through a simple, side-by-side test tube comparison. This experiment compared the characteristics of AC to that of the CP formulation. Each material was placed in deionized water or a deionized water-mineral oil mixture. The charcoal based substances were added and some manual mixing (swirling or spatula) was utilized to mix the materials with both the water and oil layers, if present. AC was first evaluated to visualize the standard behavior of this material in water. AC in water, see Figure 5-Part A, was suspended throughout the water with manual mixing. After a few minutes, a portion of the AC settled to the bottom of the tube, while other portions rose to the top and rest on top of the water. Some material clung to the sides of the tubes. AC in the water and mineral oil mixture was thoroughly mixed and allowed to settle over minutes and hours to observe its behavior in this mixed solvent system. About half of the AC was suspended or dissolved in the mineral oil layer on top, see Figure 5-Part B, while the rest of the AC fell to the bottom of the tube as it did with water alone. CP-formulation was evaluated in test tubes in a very similar manner utilizing approximately the same about of material. Figure 5-Part C shows the results after the CP-formulation has been in contact with water for many hours. It appears to have absorbed all the water. It has expanded to the size of the volume of water initially in the test tube. There was about 10 times the mass of water relative to the mass of the CP-formulation. This material appears to absorb water very well. In the water and mineral oil mixture, Figure 5-Part D, the oil formed a layer on top of the water layer. Upon addition of the CP-formulation, it settled to the bottom of the test tube and over a period of hours. During this time, the CP-formulation absorbed all the water with the same characteristics listed above. The mineral oil layer was resting on top, undisturbed. These results utilizes procedure 4, in which an experiment was conducted with AC to compare its characteristics to that of the CP. (Refer to Figure 3) Results showed that activated charcoal does not adsorb water and do adsorb oils. Four trials were run and it can be seen that the AC powder can adsorb about 5 g/g of oil. Quantitative Evaluation of CP Ability to Absorb Various Materials. In the next set of experiments, the goal was to evaluate the various type of substances that could be adsorbed by the CP as well as determine how much grams of substance per grams of CP-formulation could be adsorbed. In Figure 6, one can see the amount of adsorption in grams of substance per grams of CP plotted against time. It can be seen that there was a direct relationship between the adsorbance in g/g as time progressed. Results showed that water adsorbed very well, while other substances adsorbed poorly. The acetone, heptane, 2-propanol, vegetable oil and ethanol were barely adsorbed, while the mineral oil did adsorb to some degree. Once the acetone, heptane, 2-propanol, and ethanol were placed on the CP, the solution would spread out and start evaporating right away. With the CP background also changing, losing weight, it was difficult for an accurate reading to take place. When the oils were added they would rest on top of the patch and there was no change in appearance seen. When the water was added it would remain as a droplet on the CP and it can be seen that it was adsorbing right away. The volatile substances would evaporate too fast for an adsorption reading to take place, so the focus was more on nonpolar oils that do not evaporate at room temperature. There was a weight gain with the 3-PDP and although it was not a lot the patch did adsorb enough of the substance. Figure 6: A graph of the adsorption of various substances versus time. The adsorption in grams of substance per grams of CP plotted against time in seconds. The time was taken in intervals of 5 min from 30 s to 840 s. 0 0.05 0.1 0.15 0.2 0.25 0 100 200 300 400 500 A ds or pt io n in g /g Time in Seconds Charcoal Patch Adsorption