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Analgesic iontophoresis is the administration of analgesic medications via iontophoresis used in the management and treatment of pain. The technique may employ multiple classes of drugs. This activity outlines the indications, action, and contraindications for iontophoresis as a valuable agent in the management of painful conditions. This activity will highlight the mechanism of action, adverse event profile, and other key factors (e.g., off-label uses, dosing, pharmacodynamics, pharmacokinetics, monitoring, relevant interactions) pertinent for members of the healthcare team and patients in the management of patients with acute or chronic pain and related conditions. Objectives: Identify the mechanism of action and administration of iontophoretic analgesia. Describe the adverse effects and contraindications of iontophoretic analgesia. Outline appropriate monitoring and toxicity of iontophoretic analgesia. Review interprofessional team strategies for improving care coordination and communication to advance iontophoretic analgesia and improve outcomes. Access free multiple choice questions on this topic.

In addition to localized, cutaneous adverse effects, patients may experience adverse or even toxicity symptoms stemming from offending therapeutic agents as well. In the context of iontophoretic analgesia, the most used medicines are local anesthetics and fentanyl. With the use of local anesthetics (chiefly lidocaine and lidocaine/epinephrine), acute concerns arise for local adverse reactions and local anesthetic systemic toxicity (LAST). Cardiopulmonary symptoms include heart block, cardiac arrhythmia, respiratory insufficiency and arrest, and cardiac arrest. The central nervous system may similarly experience depression with symptoms such as tinnitus, ataxia, akathisia, seizures, altered levels of consciousness, and coma.[22][25] Management of LAST includes [22][26][27]: Airway management with ventilation, oxygenation Cardiovascular support with epinephrine and antiarrhythmic agents Prophylaxis and suppression of seizures with benzodiazepines and succinylcholine Local anesthetic reduction from intravascular space with lipid-emulsion and bypass With the use of fentanyl, patients may experience cardiopulmonary and CNS depressive symptoms as described before with LAST, however, due to its narrow therapeutic window and often systemic delivery, toxicity symptoms of more acute concern.[28] Although there are no reports of cases of an iontophoretic fentanyl overdose, any compromise to the delivery mechanism may result in the administration of supratherapeutic doses without patient awareness.[15] In cases of a fentanyl overdose, medically appropriate interventions are similar to those of other opioid overdoses, including [28]: Primary survey with airway, breathing, and circulatory support Administration of intravenous (IV), intramuscular (IM), subcutaneous (SQ), or intranasal (NAS) administration of naloxone If indicated, some special circumstances may require complementing the above regimen with activated charcoal, bowel irrigation, and buprenorphine.

Analgesic iontophoresis has numerous applications and offers benefits, including its relative non-invasiveness and bypass of the first-pass metabolism. However, its use in pain relief has been precluded by the more cost-effective nature of injection and transdermal skin patches in addition to safety concerns of unintended overdose.[15] Nonetheless, newer advances may make technology more promising for analgesia in the future. Practitioners prescribing or administering iontophoretic therapies in addition to patients should be acutely aware of indications, realistic therapy goals, and the benefits and risks that accompany the intervention, and consult with a pharmacist to ensure appropriate dosing and the absence of drug interactions. Patients and practitioners should moreover be adequately informed of all clinically germane aspects of the procedure to ensure the correct use and proper administration. Lastly, all of the interprofessional team involved (e.g., physicians, nurses, therapists, pharmacists, patients) should be aware of adverse symptoms and potential signs of toxicity and hypersensitivity and adequately monitor for these signs, as discussed before, to mitigate any adverse outcomes promptly. Pharmacists review medications for indications, dosage, and interactions. Nurses monitor patients, provide education, and report responses and issues to the team. [Level 5]