Patches That Heal: Transdermal Systems for Mental Illness
FDA approves first transdermal patch for schizophrenia.
Posted Nov 20, 2019
Patients and prescribers alike are familiar with the vast array of psychiatric medicines available to treat mental illnesses. They are often less aware that certain psychotropics can be delivered via a “patch” through the top layers of the skin.
The recent decision by the U.S. Food and Drug Administration (FDA) to approve the first transdermal therapeutic system to treat adults with schizophrenia (Secuado) stoked renewed interest in psychopharmacology via patch.
There are more than 20 transdermal therapeutic systems approved by the FDA for use in the United States. (See table below.) Often, people tend to associate these systems with uses such as birth control, nicotine replacement therapy, or motion sickness prevention. Increasingly, transdermal delivery offers a promising alternative route for drug administration in behavioral health. As such, providers, patients and members of their support system should have a basic understanding of the common patch medicines for mental illness currently on the market, as well as their benefits and limitations.
Some of the transdermal drugs that act on the central nervous system include cholinesterase inhibitors for dementia; methylphenidate for attention deficit hyperactivity disorder (ADHD); monoamine oxidase inhibitors (MAOIs) for depression; dopamine agonists for Parkinson's disease and restless leg syndrome; and clonidine for ADHD and impulse control disorders.
Transdermal drug delivery offers several potential benefits:
- Ease of use and convenience for patients. Patches may be applied to the skin once a day or even once a week, which dramatically simplifies the treatment regimen for those taking multiple doses of oral preparations.
- Enhanced compliance. Patches are noninvasive and can be self-administered. They provide a visual reminder for patients and caregivers that treatment has been dispensed. They also provide an alternative for patients who have difficulty swallowing.
- Rate-controlled dosage delivery. By controlling the dosage release, there is no metabolism through the gastrointestinal system, preventing fluctuating plasma concentrations that are often seen with orally administered medicines.
Limitations and Safety Concerns
These systems do have some limitations and safety concerns, including:
- Skin irritation. Contact dermatitis is the most common type of reaction seen at the site of patch application. It is most often the result of exposure to the agent being administered or to the structural components of the patch itself. It presents as a sharply demarcated rash that conforms to the area where the patch was applied. In general, these cutaneous reactions can be managed by rotating the application site, placing the patch on less sensitive areas of the skin (e.g., upper arm or hip) or reducing the duration of patch adhesion.
- Effective patch adhesion. Absorption of the medicine can be compromised if the patch does not remain in contact with the skin. Patch adhesion can be especially difficult during the summer or for those engaged in swimming or other strenuous physical activities that cause excessive sweating.
- Molecular delivery challenges. Only some molecules can successfully be delivered through the skin. Traditional patch systems are limited to small, relatively lipophilic molecules that can pass through the outer layers of the skin. Most psychotropics are poorly suited for transdermal delivery because of their large size and molecular complexity; only a narrow range of molecules can be delivered through the skin using available technologies.
- Slower onset. Transdermal therapeutic systems can take longer to become active than oral or intravenous forms of similar medications. With any medication, however, it’s important to allow ample time to evaluate the effectiveness.
The emergence of transdermal delivery for medicines with psychotropic properties will facilitate the ability to customize therapy for patients by altering the duration of therapy, minimizing variable metabolism in the gut and minimizing the potential for drug-drug interactions. It will also decrease the risk for gastrointestinal tract irritation.
With its approval of Secuado, the FDA has expanded treatment options for schizophrenia in a new and exciting direction. Future advances in delivery technologies could expand the number and broaden the clinical use of available drugs in the psychiatric arena, allowing clinicians to overcome limitations of many oral medicines, the pain and inconvenience of injections, and the limited controlled-release options for both.