Adhesives present a unique drug delivery option, providing steady-state dosage without the fluctuating plasma concentration and adherence challenges often found in oral and injectable formulations. Adhesives also present a unique option for localized drug delivery; a therapeutic is provided to a specific part of the body, but does not result in drug absorption to the systemic circulation. With customizable release profiles and enhanced bioavailability, these systems can help sponsors differentiate their products and more effectively meet patient needs.
What Are Adhesive-Based Drug Delivery Systems?
Adhesive drug delivery systems are designed to administer APIs through the skin or mucosal membranes, enabling either a localized or a controlled, continuous release tailored to patient needs. Unlike conventional drug delivery methods that often result in whole-body systemic circulation with fluctuating plasma concentrations, these systems maintain either a targeted body site drug therapy, avoiding a body-wide delivery, or these systems maintain consistent systemic levels over time.
Compared to traditional oral tablets or injectables, these adhesive solutions offer several key advantages:
- Tailored Release: Ensures a steady-state concentration in the blood for optimal efficacy or alternatively, ensures a targeted local drug concentration that avoids systemic blood circulation, resulting in fewer side effects.
- Non-Invasive: Eliminates the need for injections or frequent oral dosing.
- Enhanced Compliance: Simple application methods improve patient adherence.
- Reduced Systemic Side Effects: Avoids gastrointestinal degradation and first-pass metabolism, improving bioavailability. Local delivery avoids side effects associated with systemic delivery.
By optimizing pharmacokinetic profiles, adhesive drug delivery systems provide more predictable and effective treatment outcomes.
How Do Adhesive-Based Drug Delivery Systems Work?
Mechanism of Action
The effectiveness of adhesive-based drug delivery lies in its ability to facilitate the API’s direct absorption into systemic circulation or provide the API’s direct absorption to the targeted tissue.
- Transdermal patches enable drug permeation through the epidermis and dermis before entering capillary networks.
- Mucoadhesive patches and films can be designed to dissolve in the oral cavity, allowing rapid uptake through the buccal mucosa or they may be designed to be non-dissolving so that they may be removed after a specified time.
Both methods bypass the hepatic first-pass effect, enhancing bioavailability and ensuring a more efficient therapeutic response.
- Topical patches enable drug permeation through the epidermis and directly to the targeted tissue, thereby conveying a local drug therapeutic effect while avoiding entering the systemic circulation.
READ MORE: Adhesives and Drug Delivery: How Stick-On Solutions Are Advancing Therapeutics
The Role of Adhesion in Drug Delivery
Adhesive properties are fundamental to these systems, ensuring prolonged contact with the application site for controlled drug diffusion. Formulations must balance strong adhesion for sustained efficacy and ease of removal to prevent skin or mucosal irritation.
Formulation Considerations
The effectiveness of adhesive-based drug delivery systems relies on carefully formulating key components, including adhesion properties, drug solubility, and stability. Adhesive strength is essential for maintaining proper contact with the skin or mucosal surfaces, ensuring consistent and efficient drug absorption over time. The right balance of adhesive strength also provides comfort for patients while keeping the delivery system in place.
Formulations may also include permeation enhancers, such as alcohols or fatty acids, temporarily altering the skin or mucosal barrier to improve drug absorption. These ingredients may boost drug solubility and enhance the penetration of the active ingredient, ensuring more reliable therapeutic outcomes.
By selecting the right components, manufacturers can create adhesive drug delivery systems that offer patients effective, comfortable, and consistent treatment.
Types of Adhesive Drug Delivery Systems
Adhesive-based drug delivery systems can be engineered to accommodate specific therapeutic needs, utilizing different structural designs to regulate pharmacokinetics.
Single-Layer
Single-layer adhesive-based systems have a simple yet effective design where the API is integrated within a single adhesive matrix. These systems allow rapid drug diffusion through the adhesive layer directly into the skin or mucosa, making them ideal for rapid-onset medications.
Multi-Layer
Multi-layer adhesive systems utilize two or more layers to control the drug’s release profile. Each layer serves a specific purpose—enhancing adhesion, controlling drug release, or protecting the active ingredient. These systems are ideal for drugs that must be delivered at controlled rates, offering sustained release over extended time periods and ensuring that therapeutic levels are maintained throughout the intended treatment.
READ MORE: Transdermal Patches: What They Are, How They Work & Why Patients Like Them
Mucoadhesive Systems
Designed to adhere to mucosal tissues (e.g., oral, nasal, vaginal), these systems utilize bioadhesive polymers to prolong retention and maximize localized or systemic drug absorption. Mucoadhesive delivery is particularly beneficial for drugs with poor gastrointestinal stability or those requiring rapid onset.
READ MORE: Everything You Need to Know About Buccal Thin Films
Topical Systems
Designed to adhere to skin or mucosal tissues, these systems utilize the same adhesive or bioadhesive polymers discussed above. These systems maximize localized drug absorption to avoid systemic drug delivery. They are particularly beneficial for drugs exhibiting systemic side effects or those requiring rapid onset at the local tissue site.
Benefits of Adhesive Drug Delivery Systems for Patients
Ease of Use
Adhesive drug delivery systems are straightforward and user-friendly, requiring no special tools or preparation. Patients simply remove the protective plastic layer and apply the adhesive patch or film to the skin or mucosal surface, making them accessible to a broad range of individuals, including those with limited dexterity or mobility.
Continuous Medication Delivery
Unlike traditional dosage forms that may lead to peaks and troughs in drug blood concentration, adhesive systems provide a controlled release, steady-state plasma levels and reduced side effects that are typically associated with fluctuating oral drug exposure.
Non-Invasive and Pain-Free
For patients with needle phobia or those requiring long-term therapy, adhesive systems offer a comfortable, pain-free alternative to injections.
Improved Medication Adherence
By reducing dosing frequency and simplifying drug administration, adhesive systems promote higher adherence rates, leading to better disease management and therapeutic success.
Benefits of Adhesive Drug Delivery Systems for Pharmaceutical Companies
Precision Dosing
Adhesive systems minimize risks associated with under- or overdosing by maintaining controlled and predictable drug release, improving clinical outcomes and regulatory compliance.
Enhanced Bioavailability
Since these systems bypass the gastrointestinal tract and hepatic metabolism, lower doses can achieve therapeutic efficacy, reducing API wastage and optimizing cost efficiency.
Reduced Production Costs
With streamlined manufacturing processes and lower API requirements, adhesive-based formulations offer cost-effective alternatives to injectables and specific oral formulations.
Lifecycle Management & Market Differentiation
Pharmaceutical companies can leverage adhesive drug delivery to extend product lifecycles, reposition existing APIs, and create differentiated formulations with added convenience and compliance benefits.
Higher Patient Adherence
Improved patient compliance translates to better long-term outcomes, higher prescription retention rates, and greater commercial success for pharmaceutical companies.
Development Challenges and Considerations
While adhesive drug delivery systems present numerous advantages, their development requires meticulous planning to overcome inherent challenges.
Drug Stability
APIs must be formulated to withstand potential degradation from environmental exposure. Protective excipients and stabilizers help ensure efficacy throughout the product’s shelf life. Unit-dose packaging of adhesive drug delivery systems prevents environmental exposure as typified for multi-packaged oral dosage forms.
Adhesion and Retention
Formulations must balance strong adhesion with easy removal to avoid skin irritation. Variability in patient skin types, humidity, and physical activity levels necessitates rigorous testing during drug development to optimize adhesive performance.
Limited Absorption Area
The available surface area constrains transdermal and mucosal absorption. To achieve therapeutic goals, careful API selection, permeation enhancement strategies, and potential dose modifications are necessary.
Regulatory Considerations
Sponsors developing adhesive drug delivery systems must comply with strict regulatory requirements to ensure safety, efficacy, and quality. Compliance covers formulation, clinical testing, manufacturing, and labeling.
Pre-Clinical Testing & Safety Studies
Pre-clinical studies are undertaken to determine the safety of the proposed drug delivery system prior to human clinical study, and to assure regulatory authorities that the clinical formulation is safe for human use. Pre-clinical studies include in vitro and animal studies.
Clinical Testing & Bioavailability Studies
Bioavailability studies are essential to confirm that the drug is absorbed through the mucosa or skin at the intended rate and extent. These studies assess systemic exposure and therapeutic effectiveness.
Clinical trials progress through Phases I, II, and III to establish safety and efficacy, while adherence to Good Manufacturing Practices (GMP) ensures quality and consistency in production of the clinical supplies. Regulatory agencies require comprehensive pharmacokinetic and pharmacodynamic data to support approval.
Regulatory Pathways and Approvals
Approval pathways depend on the product type and jurisdiction. In the U.S., sponsors typically submit a New Drug Application (NDA) for novel formulations or an Abbreviated New Drug Application (ANDA) for generics. Regulatory bodies like the FDA and the European Medicines Agency (EMA) review clinical trial data, stability studies, and manufacturing documentation to ensure compliance.
Regulatory submissions must provide robust evidence of drug safety, efficacy, and quality, including detailed assessments of adhesion performance, release kinetics, and degradation profiles.
Labeling and Documentation Requirements
Accurate labeling is critical for proper use and patient safety. Labels must include the approved indication, dosing instructions, application guidelines, contraindications, and safety warnings.
Sponsors must also submit comprehensive documentation proving GMP compliance and long-term stability to demonstrate the product’s reliability over its lifecycle.
Post-Approval Monitoring
Once on the market, adhesive drug delivery systems require ongoing pharmacovigilance to track adverse events and ensure continued safety and efficacy.
Manufacturers must conduct periodic stability testing and evaluate post-market performance data to detect deviations in drug release or adhesion properties. Regulatory agencies may require periodic reporting to confirm sustained compliance.
How to Properly Use Adhesive Delivery Systems: A Patient’s Guide
Proper application and care optimize the effectiveness of adhesive drug delivery systems. Follow these key guidelines to ensure consistent drug absorption.
How to Apply an Adhesive Drug Delivery System
- Clean and dry the application site. Avoid lotions, oils, or powders, as they can interfere with adhesion.
- Carefully peel off the protective liner, avoiding contact with the adhesive.
- For transdermal patches: Apply to a clean, dry, and hair-free skin area,as specified in the product labeling. Press firmly for several seconds to secure adhesion.
- For buccal patches/films: Place against the inner cheek or gum, following product-specific instructions. Hold in place briefly to ensure proper adherence.
What to Do if the System Falls Off or Becomes Loose
If the system detaches prematurely, follow the product’s replacement guidelines. Do not use additional adhesives or tape for transdermal systems, as this may alter drug delivery.
How Often to Change the System
Replacement schedules vary by product. Some systems require daily changes, while others are designed for weekly application. To maintain consistent drug levels, always adhere to the prescribed schedule.
Where to Place the Adhesive
For topical patches or transdermal systems, apply the patch to clean, dry skin free from cuts or irritation. Common application areas for transdermal systems include the upper arm, back, or chest, depending on the product’s labeling. Rotate the application sites to prevent skin irritation and ensure consistent absorption. Application areas for topical systems are dependent upon each product’s labeling and the specific body site in need of drug therapy.
For buccal patches/films, place them against the inside of your cheek or gum. To prevent discomfort or improper adhesion, avoid placing them over cuts, sores, or irritated areas in the mouth.
Conclusion
Adhesive delivery systems offer a convenient and non-invasive alternative to oral medications or injections. If you’re considering an adhesive system, working with a knowledgeable provider specializing in these products, like ARx, can help ensure successful treatment and optimized results.
ARx is a patient-friendly, novel drug delivery partner. We specialize in oral thin film, buccal film, topical and transdermal patch strategies — all backed by tailored, full-scale development services. Contact us today to find the right delivery system for your API.