What Do GLP-1 Patches Do? UK Guide to Transdermal GLP-1 Therapy

GLP-1 patches represent an emerging transdermal delivery system designed to administer glucagon-like peptide-1 receptor agonists through the skin, potentially offering an alternative to traditional injections for type 2 diabetes and weight management. These patches aim to deliver medication continuously, maintaining steady drug levels whilst avoiding the need for weekly or daily injections. However, it is crucial to understand that no GLP-1 patches are currently licensed by the MHRA in the UK. All available GLP-1 therapy relies on established injectable formulations such as semaglutide, dulaglutide, and liraglutide, which have extensive clinical evidence supporting their use.

What Are GLP-1 Patches and How Do They Work?

GLP-1 patches represent an emerging transdermal delivery system for glucagon-like peptide-1 (GLP-1) receptor agonists, medications traditionally administered via subcutaneous injection. These patches are designed to deliver GLP-1 analogues through the skin and into the bloodstream, offering a potential alternative to weekly or daily injections currently used for type 2 diabetes and weight management.

GLP-1 is a naturally occurring incretin hormone produced in the intestine that plays a crucial role in glucose regulation. When GLP-1 receptor agonists are delivered—whether by injection or potentially through a patch—they mimic this natural hormone by binding to GLP-1 receptors throughout the body. This binding triggers several important physiological responses: enhanced insulin secretion from pancreatic beta cells in response to elevated blood glucose, suppression of glucagon release (which normally raises blood sugar), delayed gastric emptying (slowing food passage from stomach to intestine), and increased satiety through effects on appetite centres in the brain.

The transdermal patch technology aims to maintain steady drug levels in the bloodstream through continuous absorption across the skin barrier. This differs from injections, which create peak-and-trough concentration patterns. The patch typically contains the active GLP-1 analogue within a reservoir or matrix system, alongside penetration enhancers that facilitate drug passage through the stratum corneum (the skin's outer protective layer). However, conventional patches face significant challenges with peptide delivery due to the large molecular size of GLP-1 analogues, which is why many research approaches focus on microneedle technologies or advanced penetration enhancers.

It is important to note that no GLP-1 patches are currently licensed by the MHRA in the UK. All current GLP-1 therapy relies on established injectable formulations such as semaglutide (Ozempic®, Wegovy®), dulaglutide (Trulicity®), and liraglutide (Victoza®, Saxenda®), which have extensive clinical evidence supporting their efficacy and safety.

What Conditions Do GLP-1 Patches Treat?

GLP-1 patches, like their injectable counterparts, are being developed primarily for two interconnected therapeutic areas: type 2 diabetes mellitus and obesity management. The underlying mechanisms of GLP-1 receptor agonism make these medications particularly suited to addressing both conditions simultaneously.

For type 2 diabetes, GLP-1 therapy works by improving glycaemic control through multiple pathways. By enhancing glucose-dependent insulin secretion, these medications help lower blood glucose levels particularly after meals, whilst the suppression of inappropriate glucagon release prevents excessive hepatic glucose production. Importantly, because GLP-1 receptor agonists work in a glucose-dependent manner, they generally carry a lower risk of hypoglycaemia compared to some other diabetes medications. However, when combined with insulin or sulphonylureas, the risk of hypoglycaemia increases significantly and dose adjustments of these agents may be needed. NICE guidance (NG28) recommends GLP-1 receptor agonists as treatment options for adults with type 2 diabetes when metformin and other oral therapies have not achieved adequate glycaemic control, or when there are specific clinical considerations such as significant obesity or high cardiovascular risk.

Weight management represents the second major indication. GLP-1 receptor agonists promote weight loss through reduced appetite, increased feelings of fullness, and delayed gastric emptying. Clinical trials with injectable GLP-1 medications have demonstrated substantial weight reduction. NICE technology appraisals TA875 (semaglutide 2.4mg/Wegovy®) and TA664 (liraglutide 3mg/Saxenda®) support their use specifically for weight management in adults within specialist weight management services. Eligibility typically requires a BMI ≥35 kg/m² (or ≥32.5 kg/m² in people from certain ethnic groups), or a BMI ≥30 kg/m² with weight-related comorbidities, alongside engagement with lifestyle modification programmes. Treatment is time-limited and subject to response criteria.

Emerging evidence also suggests potential cardiovascular benefits, with some injectable GLP-1 receptor agonists demonstrating reduced risk of major adverse cardiovascular events in people with established cardiovascular disease. Any future GLP-1 patch formulations would need to demonstrate similar therapeutic benefits across these indications through rigorous clinical trials before receiving regulatory approval from the MHRA and EMA.

How Effective Are GLP-1 Patches Compared to Injections?

Direct comparative effectiveness data between GLP-1 patches and established injectable formulations remains limited, as transdermal GLP-1 delivery systems are still largely in developmental or early clinical trial phases. However, several important considerations influence the potential effectiveness of patch-based delivery versus injections.

Bioavailability—the proportion of drug that reaches systemic circulation—represents a critical challenge for transdermal GLP-1 delivery. Injectable GLP-1 receptor agonists achieve high bioavailability through subcutaneous administration, with the medication directly entering the bloodstream. In contrast, transdermal delivery must overcome the skin's natural barrier function, which evolved specifically to prevent external substances from entering the body. GLP-1 analogues are relatively large peptide molecules, making skin penetration particularly challenging. Current research focuses on enhancing transdermal absorption through various technologies including microneedle patches, chemical penetration enhancers, and modified drug formulations.

Clinical outcomes with established injectable GLP-1 receptor agonists are well-documented. Medications such as semaglutide and dulaglutide consistently demonstrate HbA1c reductions of 1.0-1.5% (11-16 mmol/mol) in people with type 2 diabetes. Weight loss outcomes vary by agent and dose: high-dose semaglutide (2.4mg/Wegovy®) has shown mean weight reductions of approximately 15% in the STEP clinical trials, while liraglutide (3mg/Saxenda®) typically achieves 5-8% weight loss. For any GLP-1 patch to gain clinical acceptance, it would need to demonstrate non-inferior efficacy to these established benchmarks through head-to-head comparative trials.

Patient adherence may theoretically improve with patch-based delivery, as some individuals find regular injections burdensome or anxiety-provoking. However, patches present their own adherence challenges, including skin irritation, adhesion problems, and the need for regular application site rotation. Real-world effectiveness ultimately depends not just on pharmacological potency but on consistent, correct usage.

Until robust phase III clinical trial data becomes available comparing transdermal and injectable GLP-1 formulations directly, healthcare professionals must rely on established injectable therapies with proven efficacy and safety profiles for managing type 2 diabetes and obesity.

Potential Side Effects and Safety Considerations

The side effect profile of any GLP-1 patch would likely reflect both the systemic effects of GLP-1 receptor agonism (common to all delivery methods) and local effects specific to transdermal administration. Understanding both categories is essential for informed decision-making and patient safety.

Gastrointestinal side effects represent the most common adverse reactions with GLP-1 receptor agonists, regardless of delivery method. These include:

• Nausea (affecting 20-40% of patients initially)

• Vomiting

• Diarrhoea

• Constipation

• Abdominal discomfort

These effects typically arise from delayed gastric emptying and direct effects on the gastrointestinal tract. They are usually most pronounced during treatment initiation and dose escalation, often improving over several weeks as tolerance develops. Gradual dose titration, as recommended in current prescribing guidance, helps minimise these symptoms.

Serious but rare adverse effects associated with injectable GLP-1 receptor agonists include acute pancreatitis, gallbladder disease (cholecystitis and cholelithiasis), and potential thyroid effects. Rodent studies have shown C-cell tumours with GLP-1 receptor agonists, but the relevance to humans is unknown. UK prescribing information includes this as a warning/precaution rather than a contraindication, advising caution in patients with personal or family history of medullary thyroid carcinoma or multiple endocrine neoplasia syndrome type 2.

People with diabetes using GLP-1 receptor agonists should be aware that rapid improvements in blood glucose control may be associated with temporary worsening of diabetic retinopathy, particularly with semaglutide. Appropriate ophthalmic monitoring is advised for those with pre-existing retinopathy. When GLP-1 receptor agonists are used with insulin or sulphonylureas, the risk of hypoglycaemia increases, and dose reductions of these medications may be necessary.

Transdermal-specific considerations for patches would include:

• Local skin reactions (erythema, itching, irritation at application site)

• Contact dermatitis from adhesive components or penetration enhancers

• Skin integrity concerns requiring regular site rotation

Patient safety advice for anyone using GLP-1 therapy includes:

• Report persistent severe abdominal pain (potential pancreatitis)

• Monitor for signs of gallbladder problems (right upper quadrant pain, particularly after meals)

• Maintain adequate hydration, especially if experiencing vomiting or diarrhoea

• Contact your GP if side effects are severe, persistent, or concerning

• Report suspected side effects via the MHRA Yellow Card scheme (yellowcard.mhra.gov.uk)

Regarding pregnancy and breastfeeding, advice varies by product. Semaglutide 2.4mg (Wegovy®) is contraindicated in pregnancy, while other GLP-1 receptor agonists are generally not recommended. Women using semaglutide should discontinue treatment at least 2 months before a planned pregnancy. Women of childbearing potential should use effective contraception during treatment with GLP-1 receptor agonists.

Availability and Prescribing in the UK

Currently, GLP-1 patches are not licensed or available for prescribing in the UK. The Medicines and Healthcare products Regulatory Agency (MHRA) has not approved any transdermal GLP-1 formulations for clinical use. All currently available GLP-1 receptor agonist therapy in the UK is administered via subcutaneous injection, either as daily or weekly formulations.

Licensed injectable GLP-1 medications available through the NHS include:

• Semaglutide (Ozempic® for diabetes; Wegovy® for weight management)

• Dulaglutide (Trulicity®)

• Liraglutide (Victoza® for diabetes; Saxenda® for weight management)

• Exenatide (Byetta®, Bydureon®) - though availability may vary by region

Prescribing of these medications follows NICE guidance with different pathways depending on indication. For type 2 diabetes (NICE NG28), GLP-1 receptor agonists are generally considered after metformin-based therapy has proven insufficient, and can be initiated in primary care according to local formularies and prescribing arrangements. For weight management, NICE technology appraisals TA875 (semaglutide/Wegovy®) and TA664 (liraglutide/Saxenda®) specify that treatment must be initiated within specialist weight management services, with specific BMI thresholds and time-limited treatment periods.

Supply challenges have affected GLP-1 medications in recent years, with significant shortages of semaglutide products driven by increased global demand. NHS England and the Department of Health and Social Care have issued guidance prioritising supply for patients with type 2 diabetes and those already established on treatment. These supply constraints have limited new initiations for weight management indications.

Should GLP-1 patches complete clinical development and receive regulatory approval in future, they would undergo health technology assessment by NICE to determine cost-effectiveness and appropriate positioning within NHS treatment pathways. Factors influencing adoption would include comparative efficacy, safety profile, patient acceptability, and overall cost relative to established injectable formulations.

Patients interested in GLP-1 therapy should discuss options with their GP or specialist diabetes/obesity service. Private prescribing is available but costly, and patients should ensure any private provider is appropriately regulated. Purchasing medications from unregulated online sources carries significant safety risks, including counterfeit products and absence of medical supervision. All GLP-1 therapy requires ongoing medical monitoring to assess response, manage side effects, and ensure appropriate continuation or discontinuation based on individual outcomes.

Frequently Asked Questions