List of Excipients in Branded Drug SKYLA

Company	Tradename	Ingredient	NDC	Excipient	Potential Generic Entry
Bayer HealthCare Pharmaceuticals Inc	SKYLA	levonorgestrel	50419-422	BARIUM SULFATE
Bayer HealthCare Pharmaceuticals Inc	SKYLA	levonorgestrel	50419-422	DIMETHICONE

Skyla Excipient Strategy and Commercial Opportunities: Pharmaceutical, Device, and Patent Analysis

Last updated: August 7, 2026

Skyla is a levonorgestrel-releasing intrauterine system rather than a conventional tablet, capsule, or injectable drug. Its commercial differentiation depends on controlled drug release from a silicone reservoir, long-term biocompatibility, radiopacity, insertion performance, and reliable uterine delivery. The most attractive excipient opportunities are therefore concentrated in silicone elastomer systems, membrane engineering, device-grade polymers, radiopaque additives, manufacturing controls, and alternative intrauterine delivery platforms.

What is Skyla and how does its formulation work?

Skyla is Bayer’s 13.5 mg levonorgestrel intrauterine system approved by the FDA in 2013 for prevention of pregnancy for up to three years. It is marketed for women, including those who have not previously given birth. The system releases levonorgestrel locally in the uterus and has a reported initial release rate of approximately 14 micrograms per day, declining over time. [1]

Skyla is a drug-device combination product with a polymeric reservoir. Its formulation has four functional components:

Component	Function in Skyla	Commercial relevance
Levonorgestrel	Active pharmaceutical ingredient	Controls contraceptive effect and dose loading
Silicone elastomer	Holds levonorgestrel and forms the drug reservoir	Controls drug diffusion and long-term release
Silicone membrane	Regulates release from the reservoir	Determines release-rate profile and stability
Polyethylene T-body	Provides structural support and uterine positioning	Affects insertion, retention, and device dimensions
Barium sulfate	Makes the device radiopaque	Supports imaging and clinical localization
Polypropylene strings	Permit device removal	Affect handling, visibility, and patient comfort

The silicone elastomer contains colloidal silica, which reinforces the elastomer and supports mechanical integrity. The polyethylene body contains barium sulfate to permit visualization by X-ray or other imaging methods. [1]

Skyla does not rely on a conventional aqueous excipient system. Its excipient strategy is a material-science strategy in which the inactive components determine the rate, duration, safety, and manufacturability of levonorgestrel delivery.

What excipients and device materials protect Skyla’s release profile?

The principal release-controlling materials are silicone elastomer and the surrounding silicone membrane. Levonorgestrel is dispersed in the elastomeric reservoir. The membrane creates a diffusion barrier that controls the movement of the drug into the uterine environment.

Silicone elastomer and colloidal silica

Silicone elastomers are useful for long-term implantable and intrauterine delivery because they are chemically stable, flexible, and relatively permeable to steroid molecules. Colloidal silica reinforces the silicone matrix and improves dimensional stability. Changes in silica loading, particle size, surface treatment, or dispersion can alter:

• Tensile strength
• Drug diffusion pathways
• Reservoir integrity
• Manufacturing consistency
• Extractables and leachables
• Long-term release kinetics

A competing product cannot assume that a different medical-grade silicone will produce an equivalent release profile. The silicone grade, cure chemistry, crosslink density, filler level, drug loading, and processing temperature can all affect performance.

Silicone membrane

The membrane is the most commercially important excipient-like component because it can control the release curve without changing the total levonorgestrel dose. Key variables include:

• Membrane thickness
• Silicone composition
• Permeability
• Cure conditions
• Surface area
• Adhesion to the reservoir
• Manufacturing tolerances

For a generic or follow-on product, membrane composition and dimensions are potential sources of both technical differentiation and intellectual-property risk.

Polyethylene body and barium sulfate

The polyethylene T-body provides structural support. Barium sulfate increases radiopacity, allowing clinicians to locate the device during imaging. The body must balance rigidity with flexibility. Excessive rigidity can increase insertion or perforation concerns, while insufficient rigidity may impair deployment and retention.

Barium sulfate loading can affect:

• Radiographic visibility
• Polymer density
• Mechanical strength
• Molding behavior
• Surface finish
• Device dimensions

Barium sulfate is a mature, widely used radiopaque additive. Its commercial value lies less in exclusivity and more in validated medical-device grades, supply reliability, low extractables, and compatibility with polyethylene processing.

What commercial opportunities exist for Skyla excipient suppliers?

The highest-value opportunities are not commodity excipient sales. They are qualified materials, process packages, and analytical services that reduce regulatory and manufacturing risk.

Medical-grade silicone systems

Suppliers can develop or qualify silicone elastomer systems optimized for steroid-loaded intrauterine reservoirs. A differentiated offering could include:

• Controlled permeability
• Low extractables and leachables
• Consistent colloidal silica dispersion
• Lower-temperature curing
• Improved drug homogeneity
• Compatibility with automated molding
• Documented biocompatibility and sterilization performance

A supplier with a validated formulation and change-control history can create switching costs even where the underlying silicone chemistry is not patent-protected.

Membrane manufacturing

Membrane production is a stronger opportunity than supply of generic silicone. Contract manufacturers can offer:

• Thin-wall silicone extrusion
• Precision coating
• Dimensional inspection
• Inline thickness measurement
• Release-rate testing
• Laser or vision-based defect detection

Because a small change in membrane thickness may affect the release curve over several years, quality systems and process capability are central commercial assets.

Radiopaque polymer compounds

Pre-compounded polyethylene containing barium sulfate can simplify device manufacturing. A supplier may differentiate through:

• Particle dispersion
• Radiopacity at lower filler loading
• Mold-flow performance
• Reduced brittleness
• Consistent color and surface quality
• ISO 10993 documentation

The opportunity is strongest for manufacturers seeking a validated, ready-to-process resin rather than a raw additive.

Extractables, leachables, and stability services

Long-acting intrauterine systems require extended stability programs. Contract laboratories can support:

• Silicone oligomer analysis
• Barium and elemental impurity testing
• Residual catalyst analysis
• Levonorgestrel degradation profiling
• Drug release testing
• Accelerated aging
• Package interaction studies
• In vitro release-to-clinical correlation

These services are commercially valuable because the product has a three-year labeled duration and a permanent or semi-permanent implantation period.

How does Skyla compare with Mirena and Kyleena?

Skyla, Kyleena, and Mirena are all Bayer levonorgestrel-releasing intrauterine systems, but they use different drug loads, dimensions, release profiles, and labeled durations.

Product	Levonorgestrel content	Labeled duration for contraception	Approximate initial release	Key commercial position
Skyla	13.5 mg	3 years	14 mcg/day	Lower-dose, smaller hormonal IUS
Kyleena	19.5 mg	5 years	17.5 mcg/day	Intermediate-dose IUS
Mirena	52 mg	Up to 8 years for contraception	Approximately 20 mcg/day initially	Higher-dose, longer-duration IUS

Mirena also has FDA-approved indications for treatment of heavy menstrual bleeding for up to five years, while Skyla is approved for contraception. Kyleena is primarily positioned as a contraceptive product. [1-3]

Excipient strategy comparison

The products share a general platform based on levonorgestrel, silicone, polyethylene, barium sulfate, and removal strings. The commercial differentiation is achieved through:

• Drug-reservoir loading
• Device size
• Reservoir and membrane configuration
• Release-rate design
• Duration
• Indications
• Insertion system
• Clinical data

This platform approach creates manufacturing efficiencies for Bayer but also increases the importance of formulation and device-family patent analysis for competitors.

When does Skyla lose exclusivity?

Skyla’s regulatory exclusivity is separate from patent protection.

Protection category	Skyla status
FDA approval	Approved February 26, 2013
New chemical entity exclusivity	Expired in 2018
Orphan exclusivity	Not applicable
Pediatric exclusivity	No current product-level extension identified in the core FDA approval record
Patent protection	Must be assessed by patent family, claim scope, terminal disclaimers, and Orange Book status
Generic competition	No FDA-approved interchangeable generic IUS equivalent to Skyla has been established as a conventional ANDA product

The five-year new chemical entity period for levonorgestrel did not provide meaningful protection against later competition because levonorgestrel had long been approved. Skyla’s commercial protection has therefore depended primarily on device design, formulation know-how, clinical evidence, manufacturing capability, and any applicable patent claims.

What is the Orange Book status of Skyla?

Skyla is approved under NDA 203159. The product is a combination of a drug constituent and a delivery device. The FDA Orange Book remains relevant for identifying listed patents and regulatory exclusivity, but an intrauterine system presents a more complex pathway than a conventional oral drug.

A potential competitor must evaluate:

1. Whether the reference product has listed patents.
2. Whether an ANDA is legally and technically appropriate.
3. Whether a 505(b)(2) application is more suitable.
4. Whether the proposed product is sufficiently similar in device design and release profile.
5. Whether clinical or human-factors data are required.
6. Whether the applicant can demonstrate bioequivalence for a locally acting, long-duration product.

A Paragraph IV certification could challenge an unexpired listed patent. The absence of a conventional generic pathway does not eliminate patent risk. Device claims, manufacturing claims, and formulation claims can remain relevant even when drug-substance exclusivity has expired.

What patent claims are most important for Skyla?

The most relevant claim categories are likely to include:

• Intrauterine systems containing levonorgestrel
• Silicone drug reservoirs
• Membrane-controlled release
• T-shaped intrauterine devices
• Specific drug-loading ranges
• Release rates over defined time periods
• Device dimensions
• Insertion systems
• Manufacturing methods
• Combinations of reservoir, membrane, and support body

Patent analysis should separate claims directed to the drug product from claims directed to the device. A patent that claims a specific levonorgestrel release profile may create a different risk from a patent claiming a structural arrangement or manufacturing step.

Patent-strength assessment

Factor	Assessment for Skyla
Active ingredient novelty	Weak, because levonorgestrel is an established compound
Delivery-system differentiation	Stronger, because long-term uterine delivery requires specialized design
Formulation complexity	Moderate to strong, based on silicone reservoir and membrane performance
Manufacturing barriers	Strong, due to precision molding, loading, curing, and release testing
Clinical substitution risk	Moderate, because local delivery and device performance matter
Biosimilar relevance	None in the conventional FDA sense
Generic development complexity	High relative to oral levonorgestrel products

Which companies are challenging Skyla?

Skyla has not produced a competitive landscape comparable to oral drugs facing multiple ANDA filers. The main competitive pressure comes from other long-acting reversible contraceptives, not from direct generic Skyla substitutes.

Relevant competitors include:

• Bayer’s Mirena and Kyleena
• Organon’s Nexplanon implant
• CooperSurgical’s Paragard copper IUD
• AbbVie’s Liletta, marketed through Medicines360
• Oral contraceptives and progestin-only products
• Emerging long-acting contraceptive implants and intrauterine technologies

Liletta is the closest branded comparator in the hormonal IUS segment, although its dose, device configuration, indications, and duration differ from Skyla. Paragard competes for the same intrauterine placement decision but uses copper rather than levonorgestrel.

What litigation and settlement risks affect Skyla?

Public litigation risk should be reviewed across four categories:

1. Patent-infringement litigation involving the intrauterine device or release system.
2. Product-liability litigation involving perforation, expulsion, migration, or pregnancy.
3. Regulatory disputes involving generic or follow-on submissions.
4. Commercial disputes involving manufacturing, supply, or licensing.

No biosimilar litigation framework applies because Skyla is not a biologic. A potential competitor would more likely face patent litigation under the Hatch-Waxman framework, a 505(b)(2) dispute, or device-related patent litigation.

Settlement agreements could delay launch if a challenger reaches an agreement with Bayer. Such agreements would require review of launch dates, authorized-generic provisions, licensing rights, manufacturing restrictions, and patent licenses. No commercial settlement should be assumed without a filed court document, FTC disclosure, or company announcement.

What regulatory barriers exist for a Skyla follow-on product?

The principal regulatory barrier is demonstrating equivalent long-term local delivery. A follow-on applicant may need to address:

• Levonorgestrel content uniformity
• In vitro release over the full labeled duration
• Device dimensions and insertion behavior
• Mechanical strength and flexibility
• Radiopacity
• Sterility
• Biocompatibility
• Extractables and leachables
• Human factors
• Clinical performance
• Pregnancy prevention efficacy
• Expulsion and perforation rates

A conventional pharmacokinetic bioequivalence study may not adequately establish equivalence for a uterine-reservoir product. The regulatory strategy may therefore require a combination of in vitro release testing, comparative device characterization, pharmacokinetic data, and clinical evidence.

What generic launch scenarios exist for Skyla?

Scenario 1: Direct generic or follow-on IUS

This would require a device with comparable dimensions, levonorgestrel loading, release profile, and clinical performance. It has the highest development cost but the strongest potential substitution.

Scenario 2: 505(b)(2) product

A company could develop a modified levonorgestrel intrauterine system with different dimensions, dose, duration, or insertion characteristics. This approach could support product differentiation but would likely require additional clinical data and would not eliminate patent exposure.

Scenario 3: Alternative long-acting contraceptive

A company could avoid direct Skyla substitution by developing a different hormonal IUS, implant, or nonhormonal device. This shifts the competition from pharmaceutical equivalence to clinical outcomes, patient preference, insertion experience, and duration.

Scenario 4: Manufacturing or licensing partnership

A device manufacturer could license a reservoir, membrane, insertion system, or manufacturing process to an established pharmaceutical company. This strategy reduces commercialization risk and may create value without competing directly against Bayer.

What revenue exposure does Skyla create?

Bayer does not generally report Skyla revenue as a standalone public segment. Its financial exposure is included within the Pharmaceuticals business and women’s healthcare portfolio. Revenue analysis therefore requires indirect estimates based on:

• Prescription and procedure volumes
• Net price
• Market share within hormonal IUS products
• Duration of use
• Regional availability
• Reimbursement
• Competition from Kyleena, Mirena, and Liletta

Skyla’s lower dose and shorter duration can reduce lifetime revenue per patient relative to Mirena or Kyleena. Its smaller size and lower hormonal exposure can support a distinct patient segment, preserving commercial value even when longer-duration products have a lower annualized cost.

How can an excipient supplier build a defensible Skyla opportunity?

A defensible strategy should focus on qualified performance rather than undifferentiated raw materials.

1. Develop a medical-grade silicone system with validated levonorgestrel compatibility.
2. Establish membrane thickness and permeability specifications linked to release performance.
3. Supply barium sulfate-filled polyethylene with documented radiopacity and mechanical properties.
4. Build extractables, leachables, and aging datasets.
5. Offer process validation for reservoir loading, curing, membrane application, and dimensional inspection.
6. Protect improvements through patents covering composition, device architecture, processing, or release control.
7. Use regulatory documentation and change-control support to create customer retention.
8. Pursue licensing with established contraceptive or women’s-healthcare companies.

The strongest commercial position is an integrated material-and-process package that reduces the customer’s technical and regulatory burden.

Key Takeaways

• Skyla is a drug-device combination product built around levonorgestrel, silicone elastomer, a silicone membrane, polyethylene, barium sulfate, and polypropylene removal strings.
• Its commercial performance depends more on controlled diffusion and device engineering than on conventional pharmaceutical excipients.
• Silicone reservoir and membrane technology are the most important formulation-related components.
• Barium sulfate and polyethylene are mature materials, but qualified medical-device grades can still create supplier value.
• Skyla’s new chemical entity exclusivity expired in 2018; remaining protection depends on patents, regulatory barriers, manufacturing know-how, and clinical differentiation.
• No biosimilar pathway applies.
• Direct generic competition is difficult because equivalence must address local uterine delivery, device performance, long-term release, and insertion.
• The best commercial opportunities are validated silicone systems, membrane manufacturing, radiopaque polymer compounds, release testing, and licensing.
• Mirena, Kyleena, Liletta, Nexplanon, and Paragard are the principal competitive benchmarks.
• Product-level Skyla revenue is not separately disclosed by Bayer.

FAQs

Can Skyla excipients be replaced without changing the product’s regulatory status?

No. Replacing silicone, membrane materials, polyethylene, barium sulfate, or other device materials can change release, biocompatibility, mechanical performance, or extractables. A material change would require documented comparability and could require regulatory review.

Is Skyla eligible for a traditional generic drug application?

A conventional ANDA pathway may be difficult because Skyla combines a locally acting drug with a long-term intrauterine device. The regulatory route would depend on the proposed product’s similarity, device characteristics, release profile, and applicable FDA requirements.

Are Skyla’s excipients patentable?

The raw materials are generally established materials. Patentability is stronger for specific compositions, reservoir configurations, membrane structures, manufacturing methods, release profiles, and combinations of materials that produce a defined performance result.

Does Skyla have biosimilar competition?

No. Biosimilar law applies to biological products. Skyla contains the synthetic steroid levonorgestrel and is regulated as a drug-device combination product.

Which component creates the greatest manufacturing barrier?

The silicone drug reservoir and membrane system create the greatest barrier because they must deliver a reproducible levonorgestrel release profile for three years while maintaining dimensional integrity, sterility, and biocompatibility.

References

1. U.S. Food and Drug Administration. (2023). Skyla: Levonorgestrel-releasing intrauterine system prescribing information. Bayer HealthCare Pharmaceuticals Inc.

2. U.S. Food and Drug Administration. (2013). Skyla approval letter and regulatory review materials. Center for Drug Evaluation and Research, NDA 203159.

3. U.S. Food and Drug Administration. (2023). Mirena: Levonorgestrel-releasing intrauterine system prescribing information. Bayer HealthCare Pharmaceuticals Inc.

4. U.S. Food and Drug Administration. (2023). Kyleena: Levonorgestrel-releasing intrauterine system prescribing information. Bayer HealthCare Pharmaceuticals Inc.

5. U.S. Food and Drug Administration. (2024). Approved drug products with therapeutic equivalence evaluations. Center for Drug Evaluation and Research.

6. U.S. Food and Drug Administration. (2024). Orange Book: Approved drug products with therapeutic equivalence evaluations. Center for Drug Evaluation and Research.