Cosette Pharmaceuticals’ planned $430 million acquisition of Australia-based Mayne Pharma was positioned to strengthen its position in women’s health and dermatology. The proposed deal announced last February 2025 would have covered 12 patent-protected products, including Nextstellis®, Annovera®, Bijuva®, Imvexxy®, and Vyleesi®, along with FDA-approved manufacturing sites in the U.S. and Australia. Through this acquisition, Cosette was aiming to rapidly scale its specialty portfolio and global reach.
However, on June 4, 2025, Cosette Pharmaceuticals confirmed plans to terminate its takeover bid, citing a “material adverse change” in Mayne’s financial performance and a warning letter from the FDA over promotional claims about its contraceptive, Nextstellis. Mayne has indicated its intent to contest the termination, maintaining there has been no material change.
The planned deal aligns with broader momentum in the women’s health market, which was valued at $43.15 billion in 2023 and is projected to grow to $65.23 billion by 2031. With increasing attention on gender-specific care and personalized treatment options, the proposed acquisition reflected Cosette’s strategic interest in addressing rising demand for reproductive, menopausal, and other women’s health therapies while enhancing its capacity to compete in a rapidly growing market.
What’s at stake in Women’s Health M&A
According to a recent study, only 5% of global healthcare R&D has been dedicated to women’s health, leaving critical gaps in areas such as reproductive health, menopause care, and chronic conditions that disproportionately affect women.
Mergers and acquisitions in women’s health are accelerating as demand rises for specialized care in areas long underfunded and underserved. Once seen as niche, the sector is now drawing major investment interest, with the World Economic Forum projecting a $1 trillion global economic opportunity by 2040.
The trend has been especially active in pharmaceuticals and specialty care, where companies are acquiring complementary assets to deepen their capabilities and tap into fast-growing market segments. Private equity has already funneled over $80 billion into women’s health deals over the past four years, with strong median returns.
Strategic context: Why Mayne Pharma?
Cosette Pharmaceuticals, a U.S.-based company focused on topicals, dermatology, and branded pharmaceuticals, has established strong internal R&D and manufacturing capabilities. The planned deal was designed to create a market leader in women’s health and dermatology, combining the strengths of both companies to expand reach, scale operations, and deliver innovation across global markets.
Cosette’s move to acquire Mayne Pharma reflects its efforts to accelerate expansion in high-growth specialty areas. If the companies were to combine, they would employ more than 800 professionals and operate two state-of-the-art, FDA-approved manufacturing facilities in Lincolnton, North Carolina, and Salisbury, South Australia.
While the deal is potentially off the table, we focus our attention on what has made Mayne Pharma an acquisition target – its IP assets. This article tracks Mayne Pharma’s patenting activity and its contributions to women’s health innovations, offering insight into how the company’s IP strategy has evolved over the past decade.
Mayne Pharma: Patenting activity
Mayne Pharma’s global patent activity peaked in 2015 and 2019. The 2015 surge coincided with the acquisition of the Doryx™ brand from Actavis, and the launch of a 60-person U.S. sales team while the surge in patent activity in 2019 coincided with a wave of new product launches, including TOLSURA and LEXETTE. The year marked a period of heightened development and regulatory activity, with several FDA approvals and manufacturing milestones that likely contributed to the uptick in patent grants.
Despite Mayne Pharma’s global operations, its patent activity for the past 10 years has been largely concentrated in the United States. Patent filings ceased after 2020 as Mayne Pharma shifted its focus from research and development to commercial execution. The company prioritized monetizing existing assets, particularly through the U.S. launch of Nextstellis, and began restructuring efforts, including the sale of its U.S. manufacturing arm. This strategic redirection away from pipeline expansion contributed to the absence of new patent activity from 2021 onwards.
Mayne Pharma: Top Law Firms
From 2015 to 2025, a small group of law firms handled the bulk of Mayne Pharma’s patent filings. At the forefront is Pearl Cohen Zedek Latzer Baratz, followed by Merchant & Gould P.C. and Sheppard, Mullin, Richter & Hampton.
Mayne Pharma: Top Technology Areas
Mayne Pharma’s U.S. patent activity from 2015 to 2025 is primarily concentrated in pharmaceutical preparations, with nearly half of its filings related to compounds for mental, dental, or toiletry purposes (A61K). A substantial share also falls under specific therapeutic activities of chemical compounds (A61P). These categories highlight the company’s strong emphasis on drug composition and delivery methods, as well as the development of new formulations for various medical conditions, respectively.
Additional filings in cosmetics and toiletry preparations (A61Q) suggest broader interests in personal care, while limited activity in packaging technologies (B65B) and storage containers (B65D) points to peripheral innovation supporting product delivery and logistics.
Patents reshaping women’s health
A new wave of global patents is driving innovation in women’s health, offering safer, more targeted treatments for diverse patient needs. From simplified rosacea therapies for older adults to stable corticosteroid foams and pediatric-friendly liquid spironolactone, these breakthroughs reflect a broader push toward personalized and accessible care in dermatology and beyond.
A gentle alternative for sensitive, aging skin
Rosacea is often characterized by redness and dryness of the face, commonly occurring among adults from the ages of 30 to 50. Standard treatments include a combination of oral or topical antibiotics, steroids, and anti-infectious agents. However, these treatments carry risks such as skin irritation and thinning for elderly patients who are 65 years and older due to the more fragile and sensitive nature of their skin.
U.S. Patent No. 11,865,100 offers a simple regimen for the treatment of rosacea for the elderly using a formulation with 2.5% to 10% benzoyl peroxide as its only active ingredient. The treatment method involves applying the formulation once daily for at least two weeks. The success of the treatment was determined based on the improvement of skin clarity measured through the Investigator Global Assessment (IGA) score (Fig. 1) and the decrease in inflammatory lesions (Fig. 2) measured among patients who are 65 years and older.
The regimen is also extensive in terms of its treatment scope. It can serve as a first-line therapy for treating the following forms of rosacea: vascular (facial redness), inflammatory (pus-filled bumps), phymatous (enlarged pores and thickened skin), or ocular (rosacea in the eye region).
The patent, titled “Method for treatment of rosacea in patients aged 65 years and older,” was filed on January 21, 2021 and granted on January 9, 2024. The inventors are Ofer Toledano, Ofra Levy-Hacham, Ori Nov, and Vered Ram. Legal representation was provided by Pearl Cohen Zedek Latzer Baratz LLP, with attorneys Larry Vierra, Brian Marcus, and Kathryn Piffat et al. listed on the application.
Stronger, more stable foam treatment for eczema and psoriasis
Corticosteroids, such as halobetasol, are compounds used to treat inflammatory skin diseases, such as eczema and psoriasis. Corticosteroid ointments are often produced as foam-based compositions, but there are issues concerning the deactivation of these compounds during manufacturing, canning, and storage processes.
U.S. Patent No. 11,020,407 presents a method for treating various skin diseases using a foam-based halobetasol propionate composition. The said halobetasol foam demonstrated an improved predicted shelf-life of over 36 months, in comparison to the usual 12 to 18 months. Notably, the composition’s pH also remained stable even beyond 18 months despite its lack of a buffer.
Furthermore, the patent’s halobetasol foam also showed a strong clinical efficiency in treating plaque psoriasis. It managed to achieve a higher treatment success rate (52.2%) than Olux® E Foam (16%) and Temovate® Ointment (31%) despite the fact that a stronger corticosteroid (clobetasol) served as the active compound in the mentioned products.
The patent, titled “Corticosteroid containing foam compositions and method manufacture thereof,” was filed on November 30, 2016 and granted on June 1, 2021. The inventors are Robert Gauthier and James Hammer. Legal representation was provided by Nath, Goldberg & Meyer, with attorneys Gary Nath, Stanley Protigal, and Alvin Tanenholtz et al. listed on the application.
Safer and easier way to take Spironolactone
Spironolactone is used for the treatment of various skin diseases, liver cirrhosis, heart failure, and chronic lung disease. Commercially, spironolactone is available as tablets with no aqueous-based counterparts, which is a problem for pediatric patients or adult patients with severe heart failure. In such cases, a liquid formulation is usually prepared by a pharmacist. However, this practice carries the risk of microbial contamination, potential errors in computation, and an effect on the stability of spironolactone.
To address the concerns associated with its tablet form, U.S. Patent No. 11,491,166 presents a stable and ready-to-use liquid formulation of spironolactone. Included in the formulation is xanthan gum, which is an agent that enables uniform drug distribution within five seconds of shaking (Fig. 2). Sweeteners and flavoring agents are also added for increased compliance by pediatric patients.
The buffers included in the formulation also enables the long-term stability of spironolactone in storage conditions. In addition to easier drug administration, the patent’s formulation also features the increased absorption of spironolactone into a patient’s bloodstream by about 15% to 37% more than tablets. This enhanced bioavailability of the drug may improve treatment outcomes, particularly for patients experiencing problems with absorbing the tablet form of the drug.
The patent, titled “Spironolactone aqueous compositions,” was filed on December 4, 2020 and was granted on November 8, 2022. The inventors are Anthony Pipho and Michael Paul DeHart. Legal representation was provided by Merchant & Gould P.C., with attorneys Erich Gess, John Clifford, and Bruce Boggs et al. listed on the application.
Future outlook
The outcome of Mayne Pharma’s legal dispute with Cosette Pharmaceuticals could set a key precedent for mergers and acquisitions in heavily regulated industries like pharmaceuticals. If the court rules in Mayne’s favor, Cosette may be required to proceed with its $672 million takeover. A ruling for Cosette, however, would force Mayne to seek alternative buyers or rebuild its strategy independently.
The Supreme Court is set to hear arguments on the validity of Cosette’s termination notice on September 9. The decision is expected to carry broader implications for how “material adverse change” clauses are interpreted and enforced in future life sciences transactions.
