InhaleRx (ASX: IRX) unveils oral esketamine therapy for depression but stock sinks 22% amid investor caution

InhaleRx Limited (ASX: IRX) has expanded its clinical development pipeline with a new investigational oral therapy called SRX-25, targeting the multibillion-dollar Treatment-Resistant Depression (TRD) market. The announcement marks a strategic shift for the Australian healthcare microcap, positioning it closer to mainstream psychiatric drug developers through a scalable, fixed-dose combination format. However, the update was not immediately rewarded by the market. Shares of InhaleRx dropped sharply by 22.22% on November 26, 2025, closing at AUD $0.028. That fall marks a 12-month decline of more than 28 percent, underscoring investor concerns over capital dilution, pipeline risk, and execution timelines.

Despite this selloff, InhaleRx’s entry into the oral ketamine segment is notable for its potential to unlock a large segment of underserved patients. The company aims to deliver the rapid-onset antidepressant benefits of esketamine in a tablet format that removes the need for supervised intranasal dosing in clinical settings, a critical barrier to adoption in current TRD care pathways.

How does SRX-25 aim to disrupt the current treatment-resistant depression market?

SRX-25 is formulated as a fixed-dose oral combination of esketamine and a proprietary CYP450 inhibitor. This approach is designed to overcome the pharmacokinetic limitations that have prevented esketamine from being administered effectively in oral form. By reducing the drug’s metabolism through enzyme inhibition, SRX-25 allows a larger proportion of esketamine to reach systemic circulation while preserving its fast-acting antidepressant effects.

The current market leader, Johnson & Johnson’s Spravato, is an intranasal esketamine product that must be administered under medical supervision. While clinically effective, its mode of delivery limits accessibility and uptake. Long clinic visits, restricted infrastructure, and stigma remain formidable hurdles for patients with TRD. SRX-25 offers the possibility of self-administration in outpatient settings, significantly widening the addressable population if successful.

InhaleRx believes this format could provide superior adherence and lower the overall cost of care while still delivering the critical rapid-onset properties of esketamine that have shown promise in TRD patients. If clinical trials validate its effectiveness, SRX-25 may enable broader deployment of ketamine-class drugs in psychiatric care.

What are the regulatory and clinical trial strategies for SRX-25?

The development of SRX-25 will proceed under the United States Food and Drug Administration’s 505(b)(2) regulatory pathway, a mechanism designed to reduce development costs and timelines by allowing developers to rely on existing safety and efficacy data of previously approved compounds. This pathway enables InhaleRx to bypass parts of early-stage development and instead focus on clinical differentiation through formulation and delivery.

The clinical plan includes a Phase 1 pharmacokinetic study to confirm oral bioavailability, followed by a Phase 2 proof-of-concept trial to assess efficacy and patient outcomes. The objective is to achieve Phase 3 readiness within two to three years from the start of the Phase 1 trial. InhaleRx has also indicated that patent filings to protect the formulation and its method of use are underway, signaling a long-term IP strategy tied to market exclusivity.

Alongside clinical progress, InhaleRx has positioned the asset for future monetization opportunities, including licensing, co-development partnerships, or asset sale. The company is emphasizing optionality as a way to maximize shareholder value, particularly in the event of positive Phase 2 results.

What financial backing supports SRX-25’s development?

Development costs for SRX-25, including non-clinical activities, manufacturing, and the Phase 1 and Phase 2 studies, will be funded through the company’s long-standing agreement with the Linlithgow Family Office. InhaleRx announced that it had secured an additional AUD $12.6 million under the existing facility, raising the total funding capacity to AUD $52.3 million.

In consideration for increasing the facility, InhaleRx has granted Linlithgow 10.9 million new options on the same terms as previous tranches. When added to the options already held by the investor, these securities represent approximately 19.9 percent of the company’s outstanding ordinary shares following a recent placement. The options will vest upon the completion of Phase 2 trials for SRX-25, IRX-211, and IRX-616a.

This structure aligns repayment of the funding facility with asset milestones, suggesting a model where option conversion at a 10 percent discount to the 90-day volume-weighted average price could be used to repay loans, thereby reducing future interest-bearing debt obligations.

What are the capital raise terms and rebranding plan?

InhaleRx has also launched a capital raise to strengthen working capital. The company secured firm commitments to raise AUD $750,000 via a share placement at AUD $0.025 per share. This price represents a 30.6 percent discount to the stock’s last close prior to the announcement and a 19 percent discount to the 30-day average trading price. Participants in the placement will receive one free option for every two shares subscribed, with an exercise price of AUD $0.042 and a two-year expiry period.

In addition, InhaleRx plans to offer eligible shareholders a non-renounceable rights issue to raise up to AUD $250,000 on the same terms as the placement. This offer is scheduled to open on December 5 and close on December 17, 2025. The company will also allow oversubscription for shortfall shares, which may be issued with matching options. Peak Asset Management has been appointed lead manager for both the placement and the rights issue.

As part of its strategic repositioning, InhaleRx has proposed a rebrand to Nexalis Therapeutics Limited, subject to shareholder approval. The proposed ticker symbol “NX1” has already been reserved with the Australian Securities Exchange. The rebranding reflects the company’s diversification beyond inhaled drug delivery and into broader clinical-stage psychiatric therapeutics.

What does the stock performance reveal about investor sentiment?

InhaleRx’s stock fell by more than 22 percent following the announcement, closing at AUD $0.028 with over 312,000 shares traded, significantly higher than the four-week average volume. Year-to-date, the stock has declined approximately 20 percent, and over a 12-month period, it has underperformed the ASX 200 index by 31 percent.

The stock’s one-year trading range of AUD $0.018 to AUD $0.048 suggests high volatility, typical for early-stage biotech firms. The company has a market capitalization of just over AUD $6 million, with 217.95 million shares outstanding. Earnings per share are currently negative at AUD –$0.006, and the book value per share stands at AUD –$0.004.

These metrics signal a speculative investment profile. No major broker coverage exists, and institutional ownership appears limited. However, analysts who monitor the Australian biotech sector say the upcoming pharmacokinetic trial for SRX-25 could serve as a major inflection point. If successful, it may trigger broader investor interest in the company’s growing central nervous system portfolio.

How does SRX-25 fit into the broader InhaleRx pipeline and roadmap?

InhaleRx’s development strategy includes three primary assets: IRX-211 for breakthrough cancer pain, IRX-616a for panic disorder, and SRX-25 for treatment-resistant depression. All three are advancing through capital-efficient programs designed to reduce early development risk. The shared funding model with Linlithgow and reliance on the 505(b)(2) pathway reflect a lean approach to clinical advancement.

SRX-25, however, represents a shift toward mainstream psychiatric disorders with large commercial markets. If successful, the drug could serve as a cornerstone in InhaleRx’s repositioning as a psychiatric-focused drug development company. The oral delivery format, scalable formulation, and potential for outpatient use place it in contrast to existing treatment models, and could be attractive to licensing partners or acquirers.

The proposed rebrand to Nexalis Therapeutics signals a long-term commitment to mental health innovation, expanding beyond the company’s roots in inhaled formulations. While the path forward includes regulatory, clinical, and capital risks, SRX-25 gives InhaleRx a product candidate with large-scale applicability in a market eager for innovation.

What are the key takeaways from InhaleRx’s SRX-25 announcement and stock performance?

• InhaleRx Limited (ASX: IRX) has introduced SRX-25, an oral fixed-dose esketamine therapy aimed at Treatment-Resistant Depression, expanding beyond its traditional inhaled drug focus.

• SRX-25 combines esketamine with a CYP450 inhibitor to improve oral bioavailability and aims to offer a more accessible alternative to Johnson & Johnson’s intranasal Spravato.

• The global TRD market is projected to double to USD $4.06 billion by 2030, positioning SRX-25 to potentially capture a significant portion of underserved outpatient demand.

• The asset will be developed through the U.S. FDA’s 505(b)(2) pathway, with a Phase 1 pharmacokinetic study and Phase 2 proof-of-concept trial planned.

• InhaleRx has secured an additional AUD $12.6 million from the Linlithgow Family Office, bringing its total funding facility to AUD $52.3 million for clinical programs including SRX-25.

• A capital raise of AUD $750,000 through a discounted share placement and an AUD $250,000 rights issue is underway to support non-clinical operations.

• Participants in both the placement and rights issue will receive free-attaching options exercisable at AUD $0.042, expiring in two years.

• The company plans to rebrand as Nexalis Therapeutics Limited and change its ASX ticker to NX1, reflecting its pivot toward scalable psychiatric therapeutics.

• IRX stock fell 22.22% on November 26, 2025, closing at AUD $0.028, with a one-year decline of 28.21% and a trailing performance well below the ASX 200.

• Investors remain cautious amid high dilution, speculative financials, and preclinical risk, though analysts suggest SRX-25 could be an inflection point if trial results validate its oral formulation strategy.