Subcutaneous Lidocaine-HP-β-CD: A Potential Disease-Modifying Breakthrough for Post-COVID Condition

Highlights

Significant Quality of Life Gains

At 36 weeks, patients showed a physical component score increase of 4.13 and a mental component score increase of 7.00 on the SF-12 scale (p < 0.0001), indicating substantial clinical improvement.

Broad Symptomatic Relief

Twenty-seven out of thirty assessed symptoms, including fatigue, cognitive impairment, and autonomic dysfunction, showed significant improvement compared to the pre-treatment period.

Scalable Home-Based Intervention

The subcutaneous delivery method combined with a cyclodextrin carrier allowed for safe, self-administered long-term treatment with no serious adverse events reported.

Background: The Unmet Need in Post-COVID Care

Post-COVID condition (PCC), colloquially known as Long COVID, remains one of the most significant public health challenges following the SARS-CoV-2 pandemic. Characterized by persistent symptoms lasting more than three months, PCC involves a complex interplay of systemic inflammation, immune dysregulation, and autonomic dysfunction. Patients often suffer from profound fatigue, cognitive deficits (brain fog), and post-exertional malaise, which severely impact their quality of life and ability to work. Despite the scale of the crisis, there are currently no globally approved disease-modifying treatments for PCC. Most clinical management remains supportive or symptomatic. The search for a scalable, safe, and effective intervention led researchers to investigate the potential of lidocaine, a well-known local anesthetic with systemic anti-inflammatory and neuromodulatory properties, enhanced by a cyclodextrin delivery system.

Study Design and Methodology

This 36-week observational interrupted time series study was conducted at a Dutch outpatient clinic between August 2024 and April 2025. The study enrolled 103 adults with physician-diagnosed post-COVID condition. To establish a robust baseline, the protocol began with a 4-week pre-treatment observation phase.

The Intervention Protocol

The treatment utilized a 5% lidocaine solution formulated with hydroxypropyl-β-cyclodextrin (HP-β-CD). HP-β-CD is a functional excipient that improves the solubility and stability of lidocaine, potentially facilitating a more controlled release. The home-based subcutaneous administration followed a three-phase protocol:
1. Phase 1 (Weeks 1-7): 500 mg every other day.
2. Phase 2 (Weeks 7-14): 500 mg daily.
3. Phase 3 (After Week 14): Up to 1000 mg daily in patients identified as non-responders.

Outcome Measures

The primary endpoint was health-related quality of life (HRQoL), measured by the Short Form-12 (SF-12) Physical and Mental Component Summary scores. Secondary outcomes included a daily app-based questionnaire tracking 30 specific symptoms and a rigorous assessment of adverse events.

Key Findings: Quantifying the Impact

The study population had a median symptom duration of over 31 months, representing a cohort with chronic, stable PCC. Despite the long duration of illness, the response to the lidocaine-HP-β-CD intervention was significant and progressive.

Quality of Life Improvements

The physical component summary (PCS) and mental component summary (MCS) of the SF-12 showed statistically significant increases at both the 24-week and 36-week marks:
– At 24 weeks: PCS increased by 2.20 points; MCS increased by 5.16 points.
– At 36 weeks: PCS increased by 4.13 points; MCS increased by 7.00 points.
All improvements reached a p-value of < 0.0001. These gains are particularly noteworthy given that even small point increases in SF-12 scores are associated with meaningful improvements in daily functioning and reduced healthcare utilization.

Symptom Burden Reduction

By week 24, 27 of the 30 monitored symptoms showed statistically significant improvement. Key improvements were noted in fatigue, post-exertional malaise, and cognitive dysfunction. The interrupted time series analysis confirmed that these changes were associated with the initiation of treatment rather than the natural history of the disease.

Safety and Tolerability

The intervention was generally well-tolerated. While 89% of participants experienced mild adverse events, these were overwhelmingly local injection-site reactions (redness, swelling, or itching). Crucially, no serious adverse events (SAEs) or systemic lidocaine toxicity were reported throughout the 36-week period, supporting the safety of home-based subcutaneous administration.

Expert Commentary: Mechanistic Insights

The efficacy of systemic lidocaine in PCC may be attributed to several synergistic mechanisms. Lidocaine is known to block voltage-gated sodium channels (VGSCs), which are involved not only in pain signaling but also in the activation of immune cells. By modulating these channels, lidocaine may dampen the chronic neuroinflammation and microglial activation suspected to drive PCC symptoms. Furthermore, lidocaine has been shown to exert inhibitory effects on pro-inflammatory cytokines such as IL-6 and TNF-alpha, which are frequently elevated in patients with persistent viral sequelae.

The use of HP-β-CD is also significant. Beyond its role as a carrier, cyclodextrins may have independent biological effects, including lipid membrane modulation. This study suggests that the combination provides a steady-state therapeutic effect that resets autonomic balance, potentially addressing the underlying dysautonomia seen in these patients.

Conclusion and Clinical Implications

The results of this 36-week study suggest that subcutaneous lidocaine-HP-β-CD is a promising, scalable, and safe intervention for post-COVID condition. The progressive improvement in both physical and mental health scores suggests a cumulative therapeutic effect that persists over time. While the observational nature of the interrupted time series design is a limitation compared to a randomized controlled trial (RCT), the strength of the statistical significance and the consistency of symptom improvement provide a compelling case for further investigation. For clinicians, this study offers a potential pathway for managing a patient population that has largely been left without effective pharmaceutical options.

Funding and References

Funding: Excellent Care Clinics funded the treatment provided in this study.
ClinicalTrials.gov: Data associated with this study protocol were managed through Dutch outpatient clinic registries.

References:
1. Oostwouder CJ, et al. Effect of subcutaneous lidocaine-hydroxypropyl-β-cyclodextrin (HP-β-CD) on quality of life in patients with post-COVID condition: a 36-week observational interrupted time series study. EClinicalMedicine. 2025;90:103681. doi:10.1016/j.eclinm.2025.103681.
2. Davis HE, et al. Long COVID: major findings, mechanisms and recommendations. Nature Reviews Microbiology. 2023;21(3):133-146.
3. Weinberg L, et al. Pharmacokinetics and pharmacodynamics of systemic lidocaine: A contemporary review. Anaesthesia and Intensive Care. 2015;43(1):11-20.