Clinical Trials & Cannabinoid Safety: The MRX1 Research Programme

While real-world evidence (RWE) from patient surveys is valuable, establishing the safety, efficacy, and dosage guidelines for cannabis-based medicines requires rigorous clinical trial evaluation. In the UK, major pharmaceutical developments are underway to move cannabinoid formulations through formal clinical pathways.

This article reviews the clinical trial landscape for cannabis-based products, focusing on the research programme for MRX1, a proprietary CBD oral solution, its safety profile in Phase I testing, and upcoming NHS-backed Phase II trials.

The Clinical Development Pathway for Cannabinoids

In the UK, the majority of prescribed medical cannabis is accessed as “unlicensed” medicines. To gain full licensing and widespread NHS funding, developers must subject their drug candidates to the standard pharmaceutical trial phases regulated by the Medicines and Healthcare products Regulatory Agency (MHRA):

Phase I (Safety & Pharmacokinetics): Evaluates safety, tolerability, absorption, and distribution in a small group of healthy volunteers.
Phase II (Proof of Concept & Efficacy): Tests the drug in a larger group of patients (e.g., 50–100) suffering from the target condition to assess efficacy and refine dosage.
Phase III (Confirmatory Trials): Compares the drug against standard treatments or placebos in large, multi-center cohorts (e.g., hundreds or thousands of patients).

Rather than pursuing a full de-novo application, some developers use the regulatory 505(b)(2) pathway. This allows them to build upon existing safety and toxicity data of approved cannabinoid medicines, significantly accelerating the clinical development timeline.

Phase I Safety Findings for MRX1 CBD Oral Solution

Ananda Pharma has recently completed the Phase I preparatory phase for its flagship MRX1 CBD oral solution. Conducted in partnership with clinical research organizations, the Phase I pharmacokinetic trial yielded several significant safety and tolerability results:

Safety Profile: Across the cohort of healthy participants who received twice-daily doses of MRX1 (tested at 2.5 mg/kg and 7.5 mg/kg over six days), all treatment-emergent adverse events were classified as mild (Grade 1).
No Serious Adverse Events: No moderate or severe events, serious adverse events (SAEs), or trial discontinuations were recorded.
Liver Function Safety: Regulators examine liver enzymes closely when evaluating high-dose cannabinoid therapies (as elevated enzymes can indicate liver stress). The MRX1 trial recorded no clinically significant changes in liver function, supporting its long-term safety profile.
Pharmacokinetics: The absorption data confirmed that MRX1 achieves reliable, predictable blood levels under both fed and fasted conditions.

Forthcoming Phase II Clinical Trials in the UK

Building on the Phase I safety data, the MRX1 formulation is transitioning into Phase II clinical trials at the University of Edinburgh, backed by NHS and UK government research funding. These trials will evaluate the drug’s efficacy across two distinct therapeutic indications:

1. The ENDOCAN Trial (Endometriosis-Associated Pain)

Cohort: Up to 100 women suffering from endometriosis-associated chronic pelvic pain.
Focus: Chronic pelvic pain associated with endometriosis is often resistant to standard hormonal and analgesic treatments. The trial will evaluate whether MRX1 can provide significant pain reduction and improve quality of life.
Funding: Co-funded by the Chief Scientist Office (CSO) and conducted across NHS Lothian and NHS Grampian.

2. The ACTION Trial (Chemotherapy-Induced Peripheral Neuropathy)

Cohort: Patients experiencing peripheral neuropathy (nerve damage, pain, numbness) induced by chemotherapy agents.
Focus: Chemotherapy-induced neuropathy is a common, debilitating side effect of cancer treatment with limited therapeutic options. The trial will assess the efficacy of MRX1 in mitigating neuropathic pain.
Funding: Funded by the National Institute for Health and Care Research (NIHR).

Safety Monitoring and the MHRA Yellow Card Scheme

Although clean Phase I safety data is encouraging, patients participating in clinical trials or taking prescribed unlicensed CBPMs are monitored continuously for adverse reactions.

In the wider patient population, safety monitoring relies on active pharmacovigilance. If you are prescribed medical cannabis in the UK and experience any side effects, you should report them to the MHRA Yellow Card Scheme. These reports help regulatory authorities build a comprehensive database of cannabinoid interactions, safety profiles, and efficacy trends.

Overview of MRX1 Trial Phases

Trial Phase	Indication / Focus	Status	Participants	Research Partners
Phase I	Pharmacokinetics & Safety (Tolerability)	Completed	20 (Healthy)	Southern Star Research
Phase II (ENDOCAN)	Endometriosis-Associated Chronic Pain	Dosing in 2026	Up to 100 (Patients)	NHS Lothian, Univ. of Edinburgh
Phase II (ACTION)	Chemotherapy-Induced Neuropathy	Dosing in 2026	Target Cohort	NIHR, Univ. of Edinburgh

Disclaimer: MCRx is an independent educational information directory, not a clinical trial provider. The information provided is based on published clinical study updates. Medical cannabis remains a controlled, prescription-only substance in the UK. Always consult your clinic’s physician for medical advice.