A CBD-Hydroxychloroquine Combination Drug Was Safe and Well-Tolerated in Healthy Volunteers | Research

The takeaway

A Phase I trial found that IHL-675A, a fixed-dose combination of CBD and hydroxychloroquine for inflammatory conditions, was generally well-tolerated with a safety profile similar to each drug given separately.

Pharmaceutical researchers and people interested in CBD-based medicine development.

No serious adverse events in any treatment arm

What the researchers found

IHL-675A was generally well-tolerated with no serious adverse events. Both CBD and HCQ were bioavailable when co-administered. CBD exposure was approximately 50% higher (Cmax) in the combination versus Epidiolex alone, while HCQ exposure was slightly decreased (15% lower AUC). The 90% CIs for both drugs extended beyond standard bioequivalence acceptance intervals.

Why it matters

This is the first clinical trial of a fixed-dose CBD-hydroxychloroquine combination being developed for rheumatoid arthritis and other inflammatory conditions. The safety and PK data support continued development toward efficacy trials.

The numbers in context

36 participants, 12 per arm. No SAEs. CBD Cmax approximately 50% higher in combination vs Epidiolex alone. HCQ AUC approximately 15% lower in combination vs Plaquenil alone. 90% CIs outside 80-125% bioequivalence range for both drugs.

How the study worked

Phase I, randomized, open-label, comparator-controlled trial with 36 healthy volunteers assigned 1:1:1 to IHL-675A (150mg CBD + 200mg HCQ), Plaquenil alone (200mg HCQ), or Epidiolex alone (150mg CBD). Safety, pharmacokinetics, and metabolite profiles assessed over 4 weeks.

What this study cannot tell us

Phase I in healthy volunteers only (no patients with inflammatory conditions). Small sample size. Open-label design. The increased CBD and decreased HCQ exposures in the combination need to be evaluated for clinical significance. Single-dose study.

How to read the evidence

Phase I trial with 36 participants. Provides safety and PK data only; efficacy has not been assessed.

When this study was published

Published in 2025.

The bigger picture

Combining CBD with established anti-inflammatory drugs is a growing area of pharmaceutical development. If CBD enhances or complements the anti-inflammatory effects of hydroxychloroquine, this combination could offer benefits for conditions like rheumatoid arthritis with potentially fewer side effects than current regimens.

Questions still open

Will the altered PK profile of the combination affect efficacy? Does the 50% higher CBD exposure translate to greater anti-inflammatory effect or increased side effects?

Common questions

What is this drug for?

IHL-675A combines CBD and hydroxychloroquine in a single capsule for treating inflammatory conditions like rheumatoid arthritis. It is still in early-stage clinical development.

Why combine CBD with hydroxychloroquine?

Both have anti-inflammatory properties through different mechanisms. The combination aims to provide enhanced anti-inflammatory effects while potentially allowing lower doses of each drug.

Read the original research

An open-label phase I comparator-controlled clinical trial to assess tolerability and pharmacokinetics of IHL-675 A a fixed dose combination of cannabidiol plus hydroxychloroquine in healthy volunteers.

Scientific reports, 15(1), 19357

View on PubMed ↗Publisher’s paper ↗

Citation

Mbogo, George Williams; Kroner, Pia; Walsh, Rosemarie; Newchurch, Jonathan; Bleackley, Mark Robert. (2025). An open-label phase I comparator-controlled clinical trial to assess tolerability and pharmacokinetics of IHL-675 A a fixed dose combination of cannabidiol plus hydroxychloroquine in healthy volunteers.. Scientific reports, 15(1), 19357. https://doi.org/10.1038/s41598-025-04573-5