Rilmenidine Well-Tolerated in HD Patients, but More Studies Needed, Researchers Say

Researchers have found that rilmenidine, a blood pressure medicine, was relatively safe and well-tolerated by Huntington’s disease (HD) patients in a small study. However, its effectiveness in treating the disease remains unknown and warrants further investigation.

The study, “An open-label study to assess the feasibility and tolerability of rilmenidine for the treatment of Huntington’s disease,” appeared in the Journal of Neurology.

Previous studies suggested that rilmenidine could regulate the course of HD in animal models of the disease. Testing the drug’s effectiveness in HD patients requires large numbers of patients and long-term follow-up, previous studies have found.

But, “before embarking on studies of this type, it is important to ascertain that the drug to be trialled is well tolerated and the study feasible,” the authors wrote.

In this study, a team of researchers at the University of Cambridge in the U.K. tested the safety and tolerability of rilmenidine in a small group of patients with HD.

The single-center, open-label study — meaning that both patients and researchers know which treatment is being administered — recruited 18 non-demented patients with mild to moderate HD from Addenbrooke’s Hospital.

After enrollment, patients received oral daily doses of 1 mg of rilmenidine for six months, followed by a 2 mg dose for 18 months. After the 24 months of treatment, they underwent a three-month washout period.

Researchers evaluated patients at baseline and then every three months during the first year. After the first year, they assessed participants every six months and at the 27th month (after the three-month wash-out period).

The study’s primary outcome determined the number of withdrawals and serious adverse events, and secondary endpoints included safety and changes in disease parameters, including motor, cognitive, and functional performance, as well as structural magnetic resonance imaging and analysis of metabolites in patients’ blood.

Of an initial pool of 18 patients, 12 completed the study.

Those who withdrew did so due to “problems tolerating study procedures (MRI, and venipuncture [blood sample collection]), depression requiring hospital admission and logistical reasons,” authors wrote.

The results suggest that rilmenidine is relatively safe and well-tolerated in HD patients, and no drug-related serious adverse events occurred. But researchers were unable to “ascertain whether there was any efficacy of this agent as the trial was not designed to test for drug-related changes in secondary outcome measures.”

Despite this limitation, they observed that patients exhibited a lower rate of brain alterations, including brain atrophy, and a smaller decline in two tools measuring clinical features of the disease — the Mini–Mental State Examination (MMSE) and Unified Huntington’s Disease Rating Scale (UHDRS) scores — compared to previous studies.

They observed no alterations in blood metabolites and cognitive function over time.

Overall, these results may “encourage undertaking further studies with this agent in larger, randomised, placebo-controlled trials,” the authors wrote.