Part 4: LXB as Effective as SXB for Cataplexy, EDS, With Less Sodium

Readers can check out part 1, part 2, and part 3 now.

For patients with cataplexy and excessive daytime sleepiness (EDS), just taking their medication can have long-term health effects due to increased sodium in the drug sodium oxybate (SXB).

However, the efficacy of low sodium oxybate (LXB) for the treatment of cataplexy and EDS was found to be consistent with SXB, even though LXB has 92% less sodium the SXB, according to a study in Sleep.

In part 4 of this 4-part series, Richard K Bogan, MD, FCCP, FAASM, fellow of the American College of Chest Physicians and the American Academy of Sleep Medicine, principal of Bogan Sleep Consultants LLC, and clinical associate professor at the University of South Carolina School of Medicine, offered insight into his recent study on LXB and regular SXB during an interview with The American Journal of Managed Care^®.

Dr. Richard K Bogan | © Bogan Sleep Consultants

Narcolepsy is a chronic neurologic disorder that seriously impairs quality of life, productivity, and social functioning, necessitating long-term treatment in multiple patients, and possesses a global estimated prevalence of 0.02% to 0.067%. One symptom of narcolepsy is cataplexy, for which SXB is an approved treatment.

SXB treatment contributes to 1100 to 1640 mg of daily sodium intake, and sodium intake increases the risk of hypertension and cardiovascular outcomes, especially stroke, separate from blood pressure.

“There’s a lot of literature that says that sodium intake has an effect on chronic disease, mainly cardiovascular and renal status," said Bogan. "Chronic, higher sodium levels of intake put people at risk primarily for cardiovascular problems and hypertension. Of course, hypertension can lead to vascular disease, strokes, chronic renal failure; all of those are important."

Exposure to high-sodium medications such as SXB is an extra contribution to total daily sodium intake, and high sodium intake over a lifetime, as what may be required by patients with narcolepsy, may confer risk in younger, apparently healthy individuals. So, patients with narcolepsy are at higher risk of developing cardiovascular and cardiometabolic disease.

“We all recognize that monitoring sodium intake, particularly in vulnerable populations. Patients with narcolepsy, interestingly, have a higher prevalence of comorbidities, and their disorder is lifelong,” Bogan said.

“These oxybate molecules are indicated for the treatment in patients with narcolepsy, and, interestingly, narcolepsy patients have a higher prevalence of cardiovascular disease, diabetes, and obesity. So, when we’re using medication for the rest of their lives, potentially, we pay a lot of attention to sodium intake,” he continued.

Bogan went on to say that individuals with narcolepsy over the years sometimes develop some other disorders that sodium intake can have an impact on that health care providers take into an account.

Another interesting finding was “dipping,” which is when a person's heart rate and blood pressure drop when they go to sleep at night. This can be used as a measure of sleep quality as to whether you’re in deep sleep or not. Non-dipping is not good, and narcolepsy patients are non-dippers as a group, Bogan said, so anything that can be done to decrease cardiovascular risk is something they keep in mind.

Some individuals have autonomic instability that may be related to their narcolepsy. He went on to say, “so when they stand up, they have postural syncope. We call it neurocardiogenic syncope, and they do tilt table tests on some of these folds and their blood pressure drops.”

He said that some of those people might need higher sodium levels. In those who have narcolepsy, he would opt for the higher sodium molecule, otherwise opting for the lower sodium molecule in people who will be taking the medication forever for the health and safety benefit.

When it came to explaining the responsibilities patients have for maintaining their own healthy sodium levels, Bogan explained that most items are well labeled as long as a patient pays attention to serving sizes.

Bogan also said that it's recommended that people maintain a healthy lifestyle to keep the sodium load at a reasonable level. A chronically high sodium load might pose a risk of a changing setpoint of blood pressure until it reaches a point where an individual would be considered clinically at risk for hypertension.

Medicine, however, is tricky because sodium content isn’t always labeled in medicine like it is in food. Bogan emphasized that oxybate is the main, activated molecule for the medication, despite the amount of sodium it’s taken with.

“I think the bottom line is that oxybate is an important molecule that has been very effective in our patients, and treating cataplexy and sleepiness and, you know, early on the molecule was developed as sodium oxybate,” emphasized Bogan.

Participants in this study showed cardiovascular and cardiometabolic comorbidities that were seen in prior research.

“Given these cardiovascular risk factors, the 92% reduction of sodium intake with LXB relative to SXB treatment may be beneficial for mitigating the risk of cardiovascular events in a population with narcolepsy,” highlighted the study authors.

In reference to Bogan’s own practice, he said, “I take all that into account—that the big impact of sodium, obviously, on the front end is going to be blood pressure, and high blood pressure can lead to some of these other things,” indicating that each patients’ circumstances are ultimately responsible for a health care provider’s decision on what care is best for that patient.

The efficacy of LXB for the treatment of cataplexy and EDS in adults with narcolepsy was shown in this placebo-controlled, double-blind, randomized withdrawal study.

“LXB represents a novel oxybate treatment option for patients with narcolepsy, with the benefit of 92% less sodium,” concluded the researchers.

Reference

Bogan RK, Thorpy MJ, Dauvilliers Y, et al. Efficacy and safety of calcium, magnesium, potassium, and sodium oxybates (lower-sodium oxybate [LXB]; JXP-258) in a placebo-controlled, double-blind, randomized withdrawal study in adults with narcolepsy with cataplexy. Sleep. Published online October 14, 2020. doi:10.1093/sleep/zsaa206