Poster
129
(#129) Evaluating the Impact of Switching From High-Sodium Oxybate to Low-Sodium Oxybate on Ambulatory Blood Pressure in People With Narcolepsy
Psych Congress 2025
Abstract: Background: Excess sodium intake increases risk of hypertension/cardiovascular disease, which are common comorbidities in people with narcolepsy (PwN).
Methods: This study (NCT05869773; XYLO) evaluated blood pressure (BP) in PwN (aged 18-70 years) with systolic BP (SBP) 130−155 mmHg taking twice-nightly high-sodium oxybate (SXB) 6-9 g (≥6 weeks) switching to low-sodium oxybate (LXB; ≈6 weeks). Baseline-adjusted change from baseline to end-of-treatment in mean 24-hour ambulatory SBP (primary endpoint) and daytime ambulatory, seated resting ("office"), and nighttime ambulatory SBP (secondary endpoints) were assessed. Exploratory endpoints were diastolic BP (DBP) changes. An interim analysis (prespecified at 75% completers) was performed; one-sided and two-sided/nominal P-values for SBP and DBP changes, respectively, are reported.
Results: Mean±SD baseline office SBP and DBP were 138.0±5.7 and 85.2±6.6 mmHg, respectively, for 43 PwN (mean age, 45 years; 65% female; antihypertensive use, 33%). Switching to LXB reduced mean±SD pharmaceutical sodium by 1338.8±190.7 mg. Median reduction in 24-hour urinary sodium was 1288.0 mg. LSM change (95% CI) in 24-hour SBP was −4.1 (−6.9, −1.4) mmHg; P=0.0019. Daytime/office/nighttime SBP changes were −5.1 (−7.8, −2.4) mmHg; P=0.0003/−9.2 (−11.9, −6.5) mmHg; P 0.0001/−2.0 (−5.3, 1.4) mmHg; P=0.1265. LSM change (95% CI) in mean 24-hour DBP was −2.3 (−4.1, −0.5) mmHg; P=0.0118. Daytime/office/nighttime DBP changes were −2.8 (−4.8, −0.9) mmHg; P=0.0045/−3.8 (−6.0, −1.6) mmHg; P=0.0014/−1.1 (−3.6, 1.5) mmHg; P=0.3993. Treatment-emergent adverse events (none serious) occurred in 40% of participants.
Conclusions: Switching from SXB to LXB reduced daily medication-related sodium intake in PwN and was associated with clinically meaningful office and ambulatory BP reductions.
Short Description: Excess sodium intake increases hypertension/cardiovascular disease risk, already elevated in people with narcolepsy (PwN) at baseline. Switching from high-sodium oxybate to low-sodium oxybate (LXB) in the XYLO study (NCT05869773) reduced mean 24-hour ambulatory systolic blood pressure (SBP) by 4.1 mmHg and mean seated resting ("office") SBP by 9.2 mmHg in PwN. Switching to LXB reduced medication-related sodium intake and was associated with clinically meaningful reductions in blood pressure, consistent with evidence on sodium reduction effects.
Name of Sponsoring Organization(s): Jazz Pharmaceuticals
Methods: This study (NCT05869773; XYLO) evaluated blood pressure (BP) in PwN (aged 18-70 years) with systolic BP (SBP) 130−155 mmHg taking twice-nightly high-sodium oxybate (SXB) 6-9 g (≥6 weeks) switching to low-sodium oxybate (LXB; ≈6 weeks). Baseline-adjusted change from baseline to end-of-treatment in mean 24-hour ambulatory SBP (primary endpoint) and daytime ambulatory, seated resting ("office"), and nighttime ambulatory SBP (secondary endpoints) were assessed. Exploratory endpoints were diastolic BP (DBP) changes. An interim analysis (prespecified at 75% completers) was performed; one-sided and two-sided/nominal P-values for SBP and DBP changes, respectively, are reported.
Results: Mean±SD baseline office SBP and DBP were 138.0±5.7 and 85.2±6.6 mmHg, respectively, for 43 PwN (mean age, 45 years; 65% female; antihypertensive use, 33%). Switching to LXB reduced mean±SD pharmaceutical sodium by 1338.8±190.7 mg. Median reduction in 24-hour urinary sodium was 1288.0 mg. LSM change (95% CI) in 24-hour SBP was −4.1 (−6.9, −1.4) mmHg; P=0.0019. Daytime/office/nighttime SBP changes were −5.1 (−7.8, −2.4) mmHg; P=0.0003/−9.2 (−11.9, −6.5) mmHg; P 0.0001/−2.0 (−5.3, 1.4) mmHg; P=0.1265. LSM change (95% CI) in mean 24-hour DBP was −2.3 (−4.1, −0.5) mmHg; P=0.0118. Daytime/office/nighttime DBP changes were −2.8 (−4.8, −0.9) mmHg; P=0.0045/−3.8 (−6.0, −1.6) mmHg; P=0.0014/−1.1 (−3.6, 1.5) mmHg; P=0.3993. Treatment-emergent adverse events (none serious) occurred in 40% of participants.
Conclusions: Switching from SXB to LXB reduced daily medication-related sodium intake in PwN and was associated with clinically meaningful office and ambulatory BP reductions.
Short Description: Excess sodium intake increases hypertension/cardiovascular disease risk, already elevated in people with narcolepsy (PwN) at baseline. Switching from high-sodium oxybate to low-sodium oxybate (LXB) in the XYLO study (NCT05869773) reduced mean 24-hour ambulatory systolic blood pressure (SBP) by 4.1 mmHg and mean seated resting ("office") SBP by 9.2 mmHg in PwN. Switching to LXB reduced medication-related sodium intake and was associated with clinically meaningful reductions in blood pressure, consistent with evidence on sodium reduction effects.
Name of Sponsoring Organization(s): Jazz Pharmaceuticals
