Neurim Pharmaceuticals Ltd provided results of a study evaluating the effects of its insomnia drug Circadin (prolonged-release melatonin) compared to Zolpidem and placebo on postural stability (body sway) in healthy middle-aged volunteers.

Postural instability, also referred to as body sway, increases with age and is considered to be an important risk factor for falls and fracture among hypnotic drug users.

The study objective was to evaluate the effect of Circadin on postural stability in older adults awakened in the middle of the night; 24 healthy volunteers (age 55-64) completed a single-dose, three-way crossover study of postural stability (body sway) after bedtime administration of Circadin 2 mg (melatonin), zolpidem 10 mg, or placebo with 7-10 days of washout between treatments.

Subjects were tested for postural stability 15 minutes before drug administration (at bedtime) and after 1.5 and 4 hours. Subjects were asked to stand on a stabilometric platform with their eyes closed and open. Parameters tested were the area of the 95% confidence ellipse enclosing the Center of Pressure (COP [A95]) and length of the COP path. Adverse events were recorded throughout the study.

No significant differences were found between Circadin and placebo in body sway as measured by the A95 parameter and by the length of the COP, except minor differences at 4 hours under open eyes conditions. Zolpidem, on the other hand, significantly increased body sway as measured by the A95. The results indicate that Circadin does not impair postural stability during mid sleep awakening, while the positive control zolpidem validated the study by significantly increasing postural instability under these conditions.

“This data confirms that Circadin does not raise the risk of falls, which is a major concern with hypnotic drugs use,” said Dr Tali Nir, VP of clinical and regulatory affairs at Neurim Pharmaceuticals. “Our study confirms prior evidence that zolpidem has a negative effect on postural stability that is causally related to the increase in risk of falls and injuries in patients aged 55+ years.”