Here it is http://2x Helps Stop Snoring Throat Spray 9ml https://www.amazon.co.uk/dp/B00VGQWXAW/ref=cm_sw_r_cp_apa_i_FqEUDbV7FH73G
This is the only study that I found. Lower partner-reported snoring than with placebo.
But there's a problem with those data: a few change a lot and most don't change much. The statistical analysis used doesn't handle that adequately.
Apart from that paper that type of intervention isn't discussed in any of the big reviews.