After surveying 25 neurologists who currently prescribe Supernus Pharmaceuticals' Oxtellar XR in epilepsy, Piper Jaffray analyst David Amsellem believes the eventual label expansion for the drug as monotherapy for partial seizures, expected before year-end, is unlikely to drive a major uptick in prescription volume growth. Notably, a significant majority of respondents to the survey already use Oxtellar XR as monotherapy, Amsellem tells investors in a research note. The analyst continues to caution against drawing parallels between the Oxtellar XR monotherapy opportunity and Trokendi XR in migraine prophylaxis. Amsellem does not believe the current risk/reward profile is favorable on Supernus shares and keeps a Neutral rating on the name with a $44 price target.