** Shares of drug developer Ovid Therapeutics OVID.O rise 20% to $1.97 premarket

** Co says its experimental epilepsy drug, OV329, showed strong signs of effectiveness in early-stage trial

** The drug is being developed to treat drug-resistant forms of epilepsy, a type of seizure that affects only one side of the brain and body

** The study showed OV329 helped raise levels of a calming chemical in the brain by blocking an enzyme that breaks it down, which may help reduce seizures, co says

** Ovid said OV329 worked as well as or better than vigabatrin, an older medicine used to treat seizures

** As of last close, stock was up 75% YTD

(Reporting by Kamal Choudhury in Bengaluru)

((Kamal.Choudhury@thomsonreuters.com;))