* To apply for U.S. marketing approval in the third quarter
* Drug reduced severity of schizophrenia symptoms in trial
* Shares rise as much as 11 pct (Adds analyst comment; updates share movement)
By Vrinda Manocha
April 8 (Reuters) - Alkermes Plc said it planned to seek U.S. marketing approval for its experimental drug to treat the symptoms of schizophrenia after it succeeded in a late-stage study, sending the company's shares up as much as 11 percent.
The company said it would apply for marketing approval for a monthly dose of the injectable drug, aripiprazole lauroxil, in the third quarter of 2014.
"Once monthly or even less frequent dosing is key, since it increases compliance rates in schizophrenia, reduces relapse rates and hospitalization costs and provides costs savings to the healthcare system," Leerink Partners analyst Michael Schmidt said in an e-mail.
He expects U.S. approval for the drug in the third quarter of 2015.
Data from the late-stage study supported dosing of the drug once every two months, Chief Executive Richard Pops said on a conference call with analysts.
The drug is a long-acting atypical antipsychotic, a class of drugs with fewer side effects than older antipsychotics.
The growing market for atypical antipsychotics for schizophrenia was worth $4.5 billion in the United States, Pops said. He said the company would launch aripiprazole lauroxil using its own sales force.
"We now have multiple doses with established efficacy that may help physicians to address the specific needs of individual patients," Alkermes' Chief Medical Officer Elliot Ehrich said.
The company said two doses of the drug injected monthly reduced the severity of schizophrenia symptoms in the study, compared with a placebo.
Once inside the body, Alkermes' drug converts into aripiprazole, a blockbuster marketed as Abilify by Otsuka Pharmaceutical Co Ltd.
Alkermes' technology allows the drug to be released at a controlled rate in the body, allowing patients to take the drug less frequently.
Eli Lilly and Co's antipsychotic injection Zyprexa Relprevv is approved to treat schizophrenia and is administered once in two-four weeks, depending on the dose. Otsuka's injection Abilify Maintena is dosed once a month.
Alkermes receives royalty payments from a Johnson & Johnson unit for two atypical antipsychotic injections, Risperdal Consta and Invega Sustenna, which use its technology.
The company is also developing the Invega Sustenna as a schizophrenia treatment to be dosed once in three months.
The company said on Tuesday the drug was generally well tolerated by the 623 patients enrolled in the study. The most common adverse events were insomnia, headache and akathisia, a condition characterized by uncontrollable restlessness.
Alkermes said all participants in the study were eligible to continue in treatment for 12 months to monitor the safety and long-term durability of the treatment.
Schizophrenia, which is characterized by distorted thoughts, hallucinations and paranoia, affects about 24 million people worldwide, according to the World Health Organization.
The Dublin, Ireland-based company's shares were up 2.7 percent at $42.23 on the Nasdaq on Tuesday. They rose to $45.48 earlier in the session.
(Reporting by Vrinda Manocha in Bangalore; Editing by Savio D'Souza and Don Sebastian)