Eli Lilly says that regulators in the USA have given the green light to a long-lasting injectable version of its antipsychotic blockbuster Zyprexa.

The US Food and Drug Administration has approved Zyprexa Relprevv (olanzapine) for the treatment of schizophrenia in adults. The latter is a long-acting intramuscular injection which sustains the delivery of the drug for up to four weeks< Lilly said. The approval is based on a data package involving 2,054 patients, in which Zyprexa Relprevv was found to be effective in controlling symptoms of schizophrenia, including hallucinations, delusions, apathy and social withdrawal.

Lilly also noted that efficacy was shown without the need for oral supplementation, the way Zyprexa is normally administered as a once-daily pill. The company quoted John Kane, chairman,of the Department of Psychiatry at Zucker Hillside Hospital, New York, as saying that “patients, families and communities often needlessly suffer the consequences of relapse when daily schizophrenia medications are not taken as prescribed".

Lilly adds that by administering long-acting medications, psychiatrists know when patients have received their medication and can immediately detect non-adherence when a patient does not return for a scheduled injection. The company has also satisfied the FDA’s concerns, expressed in a complete response letter issued at the beginning of the year, by developing a risk evaluation and mitigation strategy, plus a patient care programme.

Analysts have predicted annual sales for the long-acting formulation, which was approved in December 2008 in Europe under the brand name Zypadhera of around $125 million by 2011, when the basic form comes off-patent.