Janssen's Invega approved for schizophrenia

Janssen, a subidiary of Johnson & Johnson, is looking to maintain its position in the schizophrenia therapeutics market with the release of Invega as their older Risperdal (risperidone) franchise is starting to lose patent protection.

The new drug, which combines the new molecular entity (NME) paliperidone, the principal active metabolite of Risperdal with a novel drug delivery system, allows once-daily oral dosing rather than the twice daily dosing required for Risperdal.

Schizophrenia is a disabling mental illness, that effects more than two million Americans, with symptoms including hallucinations, delusions, disordered thinking, movement disorders, social withdrawal and cognitive deficits. The nature of the illness means that the more infrequent the dosing regime the better, as less time needs to be taken by health workers to check for treatment schedule compliance.

Commenting on the latest approval, Douglas Throckmorton, MD, deputy director of FDA's Center for Drug Evaluation and Research, said: "Schizophrenia can be a devastating illness requiring lifelong medication and professional counselling."​

"Today's approval adds to the treatment options for patients with this condition."​

Risperdal is Johnson & Johnson's most important drug, bringing in $3.5bn (€2.7bn) in 2005. Janssen will hope that Invega will add to its Risperdal Consta treatment, a long-lasting injection administered every two weeks, which is due for patent expiry in 2007.

A Datamonitor report predicts that the patent expiry will lead to a loss in revenues of over $1bn in 2008, due to generic sales erosion.

The oral Risperdal treatment came off patent in 2006 but Johnson and Johnson are yet to feel the financial pressure of generic competition with their first nine months' sales of the drug up 18 per cent from $2.6bn in 2005 to $3.1bn in 2006.

Invega uses Alza Corporation's Oros extended delivery system to provide a once-daily oral paliperidone treatment that employs osmosis to provide precise, controlled drug delivery for up to 24 hours.

The Oros system targets specific areas of the gastrointestinal tract, providing more efficient drug absorption and enhanced bioavailability while eliminating the variability of drug absorption and metabolism often caused by gastric pH and motility.

Second-generation antipsychotics have found favour with many clinicians due to their decreased propensity to cause extrapyramidal side effects, which include tremors, slurred speech, anxiety, distress and paranoia.

However, results of two studies, CATIE and CUtLASS 1, looking into the efficacy of atypical antipsychotic drugs found that the second generation drugs are no more effective or tolerable than older drugs.

The market-leading antipsychotic is Eli Lilly's Zyprexa (olanzapine) which had 2005 sales topping $4bn. The New York Times accused Eli Lilly in December 2006 of unethical, and possibly illegal marketing of Zyprexa as well as encouraging off-label prescription to patients with dementia.

Eli Lilly's fourth quarter profits are expected to fall by $500m as a result of its settlement with 18,000 plaintiffs who sued over the side effects of the drug. It has now agreed to pay at least $1.2bn to 25,500 claimants.