New Uses for Old Drugs

At the end of last year I reported the success of using a muscle relaxant to treat alcohol addiction. As a former ‘new drug developer’ with a pharmaceutical company, I’m always interested in reports like this, showing that careful preclinical research can sometimes be trumped by serendipity. Here’s another example.

A small study last year showed that tamoxifen – an estrogen-receptor antagonist used against breast cancer – was found to be helpful in treating manic symptoms in bipolar patients. Now a double-blind study has been reported in the Archives of General Psychiatry that confirmed these preliminary findings in a more rigid clinical testing protocol; the trial was conducted in Turkey .

Sixty-six patients with manic or mixed symptoms of bipolar disorder were treated with tamoxifen or placebo for up to 3 weeks. Tamoxifen significantly decreased available measures of severity of symptoms of bipolar disease, while the scores were increased slightly in the placebo-treated patients.

It’s been proposed that a common mechanism – protein kinase C inhibition – could be responsible for tamoxifen’s efficacy in two such widely disparate conditions (cancer and bipolar disease). If these findings can be reproduced – and they need to be – they will provide another example of a new use for an old drug.