No new drugs for depression are likely in the next decade, even though those such as Prozac work for little more than half of those treated and there have been concerns over their side-effects, say scientists.
Leading psychiatrists, some of whom have been involved in drug development, say criticism of the antidepressants of the Prozac class, called the SSRIs (selective serotonin reuptake inhibitors), is partly responsible for the pharmaceutical industry’s reluctance to invest in new drugs – even though demand is steadily rising.
But the main reason, said Guy Goodwin, professor of psychiatry at Oxford University, is that the the NHS and healthcare providers in other countries do not want to pay the bill for new drugs that will have to go through expensive trials. The antidepressants that GPs currently prescribe work for only about 58% of people, but they are cheap because they are out of patent.
“We are not going to get any more new drugs for depression in the next decade simply because the pharmaceutical industry is not investing in research,” said Goodwin. “It can’t make money on these drugs. It costs approximately $1bn to do all the trials before you launch a new drug.
“There is also a failure of the science. It has to get more understanding of how these things work before they can improve them.”
Andrea Cipriani, an associate professor of psychiatry at Oxford who works on reviews of the evidence of the effects of the drugs, said at a briefing in London that 58% of patients in clinical trials responded to them, while 40% responded to a placebo. A review of the effects in children found that only one of the SSRIs worked: fluoxetine, better known as Prozac.
But, say the experts, the drugs help people cope with the acute stage of depression, when they feel unable to carry out their daily activities. They help them overcome their negative thoughts and give them a more positive outlook. Recovery, however, takes much longer and involves counselling and other therapy.
Prescription rates have steadily climbed in spite of the limited efficacy and reports of side-effects including suicidal thoughts in young people. “The number of prescriptions for antidepressants has risen quite dramatically since the 1990s,” said Glyn Lewis, professor of psychiatric epidemiology at University College London.
The SSRIs were safer than previous antidepressants, so they began to be prescribed in increasing numbers by GPs and the rate was now rising by 6-7% a year, he said. There were 61m prescriptions a year in England last year, compared with 31m a decade earlier in 2005. The bill was £285m in 2015.
It was not about increasing numbers of people getting depressed, he said. “There is a slight increase in men and women of reports of depression, but that’s not the explanation,” he said. “The increase seems to be about people staying on them for longer.” But it was still not entirely clear whether there was over-prescription or under-prescription, he said.
“Only about 20% of people reporting a lot of symptoms are taking antidepressants. Why not the other 80%? They might have tried them in the past and they didn’t work or they had lots of symptoms.” Lewis is now engaged in research to find out what is happening and potentially give guidance to GPs on when to prescribe.
Maintenance therapy – staying on the drugs for nine months or even longer – does prevent relapses and is helpful, say the experts. But many people then found it hard to come off the drugs, Lewis said.
Counselling and in particular cognitive behaviour therapy have been shown to make people well and are recommended by the National Institute for Health and Care Excellence, while antidepressants are only recommended for moderate to severe cases of depression. There can be long waits for treatment, however, which leads GPs to prescribe antidepressants and patients to take them to alleviate the symptoms while they are waiting.
