To understand why, we first need to go through a quirk of the licensing process. Drugs do not simply come on to the market for use in all medical conditions: for any specific use of any drug, in any specific disease, you need a separate marketing authorisation. So a drug might be licensed to treat ovarian cancer, for example, but not breast cancer. That doesn't mean the drug doesn't work in breast cancer. There might well be some evidence that it's great for treating that disease, too, but maybe the company hasn't gone to the trouble and expense of getting a formal marketing authorisation for that specific use. Doctors can still go ahead and prescribe it for breast cancer, if they want, because the drug is available for prescription, it probably works, and there are boxes of it sitting in pharmacies waiting to go out. In this situation, the doctor will be prescribing the drug legally, but "off-label".
Now, it turns out that the use of a drug in children is treated as a separate marketing authorisation from its use in adults. This makes sense in many cases, because children can respond to drugs in very different ways and so research needs to be done in children separately. But getting a licence for a specific use is an arduous business, requiring lots of paperwork and some specific studies. Often, this will be so expensive that companies will not bother to get a licence specifically to market a drug for use in children, because that market is usually much smaller.
So it is not unusual for a drug to be licensed for use in adults but then prescribed for children. Regulators have recognised that this is a problem, so recently they have started to offer incentives for companies to conduct more research and formally seek these licences.
When GlaxoSmithKline applied for a marketing authorisation in children for paroxetine, an extraordinary situation came to light, triggering the longest investigation in the history of UK drugs regulation. Between 1994 and 2002, GSK conducted nine trials of paroxetine in children. The first two failed to show any benefit, but the company made no attempt to inform anyone of this by changing the "drug label" that is sent to all doctors and patients. In fact, after these trials were completed, an internal company management document stated: "It would be commercially unacceptable to include a statement that efficacy had not been demonstrated, as this would undermine the profile of paroxetine." In the year after this secret internal memo, 32,000 prescriptions were issued to children for paroxetine in the UK alone: so, while the company knew the drug didn't work in children, it was in no hurry to tell doctors that, despite knowing that large numbers of children were taking it. More trials were conducted over the coming years – nine in total – and none showed that the drug was effective at treating depression in children.
It gets much worse than that. These children weren't simply receiving a drug that the company knew to be ineffective for them; they were also being exposed to side-effects. This should be self-evident, since any effective treatment will have some side-effects, and doctors factor this in, alongside the benefits (which in this case were nonexistent). But nobody knew how bad these side-effects were, because the company didn't tell doctors, or patients, or even the regulator about the worrying safety data from its trials. This was because of a loophole: you have to tell the regulator only about side-effects reported in studies looking at the specific uses for which the drug has a marketing authorisation. Because the use of paroxetine in children was "off-label", GSK had no legal obligation to tell anyone about what it had found.
People had worried for a long time that paroxetine might increase the risk of suicide, though that is quite a difficult side-effect to detect in an antidepressant. In February 2003, GSK spontaneously sent the MHRA a package of information on the risk of suicide on paroxetine, containing some analyses done in 2002 from adverse-event data in trials the company had held, going back a decade. This analysis showed that there was no increased risk of suicide. But it was misleading: although it was unclear at the time, data from trials in children had been mixed in with data from trials in adults, which had vastly greater numbers of participants. As a result, any sign of increased suicide risk among children on paroxetine had been completely diluted away.
Later in 2003, GSK had a meeting with the MHRA to discuss another issue involving paroxetine. At the end of this meeting, the GSK representatives gave out a briefing document, explaining that the company was planning to apply later that year for a specific marketing authorisation to use paroxetine in children. They mentioned, while handing out the document, that the MHRA might wish to bear in mind a safety concern the company had noted: an increased risk of suicide among children with depression who received paroxetine, compared with those on dummy placebo pills.
This was vitally important side-effect data, being presented, after an astonishing delay, casually, through an entirely inappropriate and unofficial channel. Although the data was given to completely the wrong team, the MHRA staff present at this meeting had the wit to spot that this was an important new problem. A flurry of activity followed: analyses were done, and within one month a letter was sent to all doctors advising them not to prescribe paroxetine to patients under the age of 18.
How is it possible that our systems for getting data from companies are so poor, they can simply withhold vitally important information showing that a drug is not only ineffective, but actively dangerous? Because the regulations contain ridiculous loopholes, and it's dismal to see how GSK cheerfully exploited them: when the investigation was published in 2008, it concluded that what the company had done – withholding important data about safety and effectiveness that doctors and patients clearly needed to see – was plainly unethical, and put children around the world at risk; but our laws are so weak that GSK could not be charged with any crime.
After this episode, the MHRA and EU changed some of their regulations, though not adequately. They created an obligation for companies to hand over safety data for uses of a drug outside its marketing authorisation; but ridiculously, for example, trials conducted outside the EU were still exempt. Some of the trials GSK conducted were published in part, but that is obviously not enough: we already know that if we see only a biased sample of the data, we are misled. But we also need all the data for the more simple reason that we need lots of data: safety signals are often weak, subtle and difficult to detect. In the case of paroxetine, the dangers became apparent only when the adverse events from all of the trials were pooled and analysed together.
That leads us to the second obvious flaw in the current system: the results of these trials are given in secret to the regulator, which then sits and quietly makes a decision. This is the opposite of science, which is reliable only because everyone shows their working, explains how they know that something is effective or safe, shares their methods and results, and allows others to decide if they agree with the way in which the data was processed and analysed. Yet for the safety and efficacy of drugs, we allow it to happen behind closed doors, because drug companies have decided that they want to share their trial results discretely with the regulators. So the most important job in evidence-based medicine is carried out alone and in secret. And regulators are not infallible, as we shall see.
Rosiglitazone was first marketed in 1999. In that first year, Dr John Buse from the University of North Carolina discussed an increased risk of heart problems at a pair of academic meetings. The drug's manufacturer, GSK, made direct contact in an attempt to silence him, then moved on to his head of department. Buse felt pressured to sign various legal documents. To cut a long story short, after wading through documents for several months, in 2007 the US Senate committee on finance released a report describing the treatment of Buse as "intimidation".