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Regulators approve a new treatment
IT HAS BEEN over 30 years since a genuinely new type of drug for treating depression, or indeed any psychiatric illness, has come to market. Most antidepressants to date have been based on the “monoamine hypothesis”, which holds that depression is caused by low levels of a class of chemical messengers (the monoamine neurotransmitters: serotonin, norepinephrine and dopamine) in the brain. Unfortunately, over a third of patients fail to respond to these drugs, and even when the drugs do work, it can take weeks or months for their effects to kick in.
Hence the interest in a recent announcement by the Food and Drug Administration (FDA) in America that it had approved a new drug for patients with “treatment-resistant” depression, defined as having not responded adequately to at least two previous antidepressants. Of particular note is that it is based on ketamine, a recreational drug. Esketamine, as the chemical is known, is branded as Spravato by its developer, Janssen Pharmaceuticals, a branch of Johnson & Johnson.
Widely used as an anaesthetic, ketamine blocks specific chemical receptors, especially one for glutamate, the most abundant chemical messenger in the brain. Animal research in the 1990s implicated glutamate in depression. A small clinical trial in 2000 showed that not only did ketamine have antidepressant effects in humans, but it took hold within hours. Subsequent studies showed it worked on treatment-resistant depression.
The main side-effect of ketamine is that it has hallucinogenic effects, such as out-of-body or “dissociative” experiences. There is some evidence suggesting the side-effects of esketamine, although similar, are slightly less severe. Nevertheless, the potential for abuse, together with elevated blood pressure and the dangers of wandering around in such a state, are why the FDA has recommended a strict treatment strategy. This stipulates that the drug is administered under supervision, in a clinic or a doctor’s office. Patients should be monitored for at least two hours before they leave, record their experiences and not drive that day.
In research and in clinics that give ketamine to patients able to pay around $3,000, the drug is administered intravenously. The new treatment is taken in the form of a nasal spray. Janssen says the cost of a one-month course will be between $4,720 and $6,785. Previous studies of generic ketamine suggest the effects of multiple doses last a few weeks, on average, but as long as a few months in some people.
The trial data Janssen submitted to the FDA was somewhat mixed, but the agency would probably have taken into account the wealth of information that already existed on ketamine’s effectiveness, says Carlos Zarate of the National Institute of Mental Health. That includes a trial he led, published in 2006. One of ketamine’s remarkable properties, says Dr Zarate, is that it has a “broad spectrum” effect, alleviating many of the different mood symptoms that can occur in depression, including anxiety and the inability to experience pleasure. For patients at acute risk of suicide, for which drugs can take too long to work, there is evidence that it might be a lifesaver by reducing suicidal thoughts.