Children with depression who did not respond to pills have finally seen results after receiving an IV drip of ketamine, according to a new study.

Thirteen teenagers aged 12 to 18 received infusions of the illegal drug, which was first created as a horse tranquilizer, over the course of two weeks.

By the end, five of them (38 percent) were deemed to be in remission.

The authors of the study, done by the University of Michigan, say it is proof that ketamine can be safely administered to children - a question that researchers have been racing to answer as the drug gains traction as a more effective alternative to antidepressants.

Recently, ketamine has gained traction as an alternative to antidepressants

Ketamine's rise has come amid a soaring demand for alternative to antidepressants.

The rate of children and teenagers diagnosed with depression is steadily climbing year on year. Most are prescribed SSRIs, highly addictive antidepressants, which carry excruciating side effects when coming off them.

However, around 40 percent of teenagers do not respond to the first type of drug their doctor suggests to try, so they have to try another one. And if that doesn't work, they try another - and so on, until they find their Goldilocks pill.

In theory, these drugs are to be used as a short-term measure as patients work towards remission, rather than spending a lifetime on medication.

However, studies show that the thousands of patients who go through this cycle of trial and error are far less likely to ever achieve remission.

Although ketamine itself can be addictive, the idea of administering small doses of it in transfusions is in vogue in mental health research at the moment - partly because it works so quickly.

The drug activates the part of the brain that regulates emotions, and promotes neural plasticity - the ability of the brain to change and adapt in response to experience.

What's more, it works much faster than SSRIs, and appears to last longer to move congestion in the brain that may be hampering the patient's freedom of thought and feeling.

It's widely agreed that patients with depression appear to have dampened connections between certain neurons, caused by a build-up of proteins on top of cell membranes.

In healthy brains, cell membranes are free and open to receive signals. In patients with depression, an overwhelming amount of G proteins pile up on top of lipid rafts - kind of like lids which sit on top of cell membranes.

This pile-up prevents free movement.

SSRIs help to shift these G proteins off the lipid rafts, unblocking congestion, within about an hour.

Ketamine does the same, but in 15 minutes - and studies have found the effects to last much longer.

'The field is excited about a potential new agent for adolescents with treatment resistant depression. We look forward to additional studies of ketamine to validate this treatment,' says Dr Harold S. Koplewicz, Editor in Chief of the Journal of Child and Adolescent Psychopharmacology, which published the study on Wednesday.