Cannabis has the potential to bring in a “new era” of medical treatments through the creation of “blockbuster drugs”, according to a leading US physician.

But legalising the plant so that “recreational” users could smoke it without prosecution could damage an entire generation who would be at risk of becoming hooked on the highly addictive plant, Andrea Barthwell claims.

Dr Barthwell, an expert in addiction and a former advisor to President George W Bush, is on the Island to present a seminar to doctors on recent scientific developments in the pharmacology of medical marijuana.

Speaking ahead of yesterday’s presentation, Dr Barthwell told The Royal Gazette that further research and testing needed to be conducted before cannabis-based drugs can become more widely available.

“There’s a lot of potential for medication development in that plant and it’s going to usher in a new era of medication treatment,” Dr Barthwell said.

“We’re going to be able to treat some diseases that before have not been treated and we’re going to have some blockbuster drugs — but it hasn’t matured yet.”

Dr Barthwell pointed out that all US pharmaceuticals have to go through a series of stringent tests before being approved.

“The California government spent a lot of money investing in head-to-head trials with smoked cannabis and other standard therapies and placebo and what they have found is pre-clinical evidence that there is something there,” she said.

“But it is still pre-clinical and pre-clinical data has to be followed up with clinical data.

“I take my role in the care of patients very seriously and if I’m going to make a recommendation of a medicine for a patient, I need a robust body of data to inform my selection of medication. I need information that tells me how the medication works with the symptom and the disease I’m working with, how it may react with other medications that patient might be taking, any side effects, and I need information on quality, safety and efficacy, to know that I am prescribing something that has a good chance of working — better than a placebo. And then I want to make sure that the supply that I have is defined and reproducible and is safe in the population.

“That’s standard procedure for medication. Drug authorities are trained to review the information that a sponsor brings forward. Nobody would argue that a sponsor doesn’t have a skin in the game and they want to get their medication approved. Authorities reviewing it in the US are trained to review that information and then subject it to a peer review — an advisory panel that doesn’t have a conflict of interest with that sponsor and then they review that answer and make their own independent determination. As far as I’m concerned in the US the only individuals who are qualified to review that data and make a recommendation to a physician are people who are specifically trained in that process. Marijuana hasn’t gone under any medicinal review and it can’t quite frankly because there’s no product that a sponsor can bring forward.”

Dr Barthwell said that certain medically beneficial cannabis molecules had already been identified — such as THC — and reproduced synthetically.

“We do know that THC stimulates appetite and there is a medicine, a capsule, that people can now take that is derived from our knowledge of the plant but it was a serendipitous finding.

“If you can harness those molecules and sometimes even modify them — all of these things happen and all of these things are underway with the cannabis plant — we know a lot about the molecules in it.”

Dr Barthwell said that critics of synthetic cannabis-based medicines claimed that capsules were not as effective as inhaling cannabis smoke.

But she said developments were underway that will improve the effectiveness of synthetic drugs.

“Their argument falls apart and is more politically tied to wanting to have access to this controlled substance,” she said of campaigners who want to legalise or decriminalise cannabis.

“When you have something that’s a controlled substance yo have to think about public health consequences of access to it — it’s not like saying ‘use some aloa on your windowsill when you get a burn’. This is a controlled substance and it has consequences with its use.”

According to Dr Barthwell, adolescents who start smoking cannabis fail to mature fully and display typical adolescent traits, such as a rebelliousness, throughout their lives.

“You don’t get maturation into adulthood,” she said.

“Once of the cardinal signs of adolescence is rejecting authority and that persists across the life of those marijuana users.

“I don’t support the legalisation of marijuana because it undermines one of our six major deterrents to youth use. Its illegal status warns off the would-be user that there’s something to be concerned about as you approach that line and it does work.

“There’s a big difference between marijuana and all the other drugs of abuse. Every other drug of abuse — people have a dependence on it and there’s a problem that’s visible to you and others around you.

“With marijuana once you start there’s a very slow trajectory of decline. Those changes aren’t visible to you or people around you, but look back at the end of your life and find that you’ve ended up somewhere other than what your mother might have predicted at 12, and nobody saw it coming — they didn’t know what was responsible for the changes that were occurring slowly in your life.

“It’s hard to see how its affecting them, but from my worldview as a physician, they’ve been extremely affected.

“There are people who want you to believe it’s a cure-all, to make it socially acceptable as part of an overall strategy to legalise all drugs. It’s the camel’s nose under the tent.”