The long-term effect of ketamine is not yet understood, but establishing safety and effectiveness in these very small trials is the first step.
saying it is more dangerous than heroin is pretty dubious don't you think? Do you have any evidence better than this: http://en.wikipedia.org/wiki/File:Rational_scale_to_assess_t... ?
- The rankings are creating by combining a lot of different factors that don't have anything to do with each other, e.g. by combining harm to the user with harm to society. This means that drugs like coffee end up being more dangerous than drugs like heroin, simply because more people use coffee than heroin so the total social costs are greater.
- The harms for drugs are measured as they are typically used, rather than correcting for things like differences in demographic and route of administration. This leads to drugs like heroin looking more dangerous than they are, because people who have drug abuse problems tend to gravitate toward drugs like heroin. (Whereas people who use, say, Khat tend not to be the worst of the worst as drug abusers go.)
- The harms of the drugs caused by prohibition are not accounted for. (E.g. they are counting people using dirty needles and impure/unknown/fake drugs as being a harm that stems from heroin, but they aren't counting using dirty needles and fake Starbucks as being a harm that stems from drinking coffee.)
- They're not accounting for the benefits of drug use, only the harms.
I could keep going, but I think I've sufficiently proven my point and then some.
Whereas opiates, to my knowledge, don't actually have any serious side effects, or long term health issues (apart from constipation and perhaps lowered testosterone). Apart from the overdose risk, that is.
The brain damage effect is uncharacterized in humans. Several NMDA drugs cause this effect in rats, but none of them have been found to cause devastating problems in humans except PCP.
There is some suggestion that opioids cause cancer, but the only study was small and observational.