There are a lot of drugs involved - more than I would have imagined even existed. Quite possibly they were tested under ad hoc conditions based on medicinal chemistry principles. (Often in drug discovery for legitimate drugs; people make a number of fairly minor modifications to the structure to view effects.) I know for a fact that this approach has been utilized for psychoactive drugs both legitimately and illegitimately. Examples are amphetamine, methamphetamine, and Ritalin (methylphenidate) all of which have an aromatic ring with a an alkyl side chain having a primary or secondary amine in the 2 position.
These examples are all stimulants of course, and would certainly be of use to people on long trips.
Some of the hallucinogenic analogues also exhibit these features. The drug mescaline is an example, where the phenyl ring is substituted with three methoxygroups, and "ecstasy," which is an formyl acetal of dihydroxyamphetamine, "MDA," methylene dioxyamphetamine. In both cases, there is an alkyl side chain with an amine in the 2-position with respect to the aromatic ring.
Similarly, there are different forms of lysergic acid amides. (The diethylamide is LSD). The desalkyl amide of LSD, ergine, is hallucinogenic and was known to native Americans as ololiuhqui; it's a component of morning glory seeds. These moieties are generally derivatives of the amino acid tryptophan, which has a structure containing an indole ring system, as are some of the soporific sleep aids. (I'm an insomniac, and on particularly bad nights I will take zolpidem, (Ambien) which is an isostere of melatonin, the natural sleep inducing OTC compound. This is probably why drinking milk can help one to sleep. Milk is rich in tryptophan. This drug, zolpidem, can be subject to abuse; and as such, I ask my wife to control my access since when I was a "jet setting executive" I began to develop bad habits in using it It can induce a stupor in which one is not aware that one has already taken a dose. I started taking it on trips to Europe to adjust to the time change. There was a point it got out of control. I now use it maybe a few times a month, and in such a way that I know that I have done so.)
The short acting hallucinogen, DMT, dimethyl tryptamine is derived is in this class. So is psilocybin.
The pharmacokinetics of only a small subset of designer drugs are likely to be known, and only in cases where they were subject to human clinical trials. Thus the length of time that they are active is probably not known for most of them.
I would imagine that many, if not all, exhibit rather profound side effects with repeated use and even singular use.
It's a bad idea to take psychoactive compounds and drive; it's generally a bad idea to take psychoactive compounds of any kind under any circumstances if one can avoid it.
This said, a few clinical trials have explored hallucinogens for the treatment of depression. There's some evidence that they are effective in this way, but only for a subset of people. I encouraged my nephew, who is depressive, occasionally suicidal, to register for clinical trials of hallucinogenic isosteres. Happily he found an approved pharmaceutical drug that helps him to manage his depression; he's doing well and so there's no need to explore clinical trials. Our family is relieved; we love that young man.
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