Glad it helps. Actually, many more layers of separation than you imagine for clinical trials. (And many variations on how randomization is achieved). Most trials have dozens of independent locations that have little to connection with each other. Typically, the pharmaceutical company contracts with a 'clinical research organization' (CRO) to coordinate it all. The CRO usually uses a separate system and/or company to perform randomization. And the whole thing is potentially monitored by yet another separate agency and subject to legal scrutiny and penalties for wrongdoing by the FDA. You can find more deets at clinicaltrials.gov. have fun 👍

How it actually works for most studies for meds. We get shipped a bunch of identical boxes - identical except some contain placebo, some investigational product. After the potential subject passes the screening process (to ensure they are a good candidate and meet all inclusion criteria), we log into a program that gives us the code number for the box to give the subject. The distribution of numbers is predetermined. No one really knows what is distributed.

FWIW, fraud - if it exists - has nothing to do with the desired outcome. It is the result of the financial motivation to enroll subjects, which can be significant. Most of the unsavory activity is from greedy sites enrolling unqualified or even phony people.

You are actually asking 2 questions. The frequency of dosing for effect, and maximum dosing to avoid problems. The labeling for the latter is not based solely on pharmacokinetic data. Rather, a mix of data, opinion and (at least in the US) the FDA's assumption that all users are dumb as a bag of hammers.

Also depends on the nature of the chemical and the desired results, and how anxious the developers want to bring it to market. For example, certain compounds are easy to inject, but developing an oral formulation (which are generally more desirable) would take longer. But if the drug is the first drug in a new class, the first to market status could trump oral availability.

Also, sometimes drugs are for specific applications - there is no point in testing a topical agent orally. Or the rectal absorption of a drug intended for join injections.

But sometimes it happens that a smart person thinks "hey, this drug I've been injecting could work on hemorrhoids." So then that might be studied.