How are new drugs tested for their effectiveness without involving the placebo effect?

If there are specific testers of a drug, and they have to have no idea of what they are taking or what it aids with in order to avoid the placebo effect - how is this possible?

Wouldn't that mean the testers would have no idea what they are taking in forms of drugs and medication? Isn't that dangerous if they don't know the full precautions before taking medication?

And if they are testers specifically chosen for a disease or illness they commonly experience - wouldn't that be obvious that they are being given medication for that specific illness of disease when they are called upon, even if it isn't said directly?

Or are random drugs administered to volunteer testers in a facility through their food so they have no idea when or what they are taking?

There are many ways to test new drugs. Those in the final stages that are tested on human volunteers are performed using the double-blind method.

Double-blind describes an especially stringent way of conducting an experiment, usually on human subjects, in an attempt to eliminate subjective bias on the part of both experimental subjects and the experimenters. In most cases, double-blind experiments are held to achieve a higher standard of scientific rigor.

In a double-blind experiment, neither the individuals nor the researchers know who belongs to the control group and who belongs to the experimental group. Only after all the data has been recorded (and in some cases, analyzed) do the researchers learn which individuals are which.

Performing an experiment in double-blind fashion is a way to lessen the influence of the prejudices and unintentional physical cues on the results (the PLACEBO EFFECT, observer bias, and experimenter's bias). Random assignment of the subject to the experimental or control group is a critical part of double-blind research design. The key that identifies the subjects and which group they belonged to is kept by a third party and not given to the researchers until the study is over.

Double-blind methods can be applied to any experimental situation where there is the possibility that the results will be affected by conscious or unconscious bias on the part of the experimenter.
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It's an excellent question and I'll try to address it as best I can. Basically it boils down to the inherent statistical beauty of RANDOMIZED, placebo-controlled, double-blinded studies being the gold standard in clinical research. A novel agent would first have to be demonstrated to be safe. After relative safety is rigorously demonstrated, patients with a given disease for which a given drug is intended to treat must be randomized. Randomization of patients into the placebo vs. treatment group ensures that even variables that ARE NOT taken into consideration prior to engaging in the formal study, are inherently controlled for (*this part is critical).

The researchers (or their delegates) only know that all the patients in such a trial have a disease. They simply CANNOT know whether a given patient is receiving the placebo or the agent that's being tested (researcher is blinded). The patient CANNOT know whether s/he is receiving the real agent either (patient is blinded). This double-blinding is critical to ensuring that the researcher cannot influence the results by "selectively" providing a therapeutic agent to patient in whom they "think" it may work better.

This model of clinical research is extremely expensive to conduct and requires a large number of patients participating, but it's genuinely necessary to provide the least biased and most useful information. (Often crossovers are performed mid-way through trials to add even a higher degree of rigour to the study, but that's way beyond the scope of this discussion).

This sort of model for determining the clinical efficacy of novel therapeutic agents is really intended to advance the search for truth as opposed to inherently help test subjects. There's a lot of ethical considerations that have to be met prior to engaging in such trials, and patients are notified, quite explicitly, that they simply have no way of knowing whether they will be in a placebo group or the "test" group.

If, in say, a few months, the results show that the treatment group is doing extraordinarily better than the control group, then the study can be terminated prematurely in an effort to get the new drug out asap.

Essentially, it's the inherent beauty is such a method of investigating a novel agent that is so highly-regarded as it pertains to the scientific method. If a well-performed and controlled study is done, it makes its results very difficult to scrutinize. But nonetheless, such a high degree of rigour often makes it really difficult to show a statistically significant difference between the groups, and many such trials fail to show a significant difference.

And although I really don't have much (if any) love for Big Pharm, to their credit, these studies are often performed in a multi-center manner and cost a tremendous amount of money. A large portion of that cost burden goes into the staggering price of novel medications, regrettably.

But frankly, it's the best way for physicians to know whether they are providing an effective agent to a patient or some rubbish. It's really in everyone's best interest that after an agent is placed on the market that a clinician can confidently prescribe said agent to patients.

I hope that made a bit of sense.