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2.2.1 Clinical Trials
Clinical trials are medical studies statistically designed to assess the safety and efficacy
of a new treatment -drug, device, psychological therapy, etc- for and with humans.
From now on, we will focus on clinical trials testing new drugs and use the word
drug and treatment interchangeably. Clinical trials are also performed in order to
“extend the label” of an already marketed drug, that is, to prove more benefits to
its consumers or to expand the range of diseases for which the drug has a positive
effect. A clinical trial is the last step of a long chain in the development of a new
treatment; potential drugs have to be discovered, purified, characterized, and tested
in labs before proceeding with a clinical trial.
Clinical trials involve human beings as experimental units and, thereby, a number
of ethical considerations must be taken into account. Among other controls, at each
participating institution an Institutional Review Board must approve and supervise
these studies. In order to include a patient in the study, the researcher must get
informed consent from the patient, that is, the participants must be aware of the
risks involved in the trial. Besides, the participant has the right to withdraw from
the trial at any moment. The eligibility of patients must be restricted. For example,
pregnant women or patients with better medical options than the tested treatment
are usually not allowed to enroll.
Clinical trials for drugs are classified according to their specific objective in four
different kinds: phases I, II, III and IV. A new drug must successfully pass the first
three phase trials before reaching the market. Phase IV trials are post-marketing
studies. Next we briefly describe the different types of clinical trials.
Phase I trials have the objective of finding the acceptable or safe dosage of the new
drug. A small number of, generally healthy, patients (20 to 50) are enrolled and
followed very closed. The participants do not expect any health benefit. The
study involves escalation of the doses before an intolerable level of toxicity is
identified.