Stroke, drug candidate

For neuropharmaceuticals that target the brain, as in the cases of neurodegenerative disorders (Alzheimer s, multiple sclerosis),psychiatric or psychotherapy, stroke, and infectious diseases, drug candidates are tested using in vivo and in vitro models to assess the transfer of the drug compound across the BBB. 

Assessing the effectiveness of a new drug candidate can be complex and often difficult. This is because some diseases or symptoms do not follow a predictable path. For example, acute conditions such as influenza or insomnia may resolve without intervention, while chronic conditions such as multiple sclerosis or arthritis follow a varying course of progression. Depending on age, treatment, and other risk factors, heart attacks and strokes may produce variable mortality rates. Additional difficulty is introduced by subjective evaluation, which can be influenced by the expectations of patients and physicians. Some of these issues can be addressed in controlled clinical trials. 

For a new beta-blocker, you would need 40,000 people in a two-year trial, to be extended for eight years, to examine whether your new candidate drug changes the occurrence of cardiovascular incidents like heart attack and stroke. This is the equivalent of a 400,000-man-year trial. This would be a huge trial. If this is not enough to dissuade a pharmaceutical company, consider also that these four successive groups of 40,000 must all not be taking beta-blockers or must be taken off them... 

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