A century ago, when a physician prescribed, for instance, tincture of opium, he had no way of knowing how much opium his patient would receive save by referring him to some druggist with whose preparations the physician had had previous experience. The evils of this confusion were so apparent that the country had hardly achieved political independence before the medical profession began to agitate for some means of providing uniformity in the materia medica. This agitation culminated in 1820 in the first publication of the first U. S. Pharmacopeia.
Although this work consisted merely of a list of crude drugs with formulas for preparing from them various galenicals, it represented an effort to reach at least an approximate agreement throughout the country in the activity of the commonly used remedies. The sixth revision of the Pharmacopeia, published in 1882, marked another great epoch in the progress toward exactitude in therapeutics,
WOOD HC. THE PURPOSE AND LIMITATIONS OF BIO-ASSAY. JAMA. 1912;LIX(16):1433-1435. doi:10.1001/jama.1912.04270100201006