Drugs are discovered, manufactured, and tested by scientific methods. On the other hand they are produced and marketed through a blend of personal and social motives; they are prescribed by doctors with varying knowledges and skills, and they are taken by patients who have different degrees of information, interest, and precision. Drugs are brewed in the cup of science; they are drunk through a patient's lips, and "there's many a slip twixt the cup and the lip." Scientific attention is usually turned toward the discovery of drugs; in the present paper I shall consider the path from their development to their use. As an example, let us take chlortetracycline, one of the first antibiotics to be produced by a pharmaceutical company. After screening hundreds of specimens of soil, Duggar isolated Streptomyces aureofaciens, in the fall of 1945. Its in vitro antibacterial activity was demonstrated later in the same year. Preparation