Pharmacology.

Pharmacology

Encompasses the study of the effects of drugs, their therapeutic efficacy, and their fate in the body. When the word gained currency in the 1680s, it also included the art of preparing drugs.

Throughout the previous two centuries, physicians and apothecaries had been adding to and modifying the ancient humoral pharmacological principles codified in herbals, practical guides to botanical identification that also assessed the therapeutic value of plants. This format declined after 1640 as pharmacopoeias began to establish standards for drug preparation and dosage and as botanists began to describe plants in nonmedical contexts.

Many of the new pharmacological concepts originated with Paracelsus (ca. 1493– 1541). He argued that disease represents not imbalances among the classic four humors (blood, phlegm, yellow bile, and black bile) but disturbed interactions among their corresponding elements (air, water, fire, and earth) and his tria prima, the saline, mercurial, and sulfurous principles he said resided in all matter, including plants. This permitted him, for example, to correct putative abnormal acid-base balances with antacid and antalkaline drugs.

In contrast to traditional medicines compounded of many ingredients, Paracelsus favored drugs made of single substances. For instance, he introduced metallic mercury, tartar emetic (antimony potassium tartrate), and ether, the latter because, he said, it allayed pain and induced sleep in his experiments with chickens. Although he also described curious treatments, such as a salve he claimed would cure a wound when applied to the weapon that had caused the injury, such magical remedies were widely discussed, but they never gained the widespread professional acceptance accorded his simpler remedies, some of which survived into the nineteenth century.

The chemical approach to therapy helped change pharmacological thinking largely because Paracelsus demonstrated the value of a close alliance between medicine and chemistry through the latter’s value in preparing effective and safe remedies, such as the chemically purified distilled oils he developed. This prompted European universities to include chemistry courses within their medical curricula, beginning at Marburg, where Johannes Hartmann (1568–1631) was appointed professor of chymiatria (chemical medicine) in 1609. However, his curriculum was not all rational chemistry; it also included the preparation of the wound salve and alchemically derived impossibilities such as “potable gold.”

Paracelsus had argued that medical cures were properly assessed by observation, not by reliance on theory alone. Investigators such as Robert Boyle (1627–1691) and Francesco Redi (1626–1697) agreed on the appropriateness of experimental trials of new medicines and on the value of animals for testing new drugs, but such methods were not widely accepted for more than 250 years.

Those who explicitly rejected Paracelsian concepts included Johann Joachim Becher (1635–1682), who substituted three putative earths for the tria prima, and Georg Ernst Stahl (1660–1734) repudiated iatrochemistry altogether. He gave the name phlogiston to Becher’s terra pinguis, an aspect of combustibility, and promoted antiphlogistic remedies to treat fevers, the most common illnesses of the time. Friedrich Hoffman (1660–1742) favored iatromechanical principles predicated on the assumption that motion is the primary principle of life. He argued that drugs should either strengthen weak fibers in the body or relax excessively rigid fibers.

Followers of Paracelsus contributed other new chemical ideas to pharmacology. Johannes Baptista van Helmont (1579–1644) developed the concept of therapeutic gases, primarily carbon dioxide. Franciscus Sylvius (Franz de la Boë, 1614–1672) systematized Paracelsus’s concepts, focusing increased attention on antacid and antalkaline remedies, while Boyle described chemical indicators of acidity and alkalinity. Johann Rudolf Glauber (1604–1670) developed chemical remedies, such as sodium chloride and magnesium sulfate, that fit within humoral, chemical, and antiphlogistic therapeutic frameworks simultaneously, as did Thomas Sydenham’s (1624–1689) stronger—and cheaper—opium preparation. Although most physicians came to recognize the medical value of the new chemicals, they continued to prescribe botanical drugs while slowly rejecting complex polypharmaceuticals from magical and alchemical traditions. Trade with the East and West Indies led to the introduction of exotic new drugs, especially the American products publicized by Nicolas Monardes (1493–1588). However, most American drugs offered nothing more than those ensconced in the humoral and chemical traditions, and only a few entered European herbals and pharmacopoeias. They included ipecac and cinchona (or Peruvian bark), first used for treating malaria (it is now known to contain quinine) and then for virtually all fevers. Guaiac, sassafras, and sarsaparilla were promoted for treating syphilis, which Europeans believed had been imported from the New World and was, therefore, amenable to treatment with drugs from that area, just as Paracelsus believed that German plants were the best remedies for the diseases of German people.