Whereas the science of curative substances, which originally came from plant parts such as leaves and roots, developed over the whole course of human history, pharmaceutical research in the area of formulations is less than 120 years old. During this time, chemists and apothecaries have repeatedly found new ways to deliver active ingredients to their targets.

As long as this knowledge was missing, drugs were prescribed fairly nonspecifically. As a result, on their journey through the body they often lost much of their effectiveness and in many cases caused unwanted side effects. Some 2,400 years ago, the ancient Greek physician Hippocrates advised pregnant women to chew willow bark in order to mitigate their labor pains before giving birth. He didn’t know that the cause of the analgesic effect was the salicylic acid salts contained in the bark. Nor did he know about the side effects of these salts. Even in 1874, when salicylic acid was first produced on an industrial scale, it was a double-edged sword for the patients who used it. Their original symptoms disappeared—but the patients then complained of stomachaches.

Jakob Hoffmann, a merchant in Ludwigsburg, was not satisfied with this outcome. He challenged his son Felix, an up-and-coming chemist, to find out the cause of the problem. At the time, Felix was working in the scientific laboratory of the pharmaceutical company Farbenfabriken vorm. Friedr. Bayer & Co. in Wuppertal- Elberfeld. He went to work immediately. The experiment in which he reacted salicylic acid with acetic acid finally yielded the desired result: acetylsalicylic acid. Hoffmann produced this substance synthetically for the first time on August 10, 1897. Under the brand name Aspirin, acetylsalicylic acid became one of the bestknown medications of the modern era. Aspirin was initially sold in bags in powder form, but in 1900 Bayer launched this active ingredient on the market in the form of tablets containing 500 mg of acetylsalicylic acid.

Orally administered active ingredients were initially simply pressed into tablets, but the producers soon realized that the tablets would be more durable and effective if they had a protective coating. Apothecaries would traditionally coat the tablets with a thick coating of sugar. These dragées often also contained pigments such as titanium dioxide that would block the ultraviolet radiation of sunlight. As a result, the active ingredients would not disintegrate into undesirable decomposition products, even if they were stored for a long period of time.

On a drug’s journey through the body, the gastrointestinal tract is the first major barrier. From here, the active ingredient must find its way into the bloodstream so that it can be transported into the diseased tissue. “Resorption” is the term used by pharmacists for the passage of the active pharmaceutical ingredient through the cells of the intestinal wall. But before the substance reaches the small intestine, it must first pass through the very acidic environment within the stomach. It can do this successfully if it is covered with a film of polymethacrylate. A layer that is only 50 micrometers thick is sufficient to resist the gastric fluids.

The chemist Otto Röhm Jr. was the first one to recognize the pharmaceutical significance of this plastic. Röhm’s father is still well-known as the inventor of Plexiglas. He applied for a trademark for it in 1933. Two decades later, his son launched pharmaceutical film coatings under the brand name EUDRAGIT on the market. Incidentally, the company he worked for is now part of Evonik. EUDRAGIT has a crucial advantage over traditional sugar coatings: Whereas sugar coatings can double the weight of a tablet, a film coating of EUDRAGIT only increases the weight by about three percent.

Ever since then, this material has developed into a versatile technology platform. Today it can be used to combine the different attributes of medications by means of a modular system. For example, active ingredients can be precisely released in a certain section of the small intestine. This is made possible by the fact that the polymethacrylates used for this purpose do not dissolve in acidic environments, but rather in the neutral environment of the intestine.

The pH of an aqueous medium indicates how acidic it is. In an empty stomach with high acidity, the pH value is between 1 and 2. By contrast, in the small intestine the pH value is initially 5.5 and gradually increases to as much as 7. If the solubility of the polymethacrylate film is set at a pH value of 7, the active ingredient is not released until the passage between the small and large intestines. This is medically useful in cases such as the local treatment of inflammatory intestinal diseases.