Minerals, such as calcium, magnesium, and silver salts in several forms, are used in some pharmacological agents. For example, Tums and Mylanta are antacids that contain calcium (Tums) and magnesium (Mylanta) hydroxides. Silver sulfadiazine (Silvadene cream) is an antimicrobial agent used in dressings for burn patients that contains silver salts (see Chapter 5). Even gold is used, as in aurothioglucose (Solganal), an anti-arthritic agent.

The second major source of drugs is chemical synthesis in the laboratory (Fig. 1-2). There are two ways for drugs to be synthesized, that is, put together. Synthetic drugs are drugs that are synthesized from laboratory chemicals. Semisynthetic drugs are drugs that start with a natural substance that is extracted, purified, and altered by chemical processes. The vast majority of modern drugs are either synthetic or semisynthetic. Meperidine (Demerol) is an example of a synthetic drug; it is made from chemicals, yet its pain-relieving effects are similar to those of opium. Many types of penicillin, such as amoxicillin, are semisynthetic drugs. The penicillin group of drugs was originally derived from a natural mold (Penicillium), the active substance of which is extracted and purified in the chemical laboratory. Another example of semisynthetic drugs is the aminoglycoside group of antibiotics, the active substance of which is obtained from the bacterial species Streptomyces.