Pharmaceutical industry, the discovery, development, and manufacture of drugs and medications (pharmaceuticals) by public and private organizations.
The following sections provide a detailed explanation of the progression of drug discovery and development throughout history, the process of drug development in the modern pharmaceutical industry, and the procedures that are followed to ensure the production of safe drugs. For further information about drugs, see drug. For a comprehensive description about the practice of medicine and the role of drug research in the health care industry, see medicine.
History
The origin of medicines
- Medicines of ancient civilizations
- Pharmaceutical science in the 16th and 17th centuries
In London the Society of Apothecaries (pharmacists) was founded in 1617. This marked the emergence of pharmacy as a distinct and separate entity. The separation of apothecaries from grocers was authorized by King James I, who also mandated that only a member of the society could keep an apothecary’s shop and make or sell pharmaceutical preparations. In 1841 the Pharmaceutical Society of Great Britain was founded. This society oversaw the education and training of pharmacists to assure a scientific basis for the profession. Today professional societies around the world play a prominent role in supervising the education and practice of their members.
In 1783 the English physician and botanist William Withering published his famous monograph on the use of digitalis (an extract from the flowering purple foxglove, Digitalis purpurea). His book, An Account of the Foxglove and Some of Its Medicinal Uses: With Practical Remarks on Dropsy and Other Diseases, described in detail the use of digitalis preparations and included suggestions as to how their toxicity might be reduced. Plants containing digitalis-like compounds had been employed by ancient Egyptians thousands of years earlier, but their use had been erratic. Withering believed that the primary action of digitalis was on the kidney, thereby preventing dropsy (edema). Later, when it was discovered that water was transported in the circulation with blood, it was found that the primary action of digitalis was to improve cardiac performance, with the reduction in edema resulting from improved cardiovascular function. Nevertheless, the observations in Withering’s monograph led to a more rational and scientifically based use of digitalis and eventually other drugs.
Isolation and synthesis of compounds
In the 1800s many important compounds were isolated from plants for the first time. About 1804 the active ingredient, morphine, was isolated from opium. In 1820 quinine (malaria treatment) was isolated from cinchona bark and colchicine (gout treatment) from autumn crocus. In 1833 atropine (variety of uses) was purified from Atropa belladonna, and in 1860 cocaine (local anesthetic) was isolated from coca leaves. Isolation and purification of these medicinal compounds was of tremendous importance for several reasons. First, accurate doses of the drugs could be administered, something that had not been possible previously because the plants contained unknown and variable amounts of the active drug. Second, toxic effects due to impurities in the plant products could be eliminated if only the pure active ingredients were used. Finally, knowledge of the chemical structure of pure drugs enabled laboratory synthesis of many structurally related compounds and the development of valuable drugs.Pain relief has been an important goal of medicine development for millennia. Prior to the mid-19th century, surgeons took great pride in the speed with which they could complete a surgical procedure. Faster surgery meant that the patient would undergo the excruciating pain for shorter periods of time. In 1842 ether was first employed as an anesthetic during surgery, and chloroform followed soon after in 1847. These agents revolutionized the practice of surgery. After their introduction, careful attention could be paid to prevention of tissue damage, and longer and more-complex surgical procedures could be carried out more safely. Although both ether and chloroform were employed in anesthesia for more than a century, their current use is severely limited by their side effects; ether is very flammable and explosive and chloroform may cause severe liver toxicity in some patients. However, because pharmaceutical chemists knew the chemical structures of these two anesthetics, they were able to synthesize newer anesthetics, which have many chemical similarities with ether and chloroform but do not burn or cause liver toxicity.
The development of anti-infective agents
- Discovery of antiseptics and vaccines
Lister, Joseph
Joseph Lister.
National Library of Medicine
In the prevention of infectious diseases, an even more important innovation took place near the beginning of the 19th century with the introduction of smallpox vaccine. In the late 1790s the English surgeon Edward Jenner observed that milkmaids who had been infected with the relatively benign cowpox virus were protected against the much more deadly smallpox. After this observation he developed an immunization procedure based on the use of crude material from the cowpox lesions. This success was followed in 1885 by the development of rabies vaccine by the French chemist and microbiologist Louis Pasteur. Widespread vaccination programs have dramatically reduced the incidence of many infectious diseases that once were common. Indeed, vaccination programs have eliminated smallpox infections. The virus no longer exists in the wild, and, unless it is reintroduced from caches of smallpox virus held in laboratories in the United States and Russia, smallpox will no longer occur in humans. A similar effort is under way with widespread polio vaccinations; however, it remains unknown whether the vaccines will eliminate polio as a human disease.- Improvement in drug administration
Drug development in the 19th and 20th centuries
- New classes of pharmaceuticals
- Transitions in drug discovery
Obstacles In Drug Development
- Adverse reactions
The fetus is also susceptible to the toxic effects of drugs that cross the placental barrier from the pregnant mother. Body organs begin to develop during the first three months of pregnancy (first trimester). Some drugs will cause teratogenicity in the fetus if they are administered to the mother during this period. Drugs given to the mother during the second and third trimester can also affect the fetus by altering the function of normally formed organs or tissues. Fortunately, very few drugs cause teratogenicity in humans, and many of those that do are detected in animal teratology studies during drug development. However, animal teratogenicity screens are not perfect predictors of all human effects, so there remains some potential of drug-induced birth defects.
Dose-independent adverse reactions are less common than dose-dependent ones. They are generally caused by allergic reactions to the drug or in some cases to other ingredients present in the dosage form. They occur in patients who were sensitized by a previous exposure to the drug or to another chemical with cross-antigenicity to the drug. Dose-independent adverse reactions can range from mild rhinitis or dermatitis to life-threatening respiratory difficulties, blood abnormalities, or liver dysfunction.
- Postmarketing adverse drug events
Identifying adverse drug events is not always easy or straightforward. For example, the FDA may receive a few reports of fever or hepatitis (liver inflammation) associated with use of a new drug. Both fever and hepatitis can occur in the absence of any drug. If either occurs at the same time someone is taking a new drug, it is not always easy or even possible to say whether the event was caused by the drug. There are established procedures that can help determine whether the adverse event is related in a cause-and-effect manner with the drug use. If one stops taking the drug and the adverse event disappears, this suggests the event may be related to use of the drug. If the adverse event reappears when the drug is re-administered, this provides even more evidence that the two events are related. However, for serious adverse events, it is often not advisable to reintroduce a drug suspected of causing the event. Because of difficulties in associating adverse events with a causative agent, these drug-induced adverse events sometimes go unrecognized for a long period of time. There have been instances when pharmaceutical manufacturers and the FDA have been criticized for failing to warn the public about an adverse drug event early enough. In some circumstances the manufacturer and the FDA had suspected that an adverse event might be caused by a drug, but they did not have sufficient data to connect the drug and the event with reasonable accuracy. This issue can be particularly difficult if the drug in question helps severely ill patients, since premature or incorrect reporting of an adverse event may result in a drug being withheld from patients who are in great need of treatment.
- Drug interactions
Interactions during drug absorption may lower the amount of drug absorbed and decrease therapeutic effectiveness. One such interaction occurs when the antibiotic tetracycline is taken along with substances such as milk or antacids, which contain calcium, magnesium, or aluminum ions. These metal ions bind with tetracycline and produce an insoluble product that is very poorly absorbed from the gastrointestinal tract. In addition, drug interactions may affect drug distribution, which is determined largely by protein binding. Many drugs are bound to proteins in the blood. If two drugs bind to the same or adjacent sites on the proteins, they can alter the distribution of each other within the body.
Interactions of drugs during drug metabolism can alter the activation or inactivation of many drugs. One drug can decrease the metabolism of a second drug by inhibiting metabolic enzymes. If metabolism of a drug is inhibited, it will remain longer in the body, so that its concentration will increase if it continues to be taken. Some drugs can increase the formation of enzymes that metabolize other drugs. Increasing the metabolism of a drug can decrease its body concentration and its therapeutic effect. Drugs can also interact by binding to the same receptor. Two agonists or two antagonists would intensify each other’s actions, whereas an agonist and an antagonist would tend to diminish each other’s pharmacological effects. In some interactions, drugs may produce biochemical changes that alter the sensitivity to toxicities produced by other drugs. For example, thiazide diuretics can cause a gradual decrease in body potassium, which in turn may increase the toxicity of cardiac drugs like digitalis. Finally, in the case of drugs excreted by the kidney, one drug may alter kidney function in such a manner that the excretion of another drug is increased or decreased.
While it is important to recognize that drug interactions can cause many adverse effects, it is also important to point out that there are a number of therapeutically beneficial drug interactions. For example, thiazide diuretics (which cause potassium loss) can interact with other diuretics that cause potassium retention in such a way that the combination has no significant impact on body potassium. Cancer chemotherapeutic agents are often given in combination because cellular interactions (such as inhibiting cell replication and promoting apoptosis) among the drugs cause more cancer cell death. Antihypertensive drugs are often given in combination because some of the side effects produced by one drug are overcome by the actions of the other. These are just a few of the many examples of beneficial drug interactions.
- Drug patents
Most governments grant patents to pharmaceutical firms. The patent allows the firm to be the only company to market the drug in the country issuing the patent. During the life of the patent, the patented drug will have no direct market competition. This allows the pharmaceutical company to charge higher prices for the product so that it can recover the cost of developing the drug. Virtually all drugs have brand names created by the companies that develop them. All drugs also have generic names. After the patent has expired, other companies may market the drug under its generic name or under another brand name. In addition, the price of the patented drug usually decreases when a patent expires because of competition from other companies that begin marketing a generic version of the drug. The cost of developing a generic version of a drug for market is significantly less than the cost of developing the patented drug, since many of the studies required for first regulatory approval of a drug are not required for marketing approval for subsequent generic versions. Essentially, the only requirement is to demonstrate that the new version is biologically equivalent to the already approved drug. Bioequivalent drug products have the same rate and extent of absorption and produce the same blood concentration of drug when the two drugs are given in the same dose and in the same dosage form.
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