Pharmacology

What is pharmacology?

From helping cure a headache to lowering blood pressure to prevent heart disease, medications are an important part of everyday life. Pharmacology is the study of these medications and how they affect the people who take them for treatment or to manage a disease or condition. The field includes the study of a variety of drugs, from over-the-counter medications and those available only with a prescription from a healthcare provider, to dietary and herbal supplements.

Pharmacology is tied closely to similar fields. Pharmacokinetics, for example, is the study of drug absorption, distribution, metabolism, and elimination. For a medication to be effective, the appropriate amount must be given. The medication must also reach its effective target. To do this, interactions need to occur between the medication and the body. The process of pharmacodynamics explains how the medication affects the body.

A recent field of study, pharmacogenetics, evaluates how someone’s body will respond to certain drugs based on her/his genes. A person’s genes determine the makeup of the body’s proteins. As drugs travel through the body, they interact with these proteins. Because everyone’s genes are different, even if in some cases only slightly different, each person will respond in unique ways to medications. Pharmacogenetics helps determine how much or what type of medication people will need based on their genetic makeup. This field is also called personalized medicine.¹

According to a survey by the Centers for Disease Control and Prevention (CDC) conducted in 2008, at that time almost 50% of Americans had used at least one prescription drug in the past month.¹ A higher percentage of Americans, however, had used over-the-counter medications and dietary and herbal supplements at least once in that time frame. Pharmacology provides the studies to determine the safety and effectiveness of these medications.

Studies of Side Effects and Effectiveness in Different Populations

While the safety of medications is important for everyone, certain groups are at particular risk of adverse reactions. Researchers are studying the reasons behind drug reactions and looking for ways to personalize treatment according to people’s genetic make-up. Among the groups at greater risk for medication problems are the following:

Seniors

Seniors often take multiple medications that may interact with each other and lessen the effects of the drugs or, worse, cause serious harm.² Pharmacology and pharmacogenetics investigate how these drugs interact with each other in the body to help healthcare providers choose the right medication and the right dosage for patients.³ For more information on medication use and seniors, visit the NIH National Institute on Aging's Senior Health page on medication safety.

Pregnant Women

According to the CDC, one-half of pregnant women take up to four medications daily.⁴ Many medications may be given to pregnant women to manage their health conditions or to help the fetus develop. However, very few medications and supplements have been tested on pregnant women to determine the effectiveness and safety of these agents. A lack of testing can be harmful, however, as certain medications, for example, medications to treat acne⁵ and some dietary and herbal supplements⁶ can cause preterm labor or severe problems in fetal development or long-term development of the infant.

Infants and Children

According to the U.S. Food and Drug Administration (FDA), most drugs prescribed for children have not been tested on that age group. Until the early 2000s, only about 20% of drugs approved by the FDA were labeled for use in children.⁷ Healthcare providers often had to prescribe medication for children without the benefit of research and government regulations to back up their dosages and prescriptions. Because of this, children were often given a smaller dose of a medication for adults. Since 2002, as a result of the Best Pharmaceuticals for Children Act, the NICHD has been identifying drugs and supporting studies that contribute to pediatric labeling and improved medication safety and effectiveness in children.

For more information on the new labeling for children's medications visit the FDA's website for parents.

Certain Races and Ethnicities

Particular drugs can have different effects in different groups of people. It is important that healthcare providers consider their patients’ racial and ethnic backgrounds when prescribing drugs. Here are a few examples of different effects of drugs based on race/ethnicity:

• A cholesterol-lowering drug called rosuvastatin (Crestor^®) has much more powerful effects in Asians than in other groups. One-half the standard dose seems to effectively lower cholesterol levels in Asians, and full doses can increase their risk of heart damage.⁸
• Whites are more likely than Asians to have abnormally low levels of an enzyme called cytochrome p450 2D6, which is important for metabolizing different drugs. Having low levels of the enzyme can put people at risk for accidental overdoses of medications.⁹
• African Americans tend to respond poorly to several classes of blood pressure medicines, including beta-blockers, ACE inhibitors, and angiotensin II agonists.⁹

Research to Improve Drug Safety Testing

Research is also under way to find better and faster ways to test drugs for safety and effectiveness. For example, NIH scientists are working with researchers in the Department of Defense and the FDA to develop “tissue chips,” miniature systems made with living human cells and tissues. In the future, the tissue chips might provide a way to reduce animal testing, make sure that the results of drug tests reflect the drugs’ actions in human beings, and get new drugs approved more quickly.

Participating in Drug Safety Testing

By taking part in a clinical trial, you might be able to assist with learning more about a new drug and whether it is better than those that already exist.
A clinical trial is a biomedical or behavioral research study of human subjects that is designed to answer specific questions about biomedical or behavioral interventions (such as drugs; treatments; devices; or new ways of using known drugs, treatments, or devices). Learn more about clinical trials, including definitions of clinical trials, outcomes of clinical trials, and how to get more information.

Each clinical study has its own criteria for who can participate. These are called eligibility criteria or inclusion criteria. These might be based on age, sex, health status or type of disease, medical history, and other factors. Some studies are open only to participants with certain health conditions, and others recruit healthy volunteers.¹⁰ Doctors and other healthcare providers run the clinical trials according to strict rules set by the FDA and other organizations to make sure that the trials are done safely and ethically.¹⁰

You can find out about clinical trials that you might be eligible for by speaking with your healthcare provider or by checking online at https://www.clinicaltrials.gov/.

The U.S. Food and Drug Administration (FDA) is the federal agency responsible for labeling medications and supplements. However, the approval process is different for prescription and for over-the-counter medications.

Prescription Drugs

The FDA must regulate and approve new prescription drugs before they can be sold to the public. In 2011, the last year for which information is available, the FDA approved 35 new drugs for use by the general public.¹ Although this number may seem small, the approval process for drugs is extensive.

The manufacturer or sponsor follows a series of important steps, through animal studies and clinical trials in humans, to ensure that the medication is safe, does what it claims to do, and will provide a health benefit. Testing is performed first in laboratories and on animals to determine that the drug is safe and try to understand how the drug might work in humans.

"Clinical trial" is the scientific term for a test or study of a drug or medical device in people. These tests are done to see if the product is safe and effective for people to use.

Sometimes, multiple trials are completed to measure the effectiveness of a particular medication. Participants in the studies are often followed over a period of time. For comparison purposes, some are given a placebo, an inactive or "dummy" medication, while others are given the actual drug. The NICHD and other institutes of the NIH help conduct and support the research but are not involved in the approval or labeling process.

The clinical trial phase can take years to complete. However, once research has shown that the drug is safe and useful, the FDA typically reviews and either approves or denies an application for a new drug within 6 months.

View a PDF of the FDA drug approval process. (PDF 2.79 MB)

Over-the-Counter Drugs, Dietary and Herbal Supplements

Over-the-counter drugs and dietary and herbal supplements are not formally approved through the FDA. The active ingredients and labeling of medications and supplements in certain classes (like antacids, for example) are reviewed by the FDA to ensure that acceptable ingredients are used and that they are safe. Drug companies must conform to the requirements in the medication or supplement class, but they do not need formal FDA approval to make and sell over-the-counter medications and supplements.

The label will indicate whether a drug or supplement has been FDA approved. Talk to your healthcare provider about any medications you are currently taking or are considering taking to ensure that they are safe.

Generic Drugs

A generic drug is a medicine that is contains the same active pharmaceutical ingredient as a name-brand drug but is not sold under a brand name. FDA-approved generic drugs meet the same strict standards for safety, efficacy, and quality as name-brand drugs.²

Consumers usually can buy generic drugs at a much lower price than brand-name drugs. Generic versions are not available for every medicine, and in some cases may not be able to be substituted for a brand name product.

When a pharmaceutical company develops a new drug, it is protected under a patent, usually for 20 years. During this time, no other company is allowed to make or sell it. Once the patent expires, that company or another company can make and test another version of the drug. After testing and FDA approval, the company can sell the drug as a generic.³

Consumers can learn whether a generic drug is FDA-approved by using the drug approval references on the FDA website.