Key Concepts
Vocabulary: medicines, drugs, vaccine side effects, additive interaction, synergistic effect, antagonistic, interaction
The Role of Medicines
Types of Medicines
Main Idea: Medicines are classified based on how they work in your body.
People use medicines to help restore their health when they are ill. Medicines are drugs that are used to treat or prevent diseases or other conditions. Drugs are substances other than food that change the structure or function of the body or mind. All medicines are drugs, but not all drugs are medicines. Drugs are effective in treating illness when taken as directed by a physician or according to the label instructions. Medicines that treat or prevent illness can be classified into four broad categories:
Medicines that help prevent disease
Medicines that fight pathogens
Medicines that relieve pain and other symptoms
Medicines that manage chronic conditions, help maintain or restore health, and regulate body’s systems
Preventing Disease
Today, we have medicines that prevent disease. About 95 percent of children receive vaccines, a preparation that prevents a person from contracting a specific disease.
Vaccines Vaccines contain weakened or dead pathogens that cause the disease. When injected into your body, the vaccine produces antibodies that fight those pathogens. Your body also produces memory cells that recall how to make these antibodies. This provides you with long lasting protection against these specific pathogens.
The protection from some vaccines, however, fades over time. The vaccines for tetanus must be given periodically. For other vaccines, like those that prevent the flu, a new vaccine is required every year.
Antitoxins
Antitoxins, like vaccines, prevent disease. They can also help neutralize the effects of toxins. Antitoxins fight the bacteria that produce substances toxic to the body. Antitoxins are usually produced by injecting animals with safe amounts of a specific toxin. This stimulates the animal’s immune system to produce antibodies. These antibodies are then used to make an antitoxin.
Fighting Pathogens
Medicines can also help your body fight the pathogens that cause illness.
Antibiotics
Antibiotics are a class of drug that destroy disease causing microorganisms, called bacteria. Antibiotics such as penicillin work either by killing harmful bacteria in the body or by preventing bacteria from reproducing.
When antibiotics were first introduced, they were considered a miracle drug because they saved so many lives. Some antibiotics, however, can cause nausea or stomach pain. Allergies are another side effect of antibiotic use. Tell your doctor if you experience any negative side effects of an antibiotic, or if you know you are allergic to an antibiotic. Antibiotics also lose their effectiveness. The bacteria that antibiotics kill have adapted to the drug over time.
Bacteria can develop a resistance in two ways: when antibiotics are overused, and when the patient does not finish taking the full prescription. If you do not finish taking all of a prescription, you may not kill all of the bacteria. The remaining bacteria may develop a resistance, or immunity, to treatment.
Antivirals and Antifungals
Antibiotics are effective only against bacteria. They do not cure illnesses caused by viruses. Antiviral drugs are available to treat some viral illnesses, such as the flu. These medicines suppress the virus, but do not kill it. A person who takes antiviral medication for cold sores or fever blisters, which are caused by viruses, will still have the virus in his or her body. As a result, the person often has symptom-free periods followed by flare ups when symptoms reappear. Like bacteria, viruses can develop a resistance to medications. Fungi are another type of pathogen that can infect the body. Antifungals can suppress or kill fungus cells, such as athlete’s foot and ringworm.
Relieving Pain
The most commonly used medicines are analgesics, or pain relievers. Analgesics range from relatively mild medicines, such as aspirin, to strong narcotics, such as opium based morphine and codeine. Aspirin is used to relieve pain and reduce fever. Other analgesics fight inflammation, or redness, swelling, and pain.
Even though aspirin is a widely used drug, it can cause stomach upset, dizziness, and ringing in the ears. Children who take aspirin when they have a fever are at risk of developing Reye’s syndrome, a potentially life threatening illness of the brain and liver. For that reason, aspirin should not be given to anyone under the age of 20 unless directed by a health care professional. Some people who are sensitive to aspirin take acetaminophen or ibuprofen. Acetaminophen is the recommended analgesic for children.
Pain Reliever Dependence
Certain types of medicines that relieve pain can be addictive. These medicines, usually called narcotics, require a doctor’s prescription. Patients who use these drugs can become physically or psychologically dependent on them.
Managing Chronic Conditions
Some medicines are used to treat chronic conditions. These medicines maintain or Store health, and offer people with chronic diseases a higher level of wellness.
Allergy Medicines
Antihistamines reduce allergy symptoms such as sneezing, itchy or watery eyes, and a runny nose. They block the chemicals released by the immune system that cause an allergic response. For people with allergies such as those to peanuts or bee stings, severe symptoms can appear suddenly. An allergic reaction can lead to death. Individuals who know they are allergic to substances that cause severe reactions can ask a doctor to prescribe a single dose shot of epinephrine. The medication is designed to slow down or stop an allergic reaction. The patient is taught to self administer a shot with a single-dose injector.
Body Regulating Medicines
Some medicines regulate body chemistry. Insulin, used by people with diabetes, regulates the amount of sugar in their blood. Asthma sufferers may take medicines every day to control symptoms and prevent attacks. They may also use inhalers during an asthma attack. Cardiovascular medicines are taken to regulate blood pressure, normalize irregular heartbeats, or regulate other functions of the cardiovascular system.
Antidepressant and Antipsychotic Medicines
Medications can also help people suffering from mental illnesses. These medicines can help regulate brain chemistry, or stabilize moods. For example, mood stabilizers are often used in the treatment of mood disorders, depression, and schizophrenia. Proper medication can help people with these diseases live healthy lives. As with other prescribed medications, it is important to talk to your doctor before you stop taking the medication, even if you feel better.
Cancer Treatment Medicines
Some cancers can be treated and even cured. Some medicines can be used to treat cancer. These medicines can reduce rapid cell growth and help stop the spread of cancer cells. One drug, chemotherapy, uses chemicals to kill fast growing cancer cells. Immunotherapy, or biological therapy, uses the body’s immune system to fight the cancer cells. Because these medications can also destroy healthy cells, serious side effects may occur as part of the treatment. Other medications can help treat the side effects.
Taking Medications
Main Idea: Medicines enter the body in a variety of ways.
Medicines can be delivered to the body in many ways. Factors that determine how a medicine is taken include what the medicine is used for, and how it will most quickly and effectively help a person.
Oral medicines are taken by mouth in the form of tablets, capsules, or liquids. These medicines pass from the digestive system into the bloodstream.
Topical medicines are applied to the skin. Transdermal skin patches also deliver a medicine through the skin.
However you take a medicine, it is always important to follow the directions on the medicine label.
Reactions to Medications
Main Idea: The effect of medicine depends on many factors.
Medicines can have a variety of effects. They can cause side effects, reactions to medicine other than the one intended. Some side effects may be mild, such as drowsiness, but others may be more severe, and can even cause death.
Medicine Interactions
When two or more medicines are taken together, or when a medication is taken with certain foods, the combination may have a different effect than when the medicine is taken alone. Types of medicine interactions include the following:
Additive interaction occurs when medicines work together in a positive way. For example, an anti-inflammatory and a muscle relaxant may be prescribed to treat joint pain.
Synergistic effect-the interaction of two or more medicines that results in a greater effect than when each medicine is taken alone-occurs when one medicine increases the strength of another.
Tolerance and Withdrawal
When a person takes a medication for a long period of time, the body can become used to the medication. Problems that may occur include:
Tolerance is a condition in which the body becomes used to the effect of a medicine. The body requires increasingly larger doses to produce the same effect. Sometimes a person will experience “reverse tolerance.” In this condition, the body requires less medicine.
Withdrawal occurs when a person stops using a medicine on which he or she has become physiologically dependent. Symptoms of withdrawal can include nervousness, insomnia, severe headaches, vomiting, chills, and cramps which gradually ease in time. Talk to your health care provider if you experience withdrawal.
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