Introduction to Pharmacology

Dental Hygiene and Pharmacology 

There are numerous reasons for dental hygienists to study Pharmacology. This is a process that needs to be continued throughout a professional's lifetime. New drugs are being introduced on a regular basis as well as the use of alternative therapies which can impact day to day life.

Prior to providing any care, a dental professional should review the medical history at the beginning of each appointment. One cannot assume that everything is the same even if only a few days have passed since the last appointment. Individuals may have visited their physician in the interim and drug therapies may have changed. They may have chosen to self medicate or even forgotten to take their medications.

In any case, the dental hygienist needs to be aware of the drugs that the patients are taking in order to prepare for possible medical emergencies, identify oral conditions that may be present as a result of the drugs which may be associated with antibiotics or a number of different drugs, determining the appropriate home care procedures as would be the case with a patient taking drugs that may cause xerostomia and even to plan the best time for appointments, such as would be the case with someone with insulin dependant diabetes.

Being knowledgeable about pharmacology permits the dental hygienist to intelligently discuss the drugs and associated effects with patients and other health care professionals. In the case where a particular medication is causing a condition such as hyperplasia, the dental hygienist needs to first recognize that the condition might be a result of the drug and then educate the patient about the contributing factors that may be exacerbating the undesirable effects of the drug. Also, the dental hygienist might be able to identify that another drug that does not cause the same negative effects which could be substituted. In this situation, it might be helpful to speak with the prescribing health care professional to investigate the possibility of changing the drug regimen.

Lastly, while providing oral health care, the dental hygienist may administer drugs that can either impact the efficacy of another drug or may be contraindicated by another drug or condition, or cause a medical emergency.

As you can see, it is important to be knowledgeable about the drugs as well as the condition for which the drug is being administered.

Types of Drug Names

Knowing the drug classification can provide the health care professional with a great deal of initial information. However, there may be many different drugs with many different names within a class. There may be a chemical name, generic name (non-proprietary) or a trade or brand name (proprietary). The FDA web site has volumes of information relating to pharmacology and is a very valuable resource. The particular address below takes you to the home page for the Orange Book. One of the features of the Orange Book is that you can search for different names for the same drug. Identify 3 trade or brand names for:

1. acetaminophen
2. ibuprofen
3. lidocaine
4. mepivicaine

By visiting the the http://www.fda.gov/cder/ob/default.htm

In Chapter 1 of your text book, you read about the role of the FDA in drug approval. Explore the FDA's web site, www.fda.gov and discuss your thoughts about the value of the web site in the Discussion Board on Blackboard. Then, read the history on the FDA on the same web site. On the Discussion Board, address the reason(s) for the creation of the FDA an if the reasoning reminds you of any problem(s) existing in society today.

The Law and Pharmacology

There are additional agencies and legislation that contribute to the governance of drugs. They include:

• Harrison Narcotic Act (1914) - Established regulations governing the use of opium, opiates and cocaine. In 1937, marijuana was added
• Food and Drug Administration (FDA) - Is a Department of Health and Human Services which grants approval for drugs sold in the US, determines which drugs are prescriptions or OTC and regulates the labeling and advertising of Rx drugs
• Federal Trade Commission (FTC) -Regulates the trade practices of drug companies and advertising of foods, OTC drugs and cosmetics
• Drug Enforcement Agency (DEA) - Is part of the Department of Justice, Administers the Controlled Substances Act of 1970 and regulates the manufacture, distribution and dispensation of substances that have a potential for abuse such as opioids, stimulants and sedatives
• Omnibus Budget Reconciliation Act of 1990 (OBRA) - Requires that pharmacists must provide patient counseling and prospective drug utilization review for Medicaid patients
• Orphan Drug Program - Is a result of the Orphan Drug Act of 1983 which provides incentives for research for rare diseases which are defined as those disease affecting fewer than 200,000 individuals
• Compassionate Access to Unapproved Drugs - This act provides patients access to experimental drugs prior to completed studies as death would most likely occur before the end of the studies
• Food, Drug and Cosmetic Act of 1938 - Prohibits the commerce of drugs shown not to be effective or safe, prohibits refills unless indicated and requires certain drugs to be sold by prescription only = "Caution:Federal law prohibits dispensing without prescription".

Prescriptions

Which brings us to prescription writing, Every state has their own requirements for prescriptions but most follow a similar format. There are two methods of describing the parts of a prescription. The first is as follows:

• The heading - Name, address and telephone number of prescriber, name, address, age and telephone number of the patient
• Body -Rx, The name of the drug, amount to be dispensed, patient directions
• Closing - Prescribers signature, DEA number, Refill instructions, If generic substitution permitted

The second method is a follows:

• Superscription - Patient's name, address, age and date
• Inscription - Name of the drug and the strength of the drug (i.e., 500 mg tablet)
• Subscription - Direction to the pharmacist (dosage form and amount to be given -› Disp.)
• Transcription - also referred to as the signa, Directions to the patient (Sig.)
• Signature - Signature of the person prescribing the medication

Visit http://www2.kumc.edu/instruction/prescriptStuff/format.htm#components and identify the 3 separate sections of the prescription as described as method 1.

Abbreviations are very common in prescription writing. It is necessary to know the meaning of the abbreviations to avoid possible misuse of the drug. The laws governing the structure of the prescription and the abbreviations are to protect the public. On the website that you just visited, what was the issue that has been included into law in Texas and is being considered in other states?

Review Activities

Here are some activities to test your knowledge. Use these to prepare for the quiz that follows.

FDA Review

Federal Agencies

Prescription Abreviations

Drug Administration

The administration of a drug is also known as the Pharmaceutic Phase. Drugs need to be in a solution for absorption to occur. This phase is applicable to drugs administered as tablets or capsules. After swallowing the drug, it dissolves in body fluids in the gastrointestinal tract. Enteric coated drugs dissolve in the small intestine.

The route of administration effects the onset of the drug effects. Drugs can be administered by the following methods:

Enteral Route

Parenteral Route

Drug Absorption, Distribution and Metabolism

Once the drug is administered, the Phamacokinetic phase or absorption begins. The route of administration, the solubility of the drug and the presence of inflammation influence the rate of absorption. Intravenous administration is the fastest, while oral injection is the slower. Water soluble drugs are absorbed more quickly.

The Phamacokinetic phase continues with the distribution of the drug. For a drug to be therapeutic a sufficient amount of the drug must be available in the system. Too much of the drug may cause a toxic effect, while too little will not do what it is suppose to do.

The next step in the Phamacokinetic phase is metabolism or biotransformation. Metabolism most often occurs in the liver. But may also occur in the kidneys, lungs, plasma and intestinal mucosa.

Lastly, the final phase of the Phamacokinetic process is excretion. Most often excretion occurs my the kidneys in urine. But drugs may also be eliminated through sweat, saliva, bile, breast milk, breathing and feces.

As discussed in the text, there are numerous factors that influence the effects of drugs. An example is an individual with uncontrolled diabetes and periodontal disease. An individual with uncontrolled diabetes is at higher risk for periodontal disease due to the body's decreased ability to effectively respond to inflammation. However, the therapeutic effect of insulin is decreased in the presence of inflammation. As you can imagine, without careful monitoring of the circulating drug, resolution of both diseases may be challenging.

The Phamacokinetic Phase is very clearly illustrated in these animations:

• Absorption
• Distribution
• Binding
• Excretion

The Pharmcodynamic Phase

The Pharmacodynamic Phase is how the drug effects the body. The effects include the primary effect, which is the desired or therapeutic or primary effect and secondary effects, which may be desirable or undesirable. Secondary effects are also known as side effects or adverse effects

Dose-Response Curve

The dose-response curve is is used to determine both the therapeutic dose and the dose that will result in undesirable effects. Below is the dose-response curve for Morphine. The blue curve illustrates the dose which should produce a therapeutic effect. The magenta curve illustrates the dose which may cause respiratory distress. Obviously, this is not desirable! the area between the 2 curves depicts the dose which can produce the primary effect without the negative secondary effect.

Definitions

The potency of a drug is the amount of the drug needed to produce a response. It is expressed as the Median Effective Dose(ED₅₀) or the amount of the drug that produces half of the maximum effect. The smaller amount of the drug needed to produce the response, the more potent.

Efficacy is the maximum intensity of a response the drug can produce. More of the drug will not produce better results but may produce a negative effect. So, in this case, more may not be better!

Concentration is addressed by the Minimum Effective Concentration (MEC) which is the smallest dose that is efficacious. Or, Toxic Concentration which is the amount of the circulating drug that causes toxicity.

The duration of action is how long the dose of the drug will have an effect.

Idiosyncrasy is an unusual or abnormal response to a drug that is thought to occur as a result of a genetic deficiency.

Tolerance is a decreased response to a drug. When tolerance occurs an increased dose of the drug is required to achieve the same effect. This often happens when a drug is taken over a period of time. Tolerance is a sign of dependence.

• Tachyphylaxis is a quick onset of tolerance. This may occur with a local anesthetic agent. If a second of the same injection is given within a short period of time (hours) the second injection would be ineffective if tachyphylaxis is occurring. This type of tolerance is short lived and the injection will be effective at a later date

Drug-Drug Interactions

• Additive drug reaction - the sum of 2 drugs given together = the effect of each drug given alone (1+1=2)
• Synergistic drug reaction - the sum of 2 drugs given together > the effect of each drug given alone (1+ 1 =3)
• Antagonist drug reaction - one drug interferes with the action of the other = decreased effect of one drug (1+1=1)

A division of the FDA monitors adverse reactions to drugs. In some cases the reporting is mandatory and in others it is voluntary. Visit the FDA web site and type in "MedWatch" in the search box. Complete the FDA MedWatch and Patient Safety Tutorial and from the Group Assisment file, students 1-5 (Group 1) discuss the objective, student 6-10 (Group 2) dicuss the second objective, students 11-15 (Group 3) discuss the third objective and students 16-19 (Group 4) discusss the last objective provided at the beginning of the tutorial on the Discussion Board titled "MedWatch".

Review Activities

Here are some activities to test your knowledge. Use these to prepare for the quiz that follows.

Phamacokinetics

Pharmacodynamics

Drug Therapy of Today

The utilization of drugs is experiencing a significant change in the the United States. On the Discussion Board provide your thoughts on how the media and the Internet has changed drug utilization.

Drug Abuse

Drug abuse may be a result of a psychological or physical dependence. A psychological dependence occurs when a person believes that he or she cannot maintain optimal performance without having taken the drug. It can range from a mild desire to a compulsive obsession. Although there is not a physical need for the drug, the feeling of "need" can be more powerful than drugs with a physical dependence. A physical dependence is an altered physiologic state that results from constantly increasing drug doses. A physical dependence is determined by the presence of withdrawal symptoms if the drug is withheld.

Alternative Medicine

Visit the National Center for Complementary and Alternative Medicine, explore the site and report on a section or topic that you found interesting. Or maybe you know someone who is using alternative medicine, explore what is known about that particular therapy and its effectiveness based on scientific literature. Post your thoughts on the Discussion Board.

Lastly, on the Discussion Board debate the value of Brand and generic drugs and if you agree with the drug companies that they need to have the lengthy patents and higher cost to cover the cost of research and development. The odd numbered students will be in favor of Brand drugs and the even numbered students will be in favor of generic drugs. Post your thoughts on the "Wiki entitled Brand vs. Generic"

 Crossword Puzzle

Complete the Crossword Puzzles to review the section.

After completing the first puzzle, a new puzzle will be presented when the activity is reopened.

There are several puzzle, so just keep going until you see the same clues.

In the case where the answer is two words, the space between the two words is omitted in the puzzle, i.e. active transport would be active transport. Have fun!

Congratulations, you have completed the first module!