Kaylan Whitaker Principles of Pharmacology

Outline
Chapter 30

04/18/25

 Pharmacology in a dental setting

 Pharmacology is the science or branch of medicine that includes
the research, development, and manufacture of drugs. A drug is
a substance taken for the prevention, diagnosis, and treatment
of a disease. All drugs must be recognized and defined by the
U.S. Food, Drug, and Cosmetic Act before they can be marketed
for public use in the United States.

 Drugs are derived from many sources. Organic drugs are derived
from living organisms such as plants or animals, and inorganic
drugs are synthesized in the laboratory or extracted from
inorganic compounds. Most drugs today are derived from a
chemical synthesis, which means one or more compounds are
created in the lab into a synthetic drug. This makes them purer in
form than those derived from an originally natural source that
may be contaminated or polluted. The manufacturing of drugs
takes place in a pharmaceutical laboratory.

o Overview of drugs
 A drug is identified by three names:
 • Chemical name is the atomic or molecular structure of the
drug. N-(4-hydroxyphenyl) acetamide is the chemical formula for
acetaminophen.
 • Generic name is the shorthand version of the drug’s chemical
name, structure, or formula, which may be used by any
company; acetaminophen is an example of a generic name.
 • Brand name, or trade name, is controlled by a pharmaceutical
company as a registered trademark; for example, Tylenol is the
brand name for acetaminophen.

o Classification of drugs
  The drugs that are prescribed to treat infections or chronic
conditions are non-controlled. These substances are not subject
to the same limitations as controlled substances. Examples of
the type of non-controlled drugs include the following:

• The drugs that are prescribed to treat infections or chronic

conditions are non-controlled. These substances are not
subject to the same limitations as controlled substances.
Examples of the type of non-controlled drugs include the
following:
• • Antibiotics
• • Insulin
• • Blood pressure medications
• • Cholesterol medications
• • Asthma inhalers

 Controlled Drugs

The drugs and drug products covered under the Federal Comprehensive Drug
Abuse Prevention and Control Act are divided into five classifications of
drugs, with an addition of a sixth classification in some states. The drugs
included in this Act, also referred to as schedule drugs, are classified based
on their potential for abuse, their medical usefulness, and the extent to
which they may lead to physical and psychological dependence or addiction.

Each classification of the control act has specific requirements for ordering,
storing, prescribing, dispensing, and destroying the scheduled drugs within
its definition. Some individual states will have their own controlled
substances acts, which are patterned after the federal law. Some state laws
may be more restrictive, but no state law is less restrictive than the federal
law. The dentist must comply with the provisions of the federal law and those
of the state, province, or territory in which he or she practices (always
following the most restrictive guidelines when the laws differ). Under these
laws, any professional who is authorized to prescribe medications is issued a
federal Drug Enforcement Agency (DEA) identification number, which is
printed on the dentist’s prescription pad.

 Schedule I drugs
Schedule I drugs have no currently accepted medical use in
treatment in the United States and have a high potential for
abuse. Normally, Schedule I drugs cannot be prescribed.
Examples of substances listed in Schedule I include the
following:

• Heroin (diacetylmorphine)

• LSD (lysergic acid diethylamide)

• Marijuana (cannabis, Tetrahydrocannabinol (THC) (see Schedule VI)

• Mescaline (peyote)

• Methylenedioxy-methamphetamine (MDMA) (Ecstasy)

• Methaqualone (Quaalude)

 Scheduled II drugs
Schedule II drugs have limited medical use, high potential for
abuse, and a high risk for physical or psychological
dependence. Prescriptions for these drugs are given only in
writing and cannot be renewed. Examples of Schedule II
narcotics include the following:
• Vicodin
• Cocaine
• Methamphetamine (Meth)
• Methadone (Dolophine)
• Hydromorphone (Dilaudid)
• Meperidine (Demerol)
• OxyContin (Percocet)
• Fentanyl
• Adderall
• Ritalin
  Scheduled III drugs
Schedule III drugs

Schedule III drugs have less abuse potential than the drugs in Schedules I
and II and have accepted medical usefulness. Prescriptions for Schedule III
drugs may be renewed. Examples of Schedule III narcotic drugs typically are
a combination of drugs. Examples of Schedule III non-narcotics include the
following:

• Tylenol with codeine

• Buprenorphine (Suboxone)

• Codeine and hydrocodone with aspirin or Tylenol

• Anabolic steroids such as depo-testosterone

 Schedule IV drugs
Schedule IV drugs

Schedule IV drugs have low abuse potential and have accepted

medical usefulness. Prescriptions for Schedule IV drugs may be
renewed. A patient may have up to five refills of these drugs in 6
months before requiring the patient to be seen by the physician
for renewal. Examples of Schedule IV substances include the
following:

• Alprazolam (Xanax)

• Clonazepam (Klonopin)

• Clorazepate (Tranxene)

• Diazepam (Valium)

• Lorazepam (Ativan)

• Zolpidem (Ambien)

• Ultram (Tramadol)
  Schedule V drugs
Schedule V drugs have the lowest abuse potential and have
accepted medical usefulness. Some states do require that these
drugs be dispensed only by prescription. Under federal law,
however, they are available only under controlled circumstances.
Because of the misuse and illicit distribution of sinus and cold
medicines, many states have passed a law requiring a
prescription or requiring customers to show a photo ID and sign a
logbook before pharmacies will dispense any cold remedy
containing pseudoephedrine. Examples of Schedule V substances
include the following:

• Cough medicines with less than 200 mg of codeine

• Pseudoephedrine (decongestant)

 Prescription terminology
Prescriptions can be handwritten, called into the pharmacy, or submitted
electronically. E-prescriptions are becoming the preferred option, where the
provider sends the electronic prescription straight to the patient’s pharmacy,
through a secure transmit using a special software program.

 Individuals regulate the format and information

to be included on a prescription. State laws
For a prescription to be valid, the following information must
contain:

• Superscription: Includes the patient’s name, address, weight, and age

• Rx: Symbol from the Latin word recipe (meaning “take”)

• Inscription: Main body of the prescription—includes the drug’s name, form,

dose, and number of tablets to dispense

• Subscription: Directions to the pharmacist for information to be included on

the label, such as “dispense 50 tablets”.

• Signature: Instructions for the patient on how to take medicine, when to

take it, and how much to take

• Dentist’s signature
• Dentist’s DEA number

 Prescriptions
A prescription is a scripted instruction provided by a physician or dentist for
the pharmacist to prepare and administer medicine. The physician/dentist
who is authorized to prescribe medication is issued a DEA identification
number and can write a prescription. Under no circumstances can any
member of the dental team prescribe medications. The dental assistant may
dispense medicine in a clinical or emergency situation according to explicit
instructions and under direct supervision of the dentist.

The abuse of prescription drugs is a serious social and health problem. As a

healthcare professional, everyone in the dental setting has a legal and
ethical responsibility to protect the practice from becoming a target for drug
diversion.

 Prescription safeguards

Specific steps to follow include:

• Keep prescription pads under lock.

• Write a prescription so that it cannot be altered (instead of writing 12, write

“twelve” so that a 0 cannot be added to the number).

• Keep a duplicate of all prescriptions in the patient chart (paper and

electronically).

• Dentist should not pre-sign prescriptions.

• Date all prescriptions the day they are issued.

 Issuing prescriptions
The following guidelines apply to the dental setting regarding interaction
with a pharmacy:

• Pharmacies can only dispense Schedule III, IV, and V controlled substances
with a written, oral, or electronic prescription.

• Prescribing drugs for uses outside the scope of a dental procedure and for
family members is not permitted.
• It is recommended that the dentist communicate verbal prescriptions to
the pharmacy or assign one staff person to communicate the prescription
information. Remember the pharmacist is responsible for confirming the
authenticity.

• If a drug, such as a fluoride, chlorhexidine mouth rinse, or antibiotic is

dispensed in the dental office, make sure the container is labeled
appropriately in accordance with the law.

Issuing prescriptions

The following guidelines apply to the dental setting regarding interaction

with a pharmacy:

• Pharmacies can only dispense Schedule III, IV, and V controlled substances
with a written, oral, or electronic prescription.

• Prescribing drugs for uses outside the scope of a dental procedure and for
family members is not permitted.

Every OTC or prescription filled by a pharmacist includes an insert, or

information sheet, that describes the drug. Specific information commonly
listed includes the following:

 Package inserts
• How the drug will affect the body (e.g., relieve itchy, scratchy throat and
eyes)

• For what condition the drug is being prescribed (e.g., allergies)

• Any adverse effects (e.g., drowsiness)

• Any adverse or long-term effects (e.g., possible liver damage)

• Special precautions to follow when taking the drug (e.g., do not drink
alcohol)

• Contraindications to taking the drug (e.g., if taking blood pressure

medication, consult a physician)

• Dosage and route for the drug (e.g., take one tablet each day, orally)

 Administration of medications
Drugs are manufactured in different forms, which include pills, capsules,
liquids, drops, ointments, sprays, gas lotions, and implants. The method by
which a drug is administered determines how quickly or how slowly the drug
will take effect. If a drug is applied directly to the site of use, it is considered
a local-action drug or simply a local drug. This type of drug affects only the
specific area of the body to which it is applied. An example in the dental
office would be a topical anesthetic ointment applied directly where the
injection is to take place. If a drug is taken internally, it is considered a
systemic-action drug or simply a systemic drug. A systemic drug can affect
the whole body through the circulatory system. An example is an antibiotic,
which will eliminate an infection throughout the body when taken for a
specified period.

 Stages of drug action in the body

When a drug enters the body, it undergoes four stages:

1. Absorption: The drug is absorbed from the site of entry. (Sites of entry are
described in Table 30.1.) The speed of absorption varies depending on the
way a drug is administered. The slowest route of absorption is by mouth
(orally).

2. Distribution: Once a drug has entered the bloodstream, its chemical

compound attaches to proteins within the blood. It is then circulated
throughout the body to be released and take effect where it is meant to act.

3. Metabolism: Once the chemical compound is released, the drug becomes

metabolized and is then excreted through the liver or kidneys.

4. Excretion: The drug leaves the body through the kidneys, liver, saliva,
breast milk, and sweat.

 Drugs commonly prescribed in dentistry

Analgesics

Analgesic medications are prescribed for the relief of acute pain,

postoperative pain, and/or chronic pain. This type of drug lessens the
sensory function of the brain by blocking pain receptors. Analgesic
medications belong to two major categories: nonopioid and opioid.

The nonopioid group of analgesics includes nonsteroidal anti-inflammatory

drugs such as acetaminophen (Tylenol), ibuprofen (Advil, Motrin), and aspirin.
This group is indicated for mild to moderate pain, which can include pain of
dental origin, or for postoperative dental pain. It also may be prescribed for
chronic oral-facial pain caused by an inflamed temporomandibular joint
(TMJ). These drugs decrease the prostaglandin concentration, which raises
the level of a person’s pain threshold.
Opioid analgesics are prescribed for moderate to moderately severe pain.
The most common type of drug prescribed is codeine. This type of drug is
always prescribed as a combination preparation, meaning that codeine
would be given in combination with aspirin, acetaminophen, or ibuprofen. It
would be common for a dentist or surgeon to prescribe this after endodontic,
periodontal, or surgical procedures.

 Antibiotics
An antibiotic can be classified as bactericidal or bacteriostatic. Bactericidal
antibiotics such as penicillin directly kill an infecting organism; bacteriostatic
antibiotics such as tetracycline and erythromycin inhibit the production of
bacteria by interfering with their metabolic process, and the bacteria are
then eliminated by the person’s immune defense system. In most cases with
antibiotics, the dentist will select an antibiotic that best combats a particular
type of bacteria. For example, if the patient were diagnosed with an
abscessed tooth, four to six different types of bacteria could be involved. An
antibiotic would be selected to combat the type of bacteria.

 Dental antibiotics come in a variety of forms, including

tablets, gels, threadlike fibers, microspheres (tiny round
particles), and mouth rinses.
 More than 100 different types of antibiotics are available; the
following listed antibiotics are the most common types found
in the dental setting:

• Penicillin is one of the most important antibiotics. It is derived from several

penicillium molds commonly found on bread and fruits. It is one of the most
effective and one of the least toxic of the antimicrobial agents used in
dentistry. Amoxicillin (Amoxil) and ampicillin are examples.

• Cephalosporins consist of a group of antibiotics that are structurally and

pharmacologically related to penicillin. Because cephalosporins are
structurally like penicillin, some patients who are allergic to penicillin may be
allergic to a cephalosporin drug. An example is a cephalosporin such as
cephalexin (Keflex).

• Erythromycin is one of the drugs of choice when penicillin is

contraindicated. Many patients cannot tolerate nausea and stomach upset
commonly associated with erythromycin, so the dentist may have to
prescribe an alternative drug. Examples include macrolides such as
erythromycin (E-Mycin), clarithromycin (Biaxin), and azithromycin
(Zithromax).

• Chlorhexidine is an antibiotic that is used to control plaque and gingivitis in

the mouth or in periodontal pockets. This medication is available as a mouth
rinse and as a gelatin-filled chip that is placed in the deep gum pockets next
to the teeth after root planning.

• Tetracyclines such as demeclocycline, doxycycline, minocycline,

oxytetracycline, and tetracycline can be used in combination with surgery
and other therapies or may be given alone to reduce or temporarily eliminate
the bacteria associated with periodontal disease, to suppress the destruction
of the tooth’s attachment to the bone, or to reduce the pain and irritation of
canker sores.

 Antibiotic prophylaxis
Antibiotic prophylaxis (AP) is prescribing an antibiotic to a patient to prevent
bacterial colonization while undergoing dental treatment. For many years,
patients with certain medical conditions (specifically, cardiac conditions and
prosthetic joint implants) were prescribed an antibiotic to be taken prior to
dental treatment.

Through the guidance of the American Heart Association (AHA) and the
American Academy of Orthopedic Surgeons (AAOS), the American Dental
Association (ADA) continuously updates its recommendations for the use of
antibiotic prophylaxis for dental procedures. In 2021, the ADA approved the
decision to decrease the use of prophylactic antibiotics for people at risk for
developing endocarditis, patients with prosthetic joint implants, and the use
for dental pain and swelling.

 Indications for antimicrobial prophylaxis should be reserved for

patients who are at the greatest risk of post-treatment bacterial related
complications for infective endocarditis, which includes:

• Prosthetic cardiac valves/material

• Congenital heart disease (CHD)

• Previous, relapse, or recurrent infective endocarditis

• Cardiac transplant recipients who develop cardiac valvopathy

 Antifungal agents
As with antibiotics, certain types of antifungal drugs are better at fighting
certain types of fungi. Fungal infections occur less frequently than bacterial
infections, but they can be diagnosed in patients who are
immunocompromised, those who have a poorly fitting prosthesis, patients
with xerostomia, and those who are taking antibiotics. One of the most
prescribed drugs are nystatin (Mycostatin, Nilsat, Nystex).

 Antiviral agents
Viral infections such as hepatitis, hand-foot-and-mouth disease, primary
herpes simplex, recurrent herpes, herpes zoster, and human
immunodeficiency virus (HIV) can all affect the oral cavity. With most viral
infections, some types of lesion commonly appears in the mouth. Antiviral
agents are prescribed in capsule, tablet, liquid, and ointment forms. The
most common antiviral agent is acyclovir (Zovirax).

 Antianxiety agents
Antianxiety drugs have become a large part of “pain-free dentistry.” Patients
who hesitated to go to the dentist because of their fear of pain can now
receive antianxiety medications or sedation dentistry to help manage their
discomfort and anxiety during dental appointments.

 Opioid addiction

Every day, more than 100 people die in the United States from overdosing on
opioids. Opioids are a class of drugs that include the illegal drugs heroin,
fentanyl, and pain relievers available legally by prescription, such as
oxycodone (OxyContin), a combination of acetaminophen and hydrocodone
(Vicodin), codeine, morphine, and many others. Of the deaths involved, 40%
are from taking a prescription pain reliever. It is a serious national crisis that
affects public health with devastating consequences.

The ADA is helping to combat the opioid crisis by informing dentists how
these drugs can be potentially harmful, asking dentists to reflect on how
dental pain is managed, and asking dentists to take steps to keep opioids
from affecting patients by using non-narcotic pain relievers in treatment.

There is an addiction crisis in the United States right now, with many
communities’ advocacy and prevention resources trying to alleviate this
epidemic. Following is a statement by the ADA president on how dental pain
should be managed by the dental profession:

• Consider using non-narcotic pain relievers as the first line of treatment. The
data on opioids find they are not as effective as other treatments and are
associated with more adverse events.

• When an opioid pain reliever is indicated, there are legal limits on the
number of refills and the number dispensed that a prescription may have.

• Counsel patients about the benefits and drawbacks of using opioid

analgesics, especially how these drugs can be addictive. Instruct patients on
how to safely secure, monitor, and dispose of them at home.

• Learn to recognize when a patient might have a substance use disorder or

be prone to addiction. Know how to briefly counsel these patients and refer
them for appropriate treatment.

 Drug complications
An allergic reaction will occur if a drug triggers the immune response.
Repeated exposure to the same drug can produce this type of allergic
response. Reactions can range from a common rash to life-threatening
anaphylactic shock. The most common cause of drug-induced anaphylaxis is
penicillin.

Drug toxicity refers to toxin-induced cell damage and cell death. During the
breakdown of a drug, biochemical damage may take place and harm the cell.
This, in turn, may cause death or mutation of the cell.

Drug interaction takes place when multiple drugs are introduced to the body
system. The severity of this interaction can range from minor incidents to
life-threatening conditions. These types of reactions can be easily prevented
by a dentist who is knowledgeable of proper drug relationships and aware of
all drugs a patient is taking.

Drug tolerance is the loss of a drug’s effectiveness that occurs when a

patient has taken the drug over time and no longer receives the drug’s
beneficial effects. When this occurs, the physician or dentist may need to
increase the dosage or prescribe a different drug.

Drug addiction is a physical dependence on a drug. If the person stops taking

the drug, the body undergoes a withdrawal illness and displays physical
symptoms associated with stopping the use of the drug.