1. Drugs—biologically active substances that can modify cellular function; used in the prevention, diagnosis, treatment, and cure of disease or in the prevention of pregnancy

2. Nomenclature—each drug has several names

1. Physicians’ Desk Reference (PDR)¹—provides an index of drug manufacturers, brand and generic names of drugs, product categories, drug identification and information guide, and diagnostic information; updated yearly; most commonly used reference in the oral health care environment; inclusion of a drug in this reference is paid for by the manufacturer (seldom-used products not listed); information about the drug is similar to that found in the package insert, but this information is not updated regularly

2. Facts and Comparisons²—drugs organized by pharmacologic classes; complete listing; updated monthly; contains both prescription and over-the-counter (OTC) drugs; prepared by independent editors

3. Applied Pharmacology for the Dental Hygienist;³ Oral Pharmacology for the Dental Hygienist;⁴ Basic Principles of Pharmacology with Dental Hygiene Applications⁵—basic pharmacology textbooks for the dental hygienist; all three focus on dental hygiene considerations and provide the necessary information to avoid adverse reactions and drug interactions

4. Mosby’s Dental Drug Reference⁶—provides comments on a limited number of drugs specifically related to dentistry; includes dental drug interactions, oral side effects, and dental considerations

5. Drug Information Handbook for Dentistry⁷—provides an alphabetical listing of drugs and their effects on dental therapy; sections on managing medically compromised clients and treating specific oral conditions; information on dental office emergencies; comprehensive appendix on dental drug interactions and OTC dental products

6. Drug Information for the Health Care Professional, Volume 1, and Advice for the Patient, Volume 2;⁸ published yearly and updated quarterly by U.S. Pharmacopoeia; includes basic information regarding pharmacology, pharmacokinetics, adverse reactions, drug interactions, doses, and advice to the patient

1. Effective dose (ED) 50—dose that produces 50% of the maximum response, or the dose of a drug that produces a specific response in 50% of the subjects

2. Lethal dose (LD) 50—dose that is lethal to (kills) 50% of the subjects; laboratory animals are used to derive LD

3. Therapeutic index (TI)—LD50 divided by ED50; a measure of the safety of a drug

4. Onset—time required for a drug’s effect to begin; onset is short if the drug is given intravenously, longer if administered orally

5. Duration—length of time a drug’s effect lasts; related to a drug’s half-life

6. Half-life ()—time required for a drug’s serum concentration to decrease by 50%; five half-lives are required for a drug to be eliminated from the body

7. Potency—amount of drug (e.g., in milligrams) needed to produce an effect; the more potent an agent is, the lower is the dose needed to produce an effect (Figure 11-2)

8. Efficacy—the desired effect elicited by a drug, independent of dose (see Figure 11-2)

9. Tolerance—physiological response to the same dose produces less effect, or a higher dose is required to achieve the same effect

10. Therapeutic effect—desired pharmacologic effect

1. Oral (PO)—by mouth; easiest to use; good client acceptance; however, a latency period exists

2. Rectal—administration by suppository or enema; produces either local or systemic effect

3. Parenteral—a route other than an oral route; usually refers to an injection

4. Intravenous (IV)—administration into a vein; shortest onset of action and higher risk of adverse events compared to other routes of administration

5. Intramuscular (IM)—administration into the muscle; sometimes painful

6. Subcutaneous (SC, SQ)—injected beneath the skin (e.g., insulin)

7. Intradermal—injected into the dermis (e.g., skin test for tuberculosis produces a bleb [bump]; progesterone implants are administered intradermally)

8. Intrathecal—administered into the spinal fluid (e.g., to treat meningitis)

9. Intraperitoneal—injected into the peritoneal cavity (abdomen)

10. Oral or nasal—particles, volatile liquids, or gasses that are inhaled (e.g., nitrous oxide–oxygen (N₂OO₂) analgesia; as are some medications used to treat allergies and asthma)

11. Topical—ointments or creams applied to the skin or mucous membranes (e.g., hydrocortisone)

12. Sublingual—a tablet that dissolves or a solution that is sprayed under the tongue (for systemic effect)

1. Capsule—gelatin shell

2. Tablet—compressed or molded dosage form

3. Ointment or cream—semi-solid for topical application

4. Suppository—penile, rectal, or vaginal; systemic or local

5. Solution—single-phase system consisting of more than one constituent

6. Suspension—insoluble particles in liquid (e.g., milk of magnesia)

7. Emulsion—two immiscible (not mixable) liquids (e.g., oil and water)

8. Elixir—sweetened and hydroalcoholic (water and alcohol mixture)

9. Tincture—usually alcoholic

1. Varies depending on the client’s:

2. Pediatric dose

A Side effect on a nontarget organ—effect on an organ other than that intended to be altered (e.g., insomnia resulting from a β₂-agonist or theophylline); dose-related and often predictable

B Toxic reaction—predictable and dose-related effect on a target organ (e.g., insulin can lower blood glucose levels to the point of hypoglycemia)

C Allergic reaction—varies from mild rash to anaphylaxis; involves an antigen–antibody reaction (e.g., rash from penicillin); can include urticaria, soft tissue swelling, and difficulty breathing; not predictable and not dose related

D Idiosyncrasy—abnormal drug response that is genetically related

E Interference with natural defense mechanisms—body is less able to fight infection (e.g., steroids weaken the immune system)

F Teratogenic effect—adverse effect on a fetus (e.g., alcohol intake during pregnancy produces fetal alcohol syndrome)

G Safety—related to the therapeutic index; therapeutic index: LD50/ED50. The measure of a drug’s safety can be determined using this formula; the larger the number of this ratio, the safer is the drug

A Absorption depends on:

B Distribution of the drug (Figure 11-3)⁹

C Metabolism (biotransformation)—takes place mainly in the liver by hepatic microsomal enzymes; metabolites are more polar, less protein bound, and more easily excreted; drugs metabolized by microsomal enzymes can affect their own metabolism or that of other drugs (e.g., either increasing [as with barbiturates] or decreasing [as with cimetidine, erythromycin] the rate of metabolism); biotransformation is a source of drug interactions

D Excretion—usually by way of kidneys (urine); can also occur through feces (enterohepatic circulation), sweat, tears, or lungs (e.g., N₂O is exhaled)

A Agonist—a drug that has an affinity for a receptor site and binds to it, producing an effect (e.g., opioid [narcotic] analgesic agent)

B Antagonist—a drug has an affinity for a receptor site and binds to it but produces no effect; competitively blocks the effect of an agonist (e.g., naloxone, an opioid [narcotic] antagonist blocks the effect of the agonist, an opioid)

1. The SANS is activated by fear (the “fight-or-flight” response)

2. Catecholamine—chemical structure of some adrenergic agents

3. Receptors in the SANS include:

1. The central nervous system (CNS)—stimulation produces increased alertness; may also cause anxiety, anorexia

2. Stimulation of the heart—S+, produces

3. Vascular effects (on the arterial tree) result from

4. Mydriasis (pupil dilation) and reduced intraocular pressure; useful in treating glaucoma

5. Bronchodilation (by action of β₂-agonist); useful in treating clients with asthma

6. Alterations in the blood glucose level; persons with diabetes mellitus must be observed for adverse reactions

7. Production of thick, viscous saliva

1. Tricyclic antidepressants (e.g., amitriptyline [Elavil], imipramine [Tofranil])—interaction increases blood pressure; produces dysrhythmias

2. β-Blockers (e.g., propranolol [Inderal])—produce hypertension and bradycardia (slowed HR)

3. Antidiabetic agents (e.g., insulin, glipizide [Glucotrol], glyburide (DiaBeta)—increase the blood glucose level

4. Monoamine oxidase inhibitors (MAOIs)—no problem with epinephrine; indirect-acting amines (e.g., pseudoephedrine) must be avoided

5. General anesthetics—halogenated hydrocarbons (e.g., halothane [Fluothane]) sensitize the myocardium to catecholamines; epinephrine is a catecholamine; increase the chance of arrhythmia/dysrhythmias

1. Medical purposes—treatment of:

2. Dental purposes

1. Examples

2. Advantages of adrenergic vasoconstriction

3. Disadvantages of adrenergic vasoconstriction

4. Minimize toxicity by:

5. Dental hygiene considerations

1. Prazosin (Minipress)

2. Terazosin (Hytrin)

3. Doxazosin (Cardura)

1. Propranolol (Inderal)

2. Metoprolol (Lopressor)

3. Atenolol (Tenormin)

1. Check the client’s blood pressure and pulse—these medications can increase or decrease the heart rate

2. Raise the dental chair slowly, and allow the client to remain seated for a few minutes to minimize the risk of orthostatic hypotension