Applied Pharmacology for the Dental Hygienist.

Applied Pharmacology for the Dental Hygienist. 1. A drug is defined as a biologically active substance that can modify a. the environment. b. the pH of tissue. c. cellular function. d. immune response. ANS: C A drug can modify cellular function. A general understanding of drug action allows the dental hygienist to make informed decisions regarding possible drug interactions or adverse reactions for the patient. It is a concern that discarded drugs may be affecting the environment, but this is not the definition of a drug. Some drugs may have the capacity to modify body compartment pH; however, this is not the definition for a drug. Some drugs may have the capacity to modify the immune response, but this is not the definition of a drug. DIF: Recall REF: Introduction | p. 11 OBJ: 1 TOP: NBDHE, 6.0. Pharmacology 2. In comparing two drugs, the dose-response curve for the drug that is more efficacious would a. be closer to the y-axis. b. be farther from the y-axis. c. have a greater curve heigN ht. R d. have a higher median effecUtiveSdosNe (ETD50). ANS: C Efficacy is an expression of maximum intensity of effect or response that can be produced by a drug. The other choices refer to indicators of drug potency, not efficacy. The potency of a drug is a function of the amount of drug required to produce an effect. The potency of drug is shown by the location of that drug’s curve along the log-dose axis (x-axis). DIF: Comprehension REF: Characterization of Drug Action (Efficacy) | p. 11 OBJ: 1 TOP: NBDHE, 6.0. Pharmacology 3. Administering a drug of greater potency is better because drugs of greater potency do not require as high a dose. a. Both parts of the statement are true. b. Both parts of the statement are false. c. The first part of the statement is true; the second part is false. d. The first part of the statement is false; the second part is true. ANS: D Applied Pharmacology for the Dental Hygienist 8th Edition Haveles Test Bank The first part of the statement is false, the second part is true. The absolute potency of a drug is immaterial as long as the appropriate dose is administered. If equally efficacious, both drugs will produce the same effect. Both meperidine and morphine, for example, have the ability to treat severe pain, but approximately 100 mg of meperidine would be required to produce the same action as 10 mg of morphine. The dose of meperidine needed to produce pain relief is larger than that for morphine. Less potent drugs require higher doses to produce therapeutic effects whereas more potent drugs can reach toxic levels at lower doses. DIF: Application REF: Characterization of Drug Action (Potency) | p. 11 OBJ: 1 TOP: NBDHE, 6.0. Pharmacology 4. Which of the following statements is true regarding the therapeutic index (TI) of a drug? a. A drug with a large TI is more dangerous than a drug with a small TI. b. The formula for TI is ED50/LD50. c. ED50 is 50% of the effective clinical dose. d. TI is the ratio of the median lethal dose to the median effective dose. ANS: D LD50 is the dose causing death in 50% of test animals and ED50 is the dose required to produce the desired clinical effect in 50% of test animals. The greater the TI, the safer the drug. The formula is TI = LD50/ED50. The ED50 is the dose required to produce the desired clinical effect in 50% of test animals, not 50% of the effective clinical dose. DIF: Comprehension REF: Characterization of Drug Action (Therapeutic Index) | p. 12 OBJ: 1 TOP: NBDHE, 6.0. Pharmacology 5. Which of the following statement is true concerning the mechanism of action of drugs? a. Drugs are capable of imparting a new function to the organism. b. Drugs either produce the same action as an exogenous agent or block the action of an exogenous agent. c. Drugs either produce the same action as an exogenous agent or block the action of an endogenous agent. d. Drugs either produce the same action as an endogenous agent or block the action of an endogenous agent. ANS: D Drugs either produce the same action as an endogenous agent or block the action of an endogenous agent. Drugs do not impart a new function to the organism; they merely either produce the same action as an endogenous agent or block the action of an endogenous agent. DIF: Comprehension REF: Mechanism of Action of Drugs | p. 12 & 13 OBJ: 2 TOP: NBDHE, 6.0. Pharmacology 6. When different drugs compete for the same receptor sites, the drug with the stronger affinity for the receptor will bind to a. more receptors than the drug with the weaker affinity. b. fewer receptors than the drug with the weaker affinity. c. all of the available receptors. d. none of the available receptors. ANS: A Applied Pharmacology for the Dental Hygienist 8th Edition Haveles Test Bank When different drugs compete for the same receptor sites, the drug with the stronger affinity for the receptor will bind to more receptors than the drug with the weaker affinity. More of the drug with weaker affinity will be required to produce a pharmacologic response. Drugs with a stronger affinity for receptor sites are more potent than drugs with weaker affinities for the same site. DIF: Recall REF: Mechanism of Action of Drugs (Receptors) | p. 13 OBJ: 2 TOP: NBDHE, 6.0. Pharmacology 7. When a drug has affinity for a receptor and produces no effect, it is called a(n) a. agonist. b. competitive antagonist. c. competitive agonist. d. physiologic agonist. ANS: B A competitive antagonist has affinity for a receptor, combines with the receptor, competes with the agonist for the receptor, and produces no effect. An agonist has affinity for a receptor, combines with the receptor, and produces an effect. Competitive agonist is nonsensical terminology. A physiologic antagonist has affinity for a site different from that of the agonist in question. DIF: Recall REF: Mechanism of Action of Drugs (Receptors [Agonists and Antagonists]) | p. 13 OBJ: 2 TOP: NBDHE, 6.0. Pharmacology 8. A noncompetitive antagonist a. binds to the same receptor site as the binding site for the agonist. b. causes a shift to the right in the dose-response curve. c. enhances the maximal response of the agonist. d. reduces the maximal response of the agonist. ANS: D A noncompetitive antagonist reduces the maximal response of the agonist. Noncompetitive antagonists bind to a receptor site that is different from the binding site for the agonist. A competitive antagonist will cause a shift to the right in the dose-response curve. DIF: Recall REF: Mechanism of Action of Drugs (Receptors [Agonists and Antagonists]) | p. 13 OBJ: 2 TOP: NBDHE, 6.0. Pharmacology 9. Which of the following is not a subject of pharmacokinetics? a. Physiologic action of drugs b. Metabolism of drugs c. Elimination of drugs d. Absorption of drugs ANS: A The physiologic action of drugs is a subject of pharmacology, not pharmacokinetics. Pharmacokinetics does have to do with the subjects of absorption, distribution, metabolism, and excretion of drugs. Applied Pharmacology for the Dental Hygienist 8th Edition Haveles Test Bank DIF: Comprehension REF: Pharmacokinetics | p. 14 OBJ: 3 TOP: NBDHE, 6.0. Pharmacology 10. Which of the following statements is (are) true concerning passage across body membranes? a. The membrane lipids make the membrane relatively permeable to ions and polar molecules. b. The lipid molecules orient themselves so that they form a fluid bimolecular leaflet structure with the hydrophobic ends of the molecules shielded from the surrounding aqueous environment. c. Membrane carbohydrates make up the structural components of the membrane and help move the molecules across the membrane during the transport process. d. Both A and B are true. e. Both B and C are true. ANS: B The lipid molecules orient themselves so that they form a fluid bimolecular leaflet structure with the hydrophobic ends of the molecules shielded from the surrounding aqueous environment. The hydrophilic ends are in contact with water. The membrane lipids make the membrane relatively impermeable to ions and polar molecules. Membrane proteins make up the structural components of the membrane and help move the molecules across the membrane during the transport process. DIF: Comprehension REF: Pharmacokinetics (Passage Across Body Membranes) | p. 14 OBJ: 3 TOP: NBDHE, 6.0. Pharmacology 11. Which of the following choices is the process by which a substance is transported against a concentration gradient? a. Passive transfer b. Active transport c. Facilitated diffusion d. Filtration ANS: B Active transport is a mechanism for movement of substances, often against a concentration gradient, that uses the energy of the cell to actively pump the substance from one side of a membrane to the other. Passive transfer and filtration entail the passage of substances in a manner proportional to their concentration on each side of the membrane. The substances move without any assistance. Facilitated transport uses a carrier protein but cannot transport substances against a gradient. DIF: Recall REF: Pharmacokinetics (Passage Across Body Membranes [Specialized Transport]) | p. 14 OBJ: 3 TOP: NBDHE, 6.0. Pharmacology 12. Drugs that are weak electrolytes will cross body membranes best when they are (1) nonionized, (2) ionized, (3) polar, (4) nonpolar, (5) lipid soluble, (6) water soluble. a. 1, 3, 5 b. 1, 3, 6 c. 1, 4, 5 d. 1, 4, 6 Applied Pharmacology for the Dental Hygienist 8th Edition Haveles Test Bank e. 2, 4, 5 ANS: C Drugs that are weak electrolytes will cross body membranes best when they are nonionized, nonpolar, and lipid soluble. These drugs dissociate in solution and equilibrate into a nonionized form and an ionized form. The nonionized, or uncharged, portion acts as a nonpolar, lipid-soluble compound that readily crosses body membranes. The ionized portion of drugs that are weak electrolytes will traverse membranes with greater difficulty because they are less lipid soluble. DIF: Comprehension REF: Pharmacokinetics (Passage Across Body Membranes [Effect of Ionization]) | p. 15 OBJ: 3 TOP: NBDHE, 6.0. Pharmacology 13. Increasing the pH of a solution will cause a. a greater percentage of a weak base in the solution to be in the ionized form. b. a greater percentage of a weak acid in the solution to be in the un-ionized form. c. the hydrogen ion concentration to increase. d. a greater percentage of a weak base in the solution to be in the un-ionized form. e. no change in the relative ionization of weak acids or weak bases. ANS: D Weak bases become ionized at low pH and un-ionized at higher pH. If the pH of the site rises, the hydrogen ion concentration will fall. For weak bases, this results in the un-ionized form (B), which can more easily penetrate tissues. Conversely, if the pH of the site falls, the hydrogen ion concentration will rise. This results in an increase in the ionized form (BH+ ), which cannot easily penetrate tissues. DIF: Comprehension REF: Pharmacokinetics (Passage Across Body Membranes [Effect of Ionization]) | p. 15 OBJ: 4 TOP: NBDHE, 6.0. Pharmacology 14. When the acidity of the tissue increases, as in instances of infection, the effect of a local anesthetic decreases; therefore, the local anesthetic is a weak acid. a. Both parts of the statement are true. b. Both parts of the statement are false. c. The first part of the statement is true; the second part is false. d. The first part of the statement is false; the second part is true. ANS: C The first part of the statement is true, the second part is false. Infections lead to an accumulation of acidic waste products, which lowers the pH of the local area. Local anesthetics must penetrate the nerve cell membrane to cause their action. They become more ionized as the pH drops. This property is a characteristic of weak bases, not weak acids. Local anesthetics are weak bases. Weak bases are better absorbed when the pH is greater than the pKa. A weak base is associated and ionized when the pH is less than the pKa.