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Which antibiotic is MOST associated with aplastic anemia as a side effect?
A. Metronidazole
B. Chloramphenicol
C. Bacitracin
D. Clindamycin
E. Sulfamethoxazole
- B. Chloramphenicol (bacteriostatic, considered a prototypical broad-spectrum antibiotic, alongside the tetracyclines)
- Three significant side effects are associated with chloramphenicol.
- 1. One is a dose-dependent pancytopenia (bone marrow inhibition).
- 2. The second is a non-dose-dependent effect on bone marrow, which can be fatal (aplastic anemia).
- 3. The third is "gray baby syndrome," a liver failure in fetuses that may occur when the pregnant mother takes chloramphenicol.
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Which condition requires antibiotic prophylaxis (as per 1997 American Heart Association recommendations)?
A. Cardiac pacemaker
B. Cardiac bypass
C. Prosthetic cardiac valves
D. Functional heart murmur
- C. Prosthetic cardiac valves
- *Most cardiac problems do not require prophylactic antibiotics
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How much amoxicillin should be given to a 30 kg child for subacute bacterial endocarditis prophylaxis?
A. 450 mg
B. 600 mg
C. 750 mg
D. 1,500 mg
E. 2,000 mg
- D. 1,500 mg
- 1. First, the child dose for amoxicillin is based on 50 mg/kg of body weight. Multiplying 30 kg 50 mg/kg gives 1,500 mg.
- 2. Next, you need to know that child dose never exceeds the adult dose (which is 2,000 mg for amoxicillin), so in this case the answer remains 1,500 mg.
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If a drug is highly bound to plasma proteins, it
A. has a large volume of distribution.
B. has a high renal clearance.
C. is a likely candidate for drug
interactions.
D. is most likely carried by
alpha-glycoprotein.
E. is a quaternary ammonium salt.
- C. is a likely candidate for drug interactions.
- Drugs with extensive plasma protein binding usually have low Vd (volume of distribution) values and slow renal elimination because only the free fraction is filtered. Albumin is the major plasma protein to which drugs bind, and the constant positive charge on quaternary amines prevents their binding to plasma proteins. Competition between drugs for plasma protein binding sites can lead to drug interactions.
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Enhancement of the effects of bradykinin is MOST likely to occur with drugs such as
A. clonidine.
B. diazoxide.
C. lisinopril.
D. losartan.
E. propranolol.
- C. lisinopril.
- ACE inhibitors prevent the conversion of angiotensin I to angiotensin II and lower blood pressure by decreasing the formation of aldosterone and vasoconstrictive action of AII at AT-1 receptors. ACE inhibitors also inhibit the metabolism of bradykinin, and this leads to additional hypotensive effects because bradykinin is an endogenous vasodilator.
- -pril are ACE inhibitors
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All of the following statements are true of local
anesthetics EXCEPT one. Which one is the EXCEPTION?
A. They decrease the electrical excitation
threshold
B. They decrease the rate of nerve impulse
C. They reduce the rate of rise of the action potential
D. They slow nerve impulse propagation
E. They inhibit the ionic influx (sodium
ions)
- A. They decrease the electrical excitation threshod
- Local anesthetics prevent generation and conduction of nerve impulses through a number of means: (1) increasing the electrical excitation threshold, (2) decreasing the rate of nerve impulses, (3) inhibiting the ionic fluxes, (4) reducing the rate of rise of the action potential, and (5) slowing nerve impulse propagation. The main effect of the anesthetic is the inactivation of membrane sodium channels.
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Allergic reaction to anesthetic is
A. common and more likely with esters.
B. common and more likely with amides.
C. rare and more likely with esters.
D. rare and more likely with
amidesv
- C. rare and more likely with esters.
- Allergy to anesthetics is rare. Allergy to amide anesthetics is extremely rare, whereas allergy to ester types is slightly more common but still rare. Even when allergy is noted from an injection, the most common cause is reaction to methylparaben, a preservative.
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Which of the following local anesthetics is associated with an allergy to para-amino benzoic acid?
A. Prilocaine
B. Bupivacaine
C. Etidocaine
D. Chloroprocaine
E. Mepivacaine
- D. Chloroprocaine (an ester)
- Patients can be allergic to the "class" of local anesthetics as well as to individual groups of these agents, such as the esters or amides. The esters are derivatives of para-aminobenzoic acid, so a patient who has an allergy to para-aminobenzoic acid should not be administered any ester, such as chloroprocaine, procaine, or tetracaine.
- Bupivacaine (choice B), etidocaine (choice C), mepivacaine (choice E), and prilocaine (choice A) are all amide-based anesthetics and would be appropriate for administration to patients with para-aminobenzoic acid allergy.
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Hydrochlorothiazide is a diuretic used in the treatment of hypertension and has been associated with which of the following?
A. Hypernatremia
B. Hyperkalemia
C. Decreased total cholesterol blood levels
D. Decreased glucose tolerance
E. All of the above
- D. Decreased glucose tolerance
- Hydrochlorothiazide is known to increase fasting blood glucose, especially in diabetic patients; therefore, this medication decreases glucose tolerance. In diabetic patients, it may be necessary to make dosage adjustments of both oral hypoglycemic agents and/or insulin to maintain euglycemia when taken concomitantly with this medication. Hydrochlorothiazide is associated with increased blood levels of uric acid, increased total cholesterol blood levels, hypokalemia, and hyponatremia.
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Which of the following compounds are commonly used during an ocular examination?
A. Contrast agents
B. Topical agents
C. Dyes
D. Mydriatic agents
E. All of the above
There are a number of agents used during the examination of the eye. Commonly used agents include contrast agents,topical anesthetics, dyes, and mydriatic agents. The mydriatic agents are usedare used to dilate the pupil, allowing the clinician to view the back of theeye. Miotic agents would not be used; these agents do the opposite and causethe pupil to constrict, thus making it more difficult for the clinician to viewthe back of the eye.
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Which of the following routes of drug administration produces the MOST rapid absorption?
A. Inhalation
B. Intravenous
C. Oral
D. Rectal
E. Sublingual
The most important part of this question is the word "absorption." Intravenous introduction of a drug (choice B) does not involve absorption because the drug is injected directly into the circulation; therefore, this cannot be the correct answer. All of the remaining choices are modes are associated with absorption. The inhalation mode is the most rapid because of the great area of the absorptive surface and the close proximity of the blood.
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Tricyclic antidepressants
A. increase the antihypertensive effect of guanethidine.
B. have anticonvulsant activity.
C. should not be used in patients with glaucoma.
D. may increase oral absorption of levodopa.
E. are sometimes used as antiarrhythmics.
- C. should not be used in patients with glaucoma.
- In addition to blocking reuptake of NE and 5HT, pharmacodynamic actions of the tricyclic antidepressants include the blocking of peripheral adrenergic and muscarinic receptors the former resulting in postural hypotension and the latter, via mydriasis, exacerbating glaucoma. TCAs block the uptake of guanethidine into sympathetic nerve endings, decreasing its antihypertensive effects, and they may cause arrhythmias in overdose. They have no effect on the absorption of levodopa.
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After a myocardial infarction, a patient develops ventricular tachycardia. Physicians often treat this condition with the administration of which of the following medications?
A. Adenosine
B. Diltiazem
C. Esmolol
D. Lidocaine
E. None of the above
- D. Lidocaine
- Arrhythmias following myocardial infarct are best managed by administering IV lidocaine. Lidocaine acts on the ventricular muscle.
- Adenosine (choice A) is indicated for SVTs and nodal tachycardia. The primary action of both a beta-blocker (esmolol, choice C) and a calcium channel blocker (diltiazem, choice B) is at the AV node and is not very effective in the treatment of ventricular arrhythmias.
-
In the case of a drug that follows first-order elimination,
A. the rate of elimination is constant.
B. the elimination half-life varies with the
dose.
C. the volume of distribution varies with
dose.
D. the clearance varies with the dose.
E. the rate of elimination varies directly
with the dose.
- E. the rate of elimination varies directly with the dose.
- In first-order kinetics, the elimination rate of a drug is directly proportional to its plasma concentration, which in turn is proportional to the dose. Drugs that follow first-order elimination have constant elimination half-lives. Likewise, clearance (choice D)
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Which of the following glucocorticoids has the GREATEST relative anti-inflammatory effect?
A. Cortisone
B. Dexamethasone
C. Hydrocortisone
D. Prednisone
E. Ibuprofen
- B. Dexamethasone
- The use of glucocorticoids is indicated in the treatment of allergic reactions, as an anti-inflammatory, and in hormonally related conditions. It is important for the clinician to understand the relative potencies of each, along with the relative equivalent dosage.
- The relative anti-inflammatory potencies of these agents are as follows: dexamethasone, prednisone, hydrocortisone, cortisone. Ibuprofen (choice E) is an NSAID, not a glucocorticoid.
-
Which one of the following is LEAST likely to be an effect of histamine?
A. Bronchiolar constriction
B. Hypotension
C. Increased gastric secretion
D. Activation of type C pain fibers
E. Decreased capillary permeability
The correct answer is E. The activation of H1
receptors in bronchiolar smooth muscle leads to contraction, which leads to
bronchoconstriction, but in vascular smooth muscle relaxation could lead to
hypotension. H1 receptor activation increases the firing rate of the C-type
afferent pain fibers in the periphery, and activation to increased gastric acid
secretion. However, the release of histamine is associated with urticaria and
edema because of increased capillary permeability
- E. Decreased capillary permeability
- The activation of H1 receptors in bronchiolar smooth muscle leads to contraction, which leads to bronchoconstriction, but in vascular smooth muscle relaxation could lead to hypotension. H1 receptor activation increases the firing rate of the C-type afferent pain fibers in the periphery, and activation to increased gastric acid secretion. However, the release of histamine is associated with urticaria and edema because of increased capillary permeability
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Which of the following is a bacteriostatic antibiotic used in the treatment of an upper respiratory infection?
A. Penicillin
B. Azithromycin
C. Cefuroxime
D. Loracarbef
E. Ciprofloxacin
- B. Azithromycin (remember that it interferes with the cell wall synthesis, protein inhibition)
- Bacteriostatic antibiotics inhibit or retard the growth of microorganisms. Azithromycin is a macrolide antibiotic with bacteriostatic properties. The remaining answer choices are all bactericidal antibiotics. By definition, bactericidal antibiotics cause the death of the bacteria.
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Calcium channel antagonists
A. increase intracellular cAMP.
B. decrease myocardial contractility.
C. increase reactivation of Na+ channels.
D. decrease intracellular K+.
E. increase conduction velocity.
- B. decrease myocardial contractility
- Calcium channel antagonists decrease myocardial contractility by blocking the influx of Ca2+ ions through voltage-dependent L-type channels in the cardiac cell membrane. Calcium channel blockers do not have an effect on Na+channels (choice C), they do not change intracellular K+ levels (choice D), and they decrease conduction velocity (choice E).
-
Bending of the anesthetic syringe needle is recommended for
A. inferior alveolar nerve block.
B. posterior superior nerve block.
C. mental nerve block.
D. long buccal nerve block.
E. none of the above.
- E. none of the above
- For the safety of the patient, and especially for Board questions, a needle should never be bent. This prevents accidental needle breakage and also keeps the dentist's hands away from the needle. You may see dentists bending needles to get a better angle (especially in posterior superior alveolar nerve blocks), but it is not advisable.
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Thrombophlebitis is an adverse side effect after the intravenous administration of diazepam. Its cause is associated with which of the following compounds?
A. Ethyl alcohol
B. Saline solution
C. Benzoic acid
D. Propylene glycol
E. Sodium metabisulfite
- D. Propylene glycol
- When a medication is designed and produced for IV solution, it must be carried in a liquid vehicle that contains stabilizers. These stabilizers maintain the integrity of the drug as well as keep the components of the medication evenly dispersed throughout the liquid vehicle. One such compound is propylene glycol. This material can cause a severe tissue reaction and thrombophlebitis.
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Which of the following pairs of antifungals is used MOST often in topical treatment of candidiasis?
A. Nystatin and amphotericin B
B. Mycostatin and nystatin
C. Nystatin and clotrimazole
D. Clotrimazole and ketoconazole
E. Mycelex and clotrimazole
- C. Nystatin and clotrimazole
- Nystatin (Mycostatin) and clotrimazole (Mycelex) are two common antifungals used to treat candidiasis topically. Nystatin is usually a rinse, and Mycelex is in the form of troches (pastilles). Amphotericin is a powerful antifungal, usually given intravenously or intramuscularly (although a rinse exists). Ketoconazole is a systemic antifungal that can be given orally.
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Which of the following is used for treatment of athlete's foot?
A. Griseofulvin
B. Amphotericin B
C. Nystatin
D. Clotrimazole
E. Ampicillin
- A. Griseofulvin
- Griseofulvin is an antifungal used primarily against dermatophytes (skin fungi). It is notable for its method of operation-inhibition of microtubule synthesis. Nystatin (choice C) and clotrimazole (choice D) are topical antifungals often used for treating candidiasis. Amphotericin (choice B) is a (usually) systemic antifungal used for serious fungal infections caused by a variety of fungi. Ampicillin (choice E), an antibacterial, would be completely ineffective against fungal organisms.
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A systemic response to an overdose of lidocaine is noted first as
A. increased heartbeat.
B. irritability.
C. drowsiness.
D. increased blood pressure.
- B. irritability.
- The characteristic effect of lidocaine overdose is CNS excitation, followed by CNS depression. Therefore, the first sign is often nervousness or irritability. Increased blood pressure (choice D) or heart rate (choice A) is normally due to epinephrine, not lidocaine. Drowsiness (choice C) is more likely due to lidocaine, but is not noted first.
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Lorazepam can be safely used as a premedication for patients undergoing surgery without fear of excessive CNS depression because the drug is
A. excreted in an unchanged form.
B. actively secreted into the GI tract.
C. conjugated extrahepatically.
D. a selective anxiolytic devoid of CNS
depressant activity.
E. reversible with naloxone.
- C. conjugated extrahepatically.
- Most benzodiazepines are metabolized by liver cytochromes (P450). In a patient lacking liver function, benzodiazepines that are metabolized via extrahepatic conjugation are safer in terms of the possibility of excessive CNS depression. Lorazepam is metabolized, probably in the lungs, via glucuronidation. Although benzodiazepine actions can be reversed, the drug that acts as an antagonist is flumazenil, not naloxone.
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The major effect of anesthetic preventing nerve impulses from forming is due to blockage of
A. inward sodium current.
B. outward sodium current.
C. inward potassium current.
D. outward potassium current.
- A. inward sodium current.
- Local anesthetics block inward sodium current at the sodium channel (gate). Remember that first the sodium gates open, sodium rushes in, the potassium gates then open, and potassium rushes out. After this point, the original ionic distribution is restored before the next action potential.
-
Benzodiazepines are thought to cause sedative and/or anxiolytic effects by
A. increasing functional activity at GABA receptors
B. enhancing the actions of dopamine.
C. blocking the NMDA glutamate receptor subtype.
D. acting as a partial agonist at 5HT receptors.
E. facilitating GABA-mediated increases in chloride ion conductance.
- Facilitating GABA-mediated increases in chloride ion conductance.
- Benzodiazepine interacts with components of the GABA receptor-chloride ion channel macromolecular complex. Binding of BZs leads to an increase in the frequency of chloride ion channel opening elicited by the inhibitory transmitter GABA. Benzodiazepines do not act on GABAβ receptors; baclofen, a centrally acting muscle relaxant, is an agonist at these receptors. Buspirone, the selective anxiolytic, may be a partial agonist at 5HT receptors.
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Which antibiotic is no longer recommended for subacute bacterial endocarditis prophylaxis (as per 1997 American Heart Association guidelines)?
A. Azithromycin
B. Clarithromycin
C. Erythromycin
D. Clindamycin
E. Cephalexin
- C. Erythromycin
- Erythromycin is no longer on the recommended antibiotic list for subacute endocarditis prophylaxis. Its removal was due to unreliable absorption from gastric reactions. Alternatives for the penicillin-allergic patient include azithromycin (choice A), clarithromycin (choice B), clindamycin (choice D), cefadroxil, and cephalexin (choice E).
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Local anesthetic BEST enters the neuron when the anesthetic solution is
A. very acidic.
B. slightly acidic.
C. neutral.
D. slightly basic.
- C. neutral
- Prior to injection, the anesthetic solution in a carpule is in a slightly acidic and ionized form. When the solution is injected into the tissue, the slightly alkaline tissue fluids neutralize the anesthetic to the free base form. The alkalization of the anesthetic to the nonionized form improves the ability of the drug to enter into the neuron cell membrane. Once it is inside the neuron, it reionizes and attaches to the sodium channel to prevent sodium influx.
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Which antibiotic has high activity against anaerobes?
A. Penicillin VK
B. Penicillin G
C. Streptomycin
D. Erythromycin
E. Clindamycin
- E. Clindamycin
- Antibiotics with particular effectiveness against anaerobes include metronidazole, clindamycin, and second-generation cephalosporins. None of the other antibiotics listed are especially active against anaerobes. Streptomycin (choice C), specifically, is active only against aerobes.
-
Which of the following is MOST affected by ingesting antibiotic together with metallic ions from food?
A. Streptomycin
B. Erythromycin
C. Tetracycline
D. Amoxicillin
E. Clindamycin
- C. Tetracycline
- The tetracycline family of antibiotics (especially tetracycline) is affected by metallic ions. Specifically, when taken orally, these antibiotics may bind with metal ions in food (Ca+, Mg+, Fe2+) and be poorly absorbed. The general advice to patients is to avoid taking these antibiotics with meals.
-
Which antibiotic does NOT affect cell walls?
A. Methicillin
B. Cephalexin
C. Erythromycin
D. Vancomycin
E. Bacitracin
- C. Erythromycin
- Erythromycin acts on the 50S subunit of bacterial ribosomes. All penicillins (methicillin [choice A]) and cephalosporins (cephalexin, [choice B]) prevent NAG-NAM cross-linkages in bacterial cell walls. Both vancomycin (choice D) and bacitracin (choice E) are cell wall inhibitors, but neither works by inhibiting NAG-NAM cross-linkages
-
Which antibiotic is not given orally?
A. Amoxicillin
B. Streptomycin
C. Clarithromycin
D. Clindamycin
E. Metronidazole
- B. Streptomycin
- Streptomycin is an inhibitor of the 30S subunit of the bacterial ribosome and is in the aminoglycoside family of antibiotics with neomycin, gentamicin, and amikacin. It is effective only for aerobic infections and is sometimes used as an antimycobacterial. It is administered intravenously or intramuscularly, and it is sometimes used in combination with beta-lactam-type antibiotics.
- Tetracycline inhibits 30s as well
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