NABP NABP Certifications NAPLEX Questions & Answers

• Question 141:

  Your patient is a 43-year-old male who is experiencing post-operative voiding difficulty after an elective inguinal hernia repair. His post void residual volume was 280 cc.

  Which of the following medications is the most appropriate choice of therapy for this patient?

  A. Bethanechol

  B. Oxybutynin

  C. Phenylephrine

  D. Finasteride

  E. Imipramine

  Correct Answer: A

  The patient is experiencing a common complication of low abdominal surgery. Post-operative urinary retention occurs in almost 25% of patients after low abdominal surgical procedures. A normal post-void residual volume is less than 50 cc or urine. The effects of anesthesia and analgesia both contribute to bladder distension, decreased micturition reflex, reduction of contractility of the detrusor muscle of the bladder, and incomplete voiding. The detrusor muscle of the bladder is stimulated to contract by muscarinic cholinergic agonists. Bethanechol is a muscarinic agonist and is frequently used in this setting to improve bladder emptying. Finasteride is a drug that is a 5 alpha reductase inhibitor indicated for use in patients with bladder outlet obstruction as a result of prostatic hypertrophy. The inhibition of 5 alpha reductase decreases local conversion of testosterone to dihydrotestosterone in the prostate gland, which results in gradual shrinkage over a period of six to twelve months. Phenylephrine is an alpha-adrenergic agonist that is selective for alpha-1 receptors. Activation of the alpha 1 receptors in the bladder results in contraction of the trigone muscle and sphincter. This promotes urinary retention. Oxybutynin is an antimuscarinic agent that is useful for treatment of urge incontinence, and would have a detrimental effect on this patient's bladder disorder. Imipramine is a medication with anticholinergic properties that would also cause worsening of the patient's condition. Take home message: Post-operative urinary retention with concomitant incomplete voiding is a complication that results from a decreased micturition reflex, increased vesical sphincter tone, or decreased contractility of the detrusor muscle of the bladder. It can be successfully treated with a muscarinic agonist, such as bethanechol, or with an alpha-1 adrenergic antagonist.

• Question 142:

  A 27-year-old female with ovarian cancer is undergoing chemotherapy. She develops subsequent renal failure.

  Which of the following drugs is most likely responsible for this?

  A. Cyclophosphamide

  B. Bleomycin

  C. Cisplatin

  D. Vinblastine

  E. Vincristine

  Correct Answer: C

  Cisplatin. All chemotherapeutics have similar generalized side effects related to their effects on rapidly growing cells. These include hair loss, nausea, and fatigue. However, many chemotherapeutics have unique toxicities as well which are often tested. Cisplatin (C) is notable for its nephrotoxicity and ototoxicity. Cyclophosphamide (A) is known to cause hemorrhagic cystitis. This is a distinct process from nephrotoxicity. The most noteworthy side effect of bleomycin (B) is pulmonary toxicity that can lead to pulmonary fibrosis. Vinblastine (D) is known for bone marrow suppression. Vincristine (E) causes neuropathy.

• Question 143:

  A 55-year-old female is receiving chemotherapy for metastatic carcinoma. She threatens to stop her treatment because of severe nausea and vomiting. The oncologist plans to use prochlorperazine to reduce the nausea and vomiting associated with chemotherapeutic agents. What is the mechanism of action of prochlorperazine?

  A. Serotonin 5-HT3 antagonist

  B. Blocking dopamine receptors

  C. Cannabinoids related

  D. Blockage of prostaglandins

  E. H2 receptor antagonist

  Correct Answer: B

  B: A variety of drugs have been found to be of some value in the prevention and treatment of vomiting, especially cancer chemotherapy-induced vomiting. With the exception of thioridazine, most of the neuroleptic drugs have antiemetic effects that are mediated by blocking D2 dopaminergic receptors of the chemoreceptor trigger zone of the medulla. Phenothiazines, such as prochlorperazine, were the first drugs shown to be effective antiemetic agents and act by blocking dopamine receptors. They are effective against low to moderately emetogenic chemotherapeutic agents (for example, fluorouracil and doxorubicin). Although increasing the dose improves antiemetic activity, side effects, including hypotension and restlessness, are dose limiting. Other adverse reactions include extrapyramidal symptom and sedation. A: Serotonin 5-HT3 antagonist is incorrect. The specific antagonists of the 5-HT3 receptor, ondansetron and granisetron, selectively block 5-HT3 receptors in the periphery and in the brain (chemoreceptor trigger zone). C: Cannabinoids related is incorrect. Cannabinoids are marijuana derivatives including dronabinol and nabilone and are effective against moderately emetogenic chemotherapy. However, they are seldom first-line antiemetics because of serious side effects. D: Blockage of prostaglandins is incorrect. Dexamethasone and methylprednisolone used alone are effective against mildly to moderately emetogenic chemotherapy. Their antiemetic mechanism is not known, but it may involve blockade of prostaglandins. E: H2 receptor antagonist is incorrect. Antagonists of histamine H2 receptor block the action of histamine at all H2 receptors; their chief clinical use is as inhibitors of gastric acid secretion.

• Question 144:

  Which of the following is a side effect of valproic acid?

  A. Gingival hyperplasia

  B. Pancreatitis

  C. Kidney stones

  D. Weight loss

  E. Euphoria

  Correct Answer: B

  Pancreatitis is one of the most serious adverse effects that can be caused by valproic acid. Gingival hyperplasia is a side effect of Phenytoin. Kidney stones and weight loss can be a side effect of zonisamide or topiramate.

• Question 145:

  Which of the following illnesses is an example of a type III hypersensitivity reaction?

  A. Lupus

  B. Graves disease

  C. Hashiomoto's thyroiditis

  D. Allergic rhinitis

  E. Myasthenia gravis

  Correct Answer: A

  A type III hypersensitivity reaction is mediated by immune complex deposition. In lupus, auto-antibodies are formed and these complexes are deposited in other tissues, especially in the kidneys, skin, and joints. Graves disease and myasthenia gravis are examples of type II but in some classification systems they are called type V reactions. The auto-antibodies created in Graves attack TSH receptors in the thyroid, whereas in Myasthenia the target is the acetylcholine receptor. Hashimoto's thyroiditis is usually considered an example of a combination of type II and IV reactions, as T cells are directed at thyroid antigens and antibodies are also produced. Allergic rhinitis is a classic example of a type I, IgE mediated reaction.

• Question 146:

  You prescribe doxepin to a 37-year-old woman to treat neurotic excoriations on her arms. The patient is concerned about the side effects of this drug. Which of the following is not a side effect of doxepin:

  A. Xerostomia

  B. Liver toxicity

  C. Somnolence

  D. Urinary retention

  E. Constipation

  Correct Answer: B

  A,C,D,E ?False ?Doxepin is a tricyclic antidepressant with H1 and H2 antihistamine activity. Side effects include sedation and anticholinergic effects (dry mouth, urinary retention, and constipation). Although extensively metabolized by the liver and excreted by the kidney, liver toxicity is very rare. Nephrotoxicity, on the other hand, is a well-known serious adverse effect of long term doxepin use.

• Question 147:

  A patient with multibacillary leprosy is on dapsone, clofazimine, and rifampin. Which of the following is true regarding the mechanism of action of the medications listed?

  A. Dapsone is bacteriostatic because of its inhibitory effects on dihydrofolate reductase

  B. Dapsone is bacteriostatic because of its inhibitory effects on myeloperoxidase

  C. Clofazimine is bactericidal by directly inhibiting bacterial DNA polymerase

  D. Rifampin is bacteriostatic by inhibiting RNA synthesis by blocking DNA-dependent RNA polymerase

  E. Rifampin is bactericidal by inhibiting RNA synthesis by blocking DNA-dependent RNA polymerase

  Correct Answer: E

  A, B ?false ?dapsone inhibits bacterial synthesis of dihydrofolic acid, via competition with paraaminobenzoate for the active site of dihydropteroate synthetase. Dapsone is both bacteriostatic and weakly bactericidal against M. leprae. Neither of the listed mechanisms are the cause of these effects. C ? False ?A substance with both anti-leprosy and anti-inflammatory activity, clofazimine is weakly bactericidal against M. leprae by binding to the guanine bases of bacterial DNA, not DNA polymerase directly. D ? False ?See below. E ?True ?Rifampin is bactericidal by inhibiting RNA synthesis by blocking DNA-dependent RNA polymerase.

• Question 148:

  Your patient is a 58-year-old male who presents with onset of severe substernal chest pain and shortness of breath. An ECG reveals an acute STEMI, and he is on his way to the cardiac catheterization suite for percutaneous coronary intervention. Which of the following drugs used in acute coronary syndromes treated with PCI must undergo oxidation by hepatic P450 enzymes to an active form?

  A. Clopidogrel

  B. Ticlopidine

  C. Eptifibatide

  D. Aspirin

  E. Warfarin

  Correct Answer: A

  Clopidogrel and ticlopidine are ADP receptor pathway inhibitors. The irreversible inhibition of the ADP-dependent pathway of platelet activation is thought to be the result of covalent modification and inactivation of the platelet P2Y ADP receptor. This receptor is coupled to the inhibition of adenylyl cyclase. Both drugs are prodrugs and undergo conversion to active metabolites in the liver. However, clopidogrel must undergo oxidation by hepatic P450 enzymes to its active form. This is significant because many drugs are metabolized the hepatic P450 enzymes, including statins, and clopidogrel may interact with these medications. Clopidogrel is a second-generation thienopyridine and ticlopidine is a first- generation thienopyridine. Both drugs are indicated in combination with aspirin to prevent stent thrombosis. Eptifibatide is a GPIIb-IIIa receptor antagonist that is used to treat unstable angina and non-ST segment elevation myocardial infarction. Eptifibatide is also used to reduce ischemic events in patients who are undergoing percutaneous coronary intervention. The drug is a synthetic peptide that directly antagonizes the GPIIb-IIIa receptor on the platelet. Aspirin is an antiplatelet drug that works by inhibition of synthesis of prostaglandins. Prostaglandin G2 is the result of a synthesis pathway that is activated by platelets and endothelial cells, and results in localized vasoconstriction and induction of platelet aggregation, as well as causing release of platelet granules. Warfarin is an anticoagulant that acts on vitamin K-dependent reactions in the coagulation pathway. Vitamin K is necessary for hepatic synthesis of coagulation factors II, VII, IX and X, protein C and protein S. Vitamin K-dependent carboxylation is necessary for induction of enzymatic activity of these coagulation factors. Take-home message: Clopidogrel, a second-generation thienopyridine ADP receptor pathway inhibitor, is indicated in combination with aspirin to prevent stent thrombosis in patients who undergo percutaneous coronary intervention after myocardial infarction. Clopidogrel is a prodrug that must undergo oxidation by hepatic P450 enzymes, and therefore may affect the activity of statins and other drugs dependent on the hepatic P450 enzymes.

• Question 149:

  Which of the following is true regarding extent of absorption of drugs?

  A. After oral ingestion of drugs, the absorption of drug may be incomplete

  B. Drugs which are too lipophilic cannot cross the lipid cell membrane

  C. Drugs which are too hydrophilic are not soluble enough to cross the water layer adjacent to the cell

  D. P-glycoprotein is an efflux transporter which is present in the enterocytes and it enhances the absorption of drug

  E. Grape juice activates P-glycoprotein leading to substantial inhibition of absorption of drugs

  Correct Answer: A

  It is not necessary that all the drugs get completely absorbed after oral administration. Most of them are incompletely absorbed. The extent of absorption varies from 5 to less than 100 % with oral ingestion of drugs. Drugs which are too hydrophilic like atenolol are incompletely absorbed because the drug cannot cross the lipid membrane due to high hydrophilic nature of the drug. Similarly, drugs which are too lipophilic like acyclovir are not soluble enough to cross the water layer adjacent to the cell. P-glycoprotein is an efflux transporter which is present in the enterocytes and it inhibits absorption of drug. It is also known as export transporter or reverse transporter. It has many drugs as its substrate. Grape juice in fact inhibits P-glycoprotein in the intestine thereby decreasing the efflux of drug from the cells by Pglycoprotein. Thus ingestion of grape juice may lead to significantly increased absorption of the drug.

• Question 150:

  What is the best anti-thyroid regimen in a pregnant woman who has clinically significant hyperthyroidism?

  A. Stop treatment and resume post-partum

  B. Propylthiouracil

  C. Methimazole

  D. Propylthiouracil first trimester followed by methimazole for the remainder of pregnancy

  E. Methimazole first trimester followed by propylthiouracil for the remainder of pregnancy

  Correct Answer: D

  Propylthiouracil (PTU) is recommended for treatment of hyperthyroidism in women who are in their first trimester of pregnancy by the American Thyroid Association (ATA). Methimazole has been associated with congenital malformations including aplasia cutis in rare cases and thus it is not recommended in the first trimester. The ATA recommends switching to methimazole once in the second trimester as there is a risk of liver injury associated with the use of PTU.