NAPLEX Online Practice Questions and Answers

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.

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.

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.

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.

Correct Answer: A

Correct Answer: C

It is reasonable to add triglyceride-lowering medications such as fibrates or niacin to prevent pancreatitis in those with triglyceride levels >500 mg/dL, which applies to this patient as his TG level is 640 mg/dL . C. is wrong because gemfibrozil should not be initiated in patients on statin therapy because of an increased risk for muscle symptoms and rhabdomyolysis. Fenofibrate may be considered concomitantly with a low-or moderate- intensity statin when triglycerides are above 500 mg/dL,2, however he is on a high intensity statin therapy. For niacin, the IR dose should start at 100 mg TID2 and niacin does not lower triglyceride levels as much as fibrate do.4 Fenofibrates are dose adjusted for renal function lower than 60 mL/min to 54 mg/mL, so this dose is appropriate for this patient because of his renal function being above 60 mL/min. The best option is fenofibrate 162 mg daily, but this needs to be monitored for any symptoms of muscle pain exhibited by the patient, especially as the patient is at a higher risk due to being a diabetic. Fish oil is not a first line agent to treat hypertriglyceridemia.

Reference: http://circ.ahajournals.org/content/129/25_suppl_2/S1

Correct Answer: B

Incidence rate = New reported cases / summed person-years of observation (avg population during time interval) Prevalence = Cases in a population in a given time period / total population at that time.

Reference: https://www.cdc.gov/ophss/csels/dsepd/ss1978/lesson3/section2.html http://www.healthknowledge.org.uk/public-health-textbook/research-methods/1a-epidemiology/numeratorsdenominators-populations

Correct Answer: C

A, B, C. Hepatotoxicity, including hepatic failure, has been fatal and may more commonly occur in the first 6 months of treatment. Valproic acid and its analogs are contraindicated in patients with known urea cycle disorders. Patients with urea cycle disorders have a genetic enzyme defect leading to an impaired ability to produce urea. Hyperammonemic encephalopathy has been reported following initiation of valproate therapy. Because of, inhibition of the secondary phase of platelet aggregation, and abnormal coagulation parameters complete blood counts and coagulation tests are recommended before initiating valproic acid therapy and at periodic intervals.

Correct Answer: D

Pregabalin is the active ingredient of the medicine Lyrica; a drug used to treat epilepsy, neuropathic pain, fibromyalgia and generalized anxiety disorder (GAD).

Correct Answer: A

Benign prostatic hyperplasia (BPH) is an example of postrenal acute kidney injury (AKI). Postrenal AKI, as the name suggests, involves an effect `post' or `beyond' the kidney, to problems that emerge downstream from the kidney. BPH is one such example of that. Other examples include kidney stones, bladder stones and bladder cancer.