NABP NAPLEX Exam
North American Pharmacist Licensure Examination (Page 10 )

Updated On: 9-Feb-2026

An 11-year-old male presents with his mother to your clinic with 5 days of frequent diarrhea, occasionally with streaks of blood mixed in. Stool cultures are pending, but preliminary stool samples demonstrate fecal WBC and RBC. Assuming the patient is stable enough for outpatient management, what would be the optimal treatment assuming the underlying pathogen is Shigella?

  1. Oral Erythromycin
  2. Oral Metronidazole
  3. Oral Vancomycin
  4. An oral quinolone
  5. Oral TMP-SMX

Answer(s): E

Explanation:

Correct: E. Shigella can cause bloody diarrhea, and frequently affects young children and institutionalized patients. The pathogen is highly contagious, and is spread via fecal-oral transmission. The pathogen can lead to severe dehydration, and even cause febrile seizures in young patients. For clinically stable patients who can be managed via outpatient therapy, the optimal treatment is via PO TMP-SMX to decrease the risk of person-to-person transmission. Choice A – Erythromycin is the first line treatment for bloody diarrhea caused by the pathogen campylobacter. However, for the purposes of decreasing transmissibility of suspected Shigella, TMP-SMX remains the mainstay of therapy. Choices B + C – Oral metronidazole and oral vancomycin can both be used in the treatment of Clostridium deficile. Alternatively, intravenous metronidazole can be given if the patient is unable to tolerate oral medications. Choice D – Oral quinolones can be used in cases of bloody diarrhea in which salmonella is the suspected pathogen. Salmonella is caused by the ingestion of contaminated poultry and/or eggs, and can ultimately lead to bacteremia in 5-10% of cases.



A 22-year-old woman adopted a cat. Shortly thereafter, she developed itchy eyes and persistent rhinorrhea. She was clearly allergic to the pet, but desperately wanted to keep it. She tried taking diphenhydramine, but it had intolerable side effects.
Which of the following is a common effect of this type of medication?

  1. Decreased intraocular pressure
  2. Bradycardia
  3. Xerostomia
  4. Diarrhea
  5. Excessive sweating

Answer(s): C

Explanation:

Diphenhydramine possesses anticholinergic properties. Xerostomia, or dry mouth, is a common side effect of anti-cholinergic medications, due to anti-muscarinic, parasympatholytic effects. Other adverse reactions may include: • Mydriasis with blurred vision, photophobia • Urinary retention • Constipation • Anhidrosis • Hyperthermia • Tachycardia • Altered mental status
A commonly referenced mnemonic for anti-cholinergic toxicity is “mad as a hatter, red as a beet, dry as a bone, hot as a hare, blind as a bat” to reflect confusion, flushing, dry mouth, hyperthermia and mydriasis, respectively.



An 18-year-old female is referred to a dermatologist for treatment of severe acne vulgaris. The dermatologist wants to start her on tetracycline.
What test should the patient have prior to starting treatment?

  1. Pregnancy test
  2. Chest X-ray
  3. Complete blood count
  4. Liver function tests
  5. Creatine kinase

Answer(s): A

Explanation:

Pregnancy test. Tetracyclines are effective in the treatment of severe cases of acne. They are however teratogenic. As such, it is imperative to make sure female patients are not pregnant prior to starting this medication. In many instances patients are started on concurrent birth control to mitigate this risk even further.
A chest x-ray (B) is an important exam to obtain prior to starting drugs which have pulmonary toxicity as a side effect such as amiodarone. A complete blood count (C) would be useful prior to starting a medication that causes anemia, such as immunosuppressive and chemotherapeutic agents. Liver function tests (D) are important to establish as a baseline prior to starting anti-mycobacterial agents. Creatine kinase levels (E) are used to establish as a baseline prior to starting statins.



A 7-year-old boy has been suffering from influenza and had been given a drug by his father to decrease his high fever. A few hours later, his father brought him to the emergency room in a comatose state with a papulovesicular rash all over the body, moderate hepatomegaly, and asterixis. Laboratory studies reveal elevated levels of blood ammonia, AST, ALT, and PT. CT scan findings are suggestive for generalized cerebral edema.
The drug the father gave his son is most likely which of the following drugs?

  1. Aspirin
  2. Acetaminophen
  3. Indomethacin
  4. Mefenamic acid
  5. Diclofenac

Answer(s): A

Explanation:

A: The syndrome is an acute noninflammatory encephalopathy with hepatic failure. Although the etiology of Reye's syndrome is unknown, the condition typically follows viral illness, particularly upper respiratory tract infection (URTI), influenza, varicella, or gastroenteritis, and is associated with aspirin use during the illness. A dramatic decrease in aspirin use in children has made Reye's syndrome rare. High index of suspicion is critical for diagnosis. Consider Reye's syndrome in any child with vomiting and altered mental status. Pathogenesis is unclear, but it typically involves mitochondrial dysfunction in a viral-infected, sensitized host, usually with exposure to mitochondrial toxins (e.g., salicylates, in >80% of cases). Individuals with low levels of urea cycle enzymes are also at increased risk. Mortality has fallen from 50% to less than 20% as a result of earlier diagnosis, recognition of milder cases, and more aggressive therapy. Signs and symptoms of Reye's syndrome include protracted vomiting, with or without significant dehydration, encephalopathy in afebrile patients with minimal or absent jaundice, and hepatomegaly in 50% of patients. Antiemetics may mask early symptoms. Liver function tests reveal elevation of ammonia levels to as much as 1.5 times normal (up to 1200g/dL) 24-48 hours after the onset of mental status changes; this is the most frequent laboratory abnormality. Transaminases (ALT and AST) increase to 3 times normal. Histologic changes include: hepatocyte cytoplasmic fatty vacuolization, astrocyte edema, loss of neurons, and edema and fatty degeneration in proximal lobules. The American Academy of Pediatrics Committee on Infectious Disease recommends that salicylate not be given to children with chicken pox or influenza B. B: Acetaminophen is incorrect. Acetaminophen acts by prostaglandin synthesis in the CNS, and this explain its antipyretic and analgesic properties, which account for its weak anti- inflammatory activity. Acetaminophen is a suitable substitute for the analgesic andantipyretic effects of aspirin in those patients with gastric complaints and to avoid Reye's syndrome in children. C: Indomethacin is incorrect. Indomethacin is more potent than aspirin as an anti-inflammatory agent (NSAID), but it is inferior to the salicylates at doses tolerated by rheumatoid arthritis patients. D: Mefenamic acid is incorrect. Mefenamic acid has no advantage over the other NSAIDS as anti- inflammatory agents. The side effects of mefenamic acid, such as diarrhea, can be severe and associated with inflammation of the bowel. E: Diclofenac is incorrect. Diclofenac is approved for long-term use in the treatment of rheumatoid arthritis, osteoarthritis, and ankylosing spondylitis.



A 50-year-old female has been receiving a diuretic for the treatment of essential hypertension. This drug acts by increasing the calcium content of urine and is the drug of choice for reducing acute pulmonary edema in congestive heart failure. Its side effects include ototoxicity and hyperuricemia. What is the most likely mechanism of action of this drug?

  1. Aldosterone receptor antagonist
  2. Inhibition of the Na/K/2Cl cotransporter
  3. Inhibition of carbonic anhydrase
  4. Acts as osmotic diuretic
  5. Blocking of the NACL cotransporter

Answer(s): B

Explanation:

B: Loop diuretics inhibit the Na/K/2Cl cotransporter of the luminal membrane in the ascending limb of the loop of Henle. Therefore, reabsorption of Na, K, and CL is decreased. The loop diuretics are the most efficacious of the diuretic drugs because the ascending limb accounts for the reabsorption of 25–30 % of filtered NaCl and downstream sites are not able to compensate for this increased Na load. Loop diuretics are the drugs of choice for reducing acute pulmonary edema in congestive heart failure. Loop diuretics act promptly, even among patients who have poor function or who have not responded to thiazides or other diuretics. Adverse side effects include ototoxicity, particularly when used in conjunction with the aminoglycoside antibiotics. Furosemide and ethacrynic acid compete with uric acid for the renal and biliary secretary system, thus blocking its secretion, and thereby causing or exacerbating gouty attacks. A: Aldosterone receptor antagonist is incorrect. Spironolactone is a synthetic aldosterone antagonist that competes with aldosterone for intracellular cytoplasmic receptor sites. Because spironolactone chemically resembles some of the sex steroids, it does have minimal hormonal activity and may induce gynecomastia in males and menstrual irregularities in females. C: Inhibition of carbonic anhydrase is incorrect. Acetazolamide inhibits carbonic anhydrase, which is located intracellulary and on the apical membrane of the proximal tubular epithelium. The decreased ability to exchange NA for H in the presence of acetazolamide results in a mild diuresis. The adverse side effects of acetazolamide include metabolic acidosis (mild), potassium depletion, renal stone formation, drowsiness, and paresthesia. D: Acts as osmotic diuretic is incorrect. A number of simple, hydrophilic, chemical substances that are filtered through the glomerulus, such as mannitol and urea, result in some degree of diuresis. This is due to their ability to carry water with them into tubular fluid. Osmotic diuretics are a mainstay of treatment for patients with increased intracranial pressure or acute renal failure due to shock, drug toxicities, or trauma. E: Blocking of the NaCl cotransporter is incorrect. The thiazide derivatives act mainly in the distal tubule to decrease the reabsorption of Na by inhibition of an Na/Cl cotransporter on the luminal membrane. As a result, these drugs increase the concentration of NA and CL in the tubular fluid. Hypokalemia is the most frequent problem encountered with the thiazide diuretics and can predispose patients on digitalis to ventricular arrhythmias. Thiazides increase serum uric acid by decreasing the amount of acid excreted by the organic acid secretory system. The thiazides inhibit the secretion of calcium, sometimes leading to elevated levels of Ca in the blood.






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