Phenytoin has a narrow therapeutic index.
The nurse recognizes that this characteristic indicates which of these?

The safe and the toxic plasma levels of the drug are very close to each other.

The phenytoin has a low chance of being effective.

There is no difference between safe and toxic plasma levels.

A very small dosage can result in the desired therapeutic effect.

Answer and Explanation

The Correct Answer is A

Choice A rationale:

Phenytoin is an anticonvulsant drug used in the prophylaxis and control of various types of seizures. It has a narrow therapeutic index, which means that the safe and toxic plasma levels of the drug are very close to each other. This characteristic makes the dosing of phenytoin challenging, as even small deviations from the recommended therapeutic range can lead to suboptimal treatment or adverse effects. Therapeutic effect without clinical signs of toxicity occurs more often with serum total concentrations between 10 and 20 mcg/mL34. Therefore, clinicians are advised to initiate therapeutic drug monitoring in patients who require phenytoin.

Choice B rationale:

The statement that phenytoin has a low chance of being effective is incorrect. Phenytoin is a widely used and effective anticonvulsant. It works by slowing down impulses in the brain that cause seizures. It is used to control seizures but does not treat all types of seizures. The effectiveness of phenytoin is not determined by its narrow therapeutic index but by its pharmacological action in the brain.

Choice C rationale:

The assertion that there is no difference between safe and toxic plasma levels of phenytoin is incorrect. There is indeed a difference between the safe (therapeutic) and toxic levels of phenytoin. The therapeutic range for phenytoin is typically between 10 and 20 mcg/mL34. Levels above this range can lead to toxicity, while levels below this range may not provide the desired therapeutic effect.

Choice D rationale:

The statement that a very small dosage of phenytoin can result in the desired therapeutic effect is not entirely accurate. While it’s true that phenytoin is effective in controlling seizures, the dosage required to achieve this effect is not necessarily “very small”. The usual adult dose for seizures is 100 mg orally 3 times a day. The dosage may need to be adjusted based on individual patient factors and response to therapy. Therefore, it’s not accurate to generalize that a “very small” dosage will result in the desired therapeutic effect for all patients.

Nursing Test Bank

Quiz #1: RN Exams Pharmacology Exams Quiz #2: RN Exams Medical-Surgical Exams Quiz #3: RN Exams Fundamentals Exams Quiz #4: RN Exams Maternal-Newborn Exams Quiz #5: RN Exams Anatomy and Physiology Exams Quiz #6: RN Exams Obstetrics and Pediatrics Exams Quiz #7: RN Exams Fluid and Electrolytes Exams Quiz #8: RN Exams Community Health Exams Quiz #9: RN Exams Promoting Health across the lifespan Exams Quiz #10: RN Exams Multidimensional care Exams

Get 100+ Naxlex Exit Exams for $79 Try Naxlex NCLEX-RN (14 Day Free-Trial)

Naxlex Comprehensive Predictor Exams

Quiz #1: Naxlex RN Comprehensive online practice 2019 B with NGN Quiz #2: Naxlex RN Comprehensive Predictor 2023 Quiz #3: Naxlex RN Comprehensive Predictor 2023 Exit Exam A Quiz #4: Naxlex HESI Exit LPN Exam Quiz #5: Naxlex PN Comprehensive Predictor PN 2020 Quiz #6: Naxlex VATI PN Comprehensive Predictor 2020 Quiz #8: Naxlex PN Comprehensive Predictor 2023 - Exam 1 Quiz #10: Naxlex HESI PN Exit exam Quiz #11: Naxlex HESI PN EXIT Exam 2

Free Nursing Study Resources

Correct Answer is A

Explanation

Choice A rationale:

Rifampin Rifampin is an antitubercular drug that is effective against all strains of Mycobacterium tuberculosis. It works by inhibiting the synthesis of RNA in the bacteria, preventing them from reproducing. However, it does not typically cause a decrease in visual acuity.

Choice B rationale:

Ethambutol Ethambutol is an antitubercular drug that can cause ocular toxicity in the form of visual field changes. It is known to induce toxic optic neuropathy, which is quite common and can lead to a decrease in visual acuity. Patients on Ethambutol therapy are advised to report any changes in visual acuity or eye discomfort immediately to their healthcare provider.

Choice C rationale:

Streptomycin Streptomycin is an aminoglycoside antibiotic used in the treatment of tuberculosis. It works by inhibiting protein synthesis in bacteria. While it can cause side effects such as ototoxicity and nephrotoxicity, it is not typically associated with a decrease in visual acuity.

Choice D rationale:

Isoniazid Isoniazid is a first-line antitubercular drug that works by inhibiting the synthesis of mycolic acids in the cell wall of Mycobacterium tuberculosis. While it can cause peripheral neuropathy, it is not typically associated with a decrease in visual acuity.

A. “I haven’t had anything to eat or drink since last night.” B. “The last time I voided it was painful.” C. “I took my metformin before breakfast.” D. “I took a laxative yesterday.”

Correct Answer is C

Explanation

Choice A rationale:

The client stating, “I haven’t had anything to eat or drink since last night” is not a cause for concern. This is because patients are often advised to fast before undergoing certain medical procedures or tests, including an intravenous pyelogram (IVP).

Fasting helps to ensure that the test results are accurate and not influenced by recent food or drink consumption.

Choice B rationale:

The client expressing that “The last time I voided it was painful” could be related to their recurrent kidney stones. Kidney stones can cause discomfort or pain during urination. However, this statement does not necessarily require additional data collection in the context of an IVP. The pain could be a symptom of the kidney stones rather than a contraindication for the IVP1.

Choice C rationale:

The statement “I took my metformin before breakfast” is of concern. Metformin is a medication used to treat type 2 diabetes. It is important for the nurse to collect additional data about this statement because metformin can potentially interact with the iodine-based contrast dye used in an IVP. This interaction can increase the risk of lactic acidosis, a serious and potentially lifethreatening condition. Therefore, patients are often advised to stop taking metformin before and for a couple of days after having an IVP12. Choice D rationale:

The client mentioning, “I took a laxative yesterday” is not necessarily alarming. Laxatives are often used before an IVP to clear the bowels, which helps to ensure clear images during the procedure. Therefore, this statement does not require additional data collection in the context of an IVP1.

View Question and Answer

Whether you are a student looking to ace your exams or a practicing nurse seeking to enhance your expertise , our nursing education contents will empower you with the confidence and competence to make a difference in the lives of patients and become a respected leader in the healthcare field.

Visit Naxlex, invest in your future and unlock endless possibilities with our unparalleled nursing education contents today

Phenytoin has a narrow therapeutic index. The nurse recognizes that this characteristic indicates which of these?

Nursing Test Bank

Naxlex Comprehensive Predictor Exams

When monitoring patients on antitubercular drug therapy, the nurse knows that which drug may cause a decrease in visual acuity?

Correct Answer is A

Explanation

A nurse is caring for a client who has recurrent kidney stones and a history of diabetes mellitus. The client is scheduled for an intravenous Pyelogram (IVP). The nurse should collect additional data about which of the following statements made by the client?

Correct Answer is C

Explanation

During morning medication administration, the nurse discovered an error on the electronic Medication Administration Record (MAR) before the medication was given. What is the appropriate action for this “near-miss”?

During antibiotic therapy, the nurse will monitor closely for signs and symptoms of a hypersensitivity reaction. Which of these assessment findings may be an indication of a hypersensitivity reaction? (Select all that apply.)

A nurse is reinforcing teaching with a client who has type 2 diabetes mellitus. The nurse determines that teaching has been effective when the client identifies which of the following manifestations of hypoglycemia? (Select all that apply.)

A nurse is documenting an 8-hour intake and output (I&O) record for a patient who consumed 4 oz of juice, 6 oz of tea, a 100 mL cup of soda, an IV bolus of 150 mL, and 8 oz of broth. How many mL of intake should the nurse record on the patient’s chart?

A nurse is caring for a client who has diabetes insipidus. Which of the following findings should the nurse expect?

A nurse is reinforcing teaching with a client who has diabetes mellitus about the manifestations of hypoglycemia. Which of the following statements by the client indicates an understanding of the teaching?

A young adult calls the clinic to ask for a prescription for a new flu drug. He says he has had the flu for almost 4 days and just heard about a drug that can reduce the symptoms. What is the nurse’s best response to his request?

Phenytoin has a narrow therapeutic index.
The nurse recognizes that this characteristic indicates which of these?