A client with bell's palsy tells the nurse that acetaminophen (Tylenol) is taken daily as prescribed by the physician. Which laboratory value would indicate a toxicity of the medication?

Correct Answer: A

Rationale: Acetaminophen (Tylenol) is primarily metabolized in the liver. Hepatotoxicity is a serious potential side effect of acetaminophen overdose or excessive use. One of the markers for liver damage due to acetaminophen toxicity is an elevated blood urea nitrogen (BUN) level. Normal BUN levels range from 7 to 20 mg/dl, and a level of 60 mg/dl indicates kidney dysfunction, which can result from liver damage caused by acetaminophen toxicity. Therefore, an elevated BUN level would indicate a toxicity of acetaminophen in this client with Bell's palsy who is taking acetaminophen daily. The other laboratory values mentioned are not specific markers for acetaminophen toxicity.

Correct Answer: B

Rationale: Valproate is classified as an anti-convulsant medication. It is commonly used to treat seizures, particularly in the management of epilepsy. Valproate works by affecting certain chemicals in the brain to control seizures and stabilize mood in some psychiatric conditions. It is not classified as an anti-diabetic, anti-ulcer agent, or anti-hypertensive medication.

Correct Answer: D

Rationale: Metformin belongs to the therapeutic classification of antidiabetic agents. It is commonly used to treat type 2 diabetes by helping to control blood sugar levels. Metformin works by decreasing glucose production in the liver and improving insulin sensitivity in the body's tissues. This helps the body use insulin more effectively, leading to better blood sugar control.

Correct Answer: D

Rationale: Antiemetic drugs are medications used to prevent and treat nausea and vomiting. Therefore, the main action of antiemetic drugs is to prevent vomiting, making option E the correct answer. Antiemetic drugs work by reducing or blocking the signals to the vomiting center in the brain, thus helping to alleviate the symptoms of nausea and prevent vomiting.

Correct Answer: D

Rationale: Histamine is a biogenic amine that acts as a neurotransmitter in the body. It is known to have several pharmacologic properties, such as the ability to reduce gastric secretion (Choice A), relaxation of vascular smooth muscle (Choice B), contraction of bronchi (Choice C), and production of pain and itch (Choice E). However, histamine does not have a direct effect on free nerve endings. Its effects on pain and itch are mediated through activation of specific histamine receptors on nerve cells and not through direct action on free nerve endings.