Comprehensive Nursing Pharmacology Q 20
A client with histoplasmosis has an order for ketoconazole (Nizoral). The nurse teaches the client to do which of the following while taking this medication?
A. Take the medication on an empty stomach.
B. Take the medication with an antacid.
C. Avoid exposure to sunlight.
D. Limit alcohol to 2 ounces per day.
Correct Answer: C. Avoid exposure to sunlight.
The client should be taught that ketoconazole is an antifungal medication. The client should also avoid exposure to sunlight because the medication increases photosensitivity. Ketoconazole has approval for use in the treatment of fungal infections of the skin and systemic fungal infections. These include blastomycosis, histoplasmosis, paracoccidioidomycosis, coccidioidomycosis, and chromomycosis. The most common use of ketoconazole for skin infections is that of tinea versicolor.
Option A: It should be taken with food or milk. Ketoconazole is available in tablet form and as a topical agent in creams, foams, and shampoos. It is also available in mixture products. Ketoconazole works as an antifungal agent by inhibiting the cytochrome P450 14?-demethylase enzyme. This enzyme is responsible for inhibiting the biosynthesis of triglycerides and phospholipids by fungi. More specifically, ketoconazole inhibits the synthesis of lanosterol, a necessary precursor for ergosterol biosynthesis. Ergosterol is needed to maintain the integrity of the membrane of fungi. Without ergosterol, the fluidity of the membrane increases, which in turn prevents the fungal growth.
Option B: Antacids should be avoided for 2 hours after it is taken because gastric acid is needed to activate the medication. The oral form of ketoconazole is used for systemic administration and must be taken at least two hours before any antacids. The high pH of the gastric contents would decrease absorption, so appropriate timing of administration is paramount to its absorption and subsequent efficacy. Adult and pediatric patients with achlorhydria should be given ketoconazole tablets with an acidic beverage to decrease pH and allow for optimal absorption.
Option D: The client should avoid concurrent use of alcohol because the medication is hepatotoxic. Ketoconazole is contraindicated in patients with acute or chronic liver disease due to its association with hepatotoxicity, which can be fatal. It is contraindicated in adrenal insufficiency because high doses of ketoconazole inhibit adrenocortical function. Due to its hepatoxic effects, patients taking oral ketoconazole should have their hepatic function monitored, which is through hepatic function tests such as aspartate transaminase (AST), alanine transaminase (ALT), alkaline phosphatase (ALP), bilirubin, albumin, and prothrombin time (PT).