Comprehensive Nursing Pharmacology Q 26
A nurse has taught a client taking a xanthine bronchodilator about beverages to avoid. The nurse determines that the client understands the information if the client chooses which of the following beverages from the dietary menu?
A. Chocolate milk
B. Cranberry juice
C. Coffee
D. Cola
Correct Answer: B. Cranberry juice
Cola, coffee, and chocolate contain xanthine and should be avoided by the client taking a xanthine bronchodilator. This could lead to an increased incidence of cardiovascular and central nervous system side effects that can occur with the use of these types of bronchodilators. Methylxanthines are a purine-derived group of pharmacologic agents that have clinical use because of their bronchodilatory and stimulatory effects. This class includes several drugs, including the world’s most widely used caffeine. The FDA has approved the use of several methylxanthine derivatives for the treatment of reversible airway obstruction diseases such as chronic bronchitis, emphysema, and asthma.
Option A: Methylxanthines are well-documented competitive inhibitors of the enzyme phosphodiesterase (isoenzyme types III and IV), nonselective antagonists of adenosine receptors (subtypes A1, A2, and A3), and activators of histone deacetylase (isoenzyme type II), however, the complete mechanism of action of methylxanthines is not known.
Option C: Methylxanthines are available as tablets, extended-release tablets, and an oral solution. When administered orally, the drug is absorbed rapidly. However, broadly fluctuating plasma drug concentrations are a well-documented disadvantage to this route of administration. Despite the development of extended-release formulations, variability in plasma drug levels has led oral administration of methylxanthines to fall out of favor clinically.
Option D: Methylxanthine toxicity can present with any of the following symptoms: intractable nausea, cardiac arrhythmias, rhabdomyolysis, seizures, or cardiac arrest. Charcoal or sorbitol may be administered to reduce further GI absorption of the drug (however, this is only effective with oral dosing of the drug). There is some evidence to suggest that beta-blocker administration may decrease cardiac adverse events in patients with methylxanthine toxicity. Intravenous administration of benzodiazepines may be employed to abort seizure activity induced by toxicity.