Comprehensive Nursing Pharmacology Q 44
A client with advanced cirrhosis of the liver is not tolerating protein well, as evidenced by abnormal laboratory values. The nurse anticipates that which of the following medications will be prescribed for the client?
A. lactulose (Chronulac)
B. ethacrynic acid (Edecrin)
C. folic acid (Folvite)
D. thiamine (Vitamin B1)
Correct Answer: A. lactulose (Chronulac)
The client with cirrhosis has impaired ability to metabolize protein because of liver dysfunction. Administration of lactulose aids in the clearance of ammonia via the gastrointestinal (GI) tract. Lactulose reduces intestinal ammonia production and absorption in three ways. First, the colonic metabolism of sugars causes a laxative effect via an increase in intraluminal gas formation and osmolality which leads to a reduction in transit time and intraluminal pH. This laxative effect is also beneficial for constipation. Next, lactulose promotes increased uptake of ammonia by colonic bacteria which utilize the trapped colonic ammonia as a nitrogen source for protein synthesis. The reduction of intestinal pH facilitates this process, which favors the conversion of ammonia (NH3) produced by the gut bacteria, to ammonium (NH4+), an ionized form of the molecule, unable to cross biological membranes. Finally, lactulose also causes a reduction in intestinal production of ammonia. The acidic pH destroys urease-producing bacteria involved in the production of ammonia. The unabsorbed disaccharide also inhibits intestinal glutaminase activity, which blocks the intestinal uptake of glutamine, and its metabolism to ammonia.
Option B: Ethacrynic acid is a loop diuretic that gained FDA approval for widespread use in 1967. Unlike other loop diuretics, ethacrynic acid is a novel drug due to the absence of a sulfonamide group in its structure, allowing its use in critically ill patients with life-threatening sulfa-allergies. The main site of action is limited to the ascending limb of the nephron’s loop of Henle, which is responsible for sodium and chloride reabsorption. Ethacrynic acid has also demonstrated to cause venous dilation contributing to rapid pulmonary decongestion even before its onset of diuresis.
Option C: Folic acid and thiamine are vitamins, which may be used in clients with liver disease as supplemental therapy. Folic acid is the synthetic form of folate. Folate converts into tetrahydrofolic acid (THF), a compound that undergoes several transfer/methylation reactions that are important for the synthesis of nitrogenous bases in DNA and ribonucleic acid (RNA) and are necessary for the maturation of red blood cells (RBCs). There are small reserve pools in the liver and kidney. One of the most important indications for folate use is when considering the development of the central nervous system. Women planning on getting pregnant should take folic acid supplements to reduce the risk of neural tube defects (NTDs), such as spina bifida, arising in the developing fetus.
Option D: Vitamin B1 is one of the eight B vitamins. It has acquired several names since its discovery, including aneurin and, as of the year 2000, thiamin (thiamine). Because thiamin can only be stored in the body for a short time before excretion, a regular dietary intake of thiamin is necessary to maintain proper blood levels. Moderate amounts of thiamin are present in most foods, yet the food sources richest in thiamin include whole-grains, brown rice, pork, poultry, soybeans, nuts, dried beans, peas, and fortified or enriched grain products such as cereals. The recommended daily intake (RDI) for adults over age eighteen is 1.2 mg/day for men and 1.1 mg/day for women. For children, adequate intake levels are lower, with RDI levels at 0.2 mg/day during early infancy that steadily increase with age. Women of any age who are pregnant or should increase their daily intake of thiamin to 1.4 mg/day.