Quiz 33: Pharmacotherapy of Fluid Imbalance, Electrolyte, and Acidbase Disorders


Furosemide (Lasix) is a loop diuretic. These are the diuretics that act on the ascending loop of Henle of a nephron. The indications of loop diuretics are hypertension, edema, and congestive heart failure. Lasix results in elimination of excess fluid and electrolytes from the body. The major electrolytes such as sodium, potassium, and chlorine are eliminated in the process. The possible adverse drug reactions are hyponatremia (decreased serum sodium level) and hypokalemia (decreased serum potassium level). When a patient is getting discharged with a loop diuretic in the discharge advice, it is always recommended to add potassium supplement to avoid or to reduce the risk of hypokalemia.

After the administration of the drug orally, the drug moves from the gastrointestinal tract (GI) tract to the extracellular fluid compartment (plasma) to enter the systemic circulation. For the drug to get absorbed into the blood from the GI tract it has to overcome few physico-chemical barriers. Factors that affect the absorption of the drug are as follows: • Drug solubility and dissolution rate • Particle size • Amorphism (drugs existing in only one form) and polymorphism (drugs existing in more than one form) • Lipophilicity of the drug • Salt form of drug • Drug stability Barriers that the drugs have to overcome to pass into plasma are: • For a drug to get absorbed it should first be converted to the aqueous solution. The drug that is highly soluble is well absorbed • Decreased particle size increases solubility of drug and rate of absorption. • Some part of the drug that are bound to intestinal contents cannot pass through the intestinal membrane • Only the unionized drugs having sufficient lipid solubility are absorbed into blood • Hence the drug must have sufficient aqueous solubility to be dissolved and good lipid solubility to cross the bi-lipid layer of the GI tract.

Ms. Peggy has been admitted in the hospital to undergo removal of gall stones, she has been ordered a laparoscopic surgery. The nurse starts her with IV solution of D 5 W at the rate of 15ml/h. The nurse must justify that the need for administering fluids intravenously is to maintain the loss of fluid during the surgical procedures. Though the mode of surgery is laparoscopic, incisions are made, which leads to loss of blood. Therefore, it is important to maintain the fluid electrolyte balance and so there is need for administrating fluids before surgery.

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