Gastrointestinal, Antiemetic, and Anemia Medications

Managing Diarrhea

Antidiarrheal agents, such as loperamide, are used to slow intestinal motility. However, they should not be used if an infectious cause of diarrhea (such as certain bacterial infections) is suspected, as slowing motility can trap toxins in the body.

Managing Constipation

Laxatives are classified by their physiological mechanism:

1. Emollients (Stool Softeners): Docusate is used to soften the stool, making it easier to pass. This is often the safest option for long-term use.
2. Hyperosmotics: Lactulose draws water into the colon to increase motility. It has a specific clinical use in treating hepatic encephalopathy.
3. Saline Laxatives: These include magnesium salts. Caution: These are contraindicated in patients with renal failure because the body may struggle to excrete the magnesium.
4. Stimulants: Bisacodyl directly stimulates the intestinal muscles. While effective for quick relief, they carry a high risk of laxative dependence, where the bowel becomes unable to function normally without chemical stimulation.

Antiemetic Medications

Nausea and vomiting can be managed through several different pathways in the central and peripheral nervous systems.

• Anticholinergics (e.g., Scopolamine): Often used as a topical patch for motion sickness. They are contraindicated in patients with glaucoma or those with known allergies to atropine.
• Antidopaminergics (e.g., Promethazine): These are used for both nausea and sedation. A critical nursing assessment is monitoring for extrapyramidal symptoms (EPS) and tardive dyskinesias (involuntary, repetitive movements).
• Prokinetics (e.g., Metoclopramide): These increase GI motility to help empty the stomach. Due to the risk of movement disorders, the FDA has issued warnings regarding their long-term use.
• Serotonin Blockers (e.g., Ondansetron): Frequently used for chemotherapy-induced nausea.

Safety Alert: Ondansetron carries a box warning for QT prolongation (a heart rhythm issue) and potential congenital defects if used during pregnancy.

Potassium and Anemia Medications

Potassium Administration

Potassium is an essential electrolyte for cardiac function. Because it is so critical to heart rhythm, administration must be extremely controlled.

• Oral Potassium: Can cause significant GI irritation.
• IV Potassium: This is a high-alert medication. It must never be given undiluted. When administered via a peripheral line, the rate should generally not exceed $10\text{ mEq/hr}$. Continuous cardiac monitoring is required during administration.

Iron Supplements

Iron is used to treat anemia, but its administration requires specific techniques to ensure efficacy and safety.

• Ferrous Sulfate: To improve absorption, it should be taken with Vitamin C (such as orange juice). If the patient experiences GI upset, it can be taken with food, though this may slightly decrease absorption. Note that liquid iron can stain teeth.
• Iron Dextran: This is used for more severe cases. Because of the risk of anaphylaxis, a test dose is required before full administration. When given via intramuscular (IM) injection, the Z-track method must be used to prevent skin staining and irritation.