Mr. Jones suffers from constipation. He goes to the drug store to buy a laxative. Mr. Jones should avoid which medication?

Mr. Jones suffers from constipation. He goes to the drug store to buy a laxative. Mr. Jones should avoid which medication?

• A. Senna
• B. Milk of Magnesia
• C. Bisacodyl
• D. Docusate

Answer: (B)

When choosing a laxative, consider how the drug works and any patient-specific risks, especially kidney function. Milk of Magnesia is a magnesium-containing osmotic laxative. It works by drawing water into the intestine to soften stool and stimulate evacuation, but excess magnesium can build up in the body if the kidneys can’t clear it. This can lead to hypermagnesemia, with symptoms like weakness, confusion, low blood pressure, and, in severe cases, heart rhythm problems. Because of this risk, it’s best avoided in patients with renal impairment or those at risk of electrolyte disturbances. The other options work by different mechanisms and are generally safer in someone without kidney problems: stimulant laxatives (which increase bowel contractions) and a stool softener (which makes stool easier to pass). But in a patient where kidney function is a concern, avoiding the magnesium-containing option is the prudent choice.

When choosing a laxative, consider how the drug works and any patient-specific risks, especially kidney function. Milk of Magnesia is a magnesium-containing osmotic laxative. It works by drawing water into the intestine to soften stool and stimulate evacuation, but excess magnesium can build up in the body if the kidneys can’t clear it. This can lead to hypermagnesemia, with symptoms like weakness, confusion, low blood pressure, and, in severe cases, heart rhythm problems. Because of this risk, it’s best avoided in patients with renal impairment or those at risk of electrolyte disturbances.

The other options work by different mechanisms and are generally safer in someone without kidney problems: stimulant laxatives (which increase bowel contractions) and a stool softener (which makes stool easier to pass). But in a patient where kidney function is a concern, avoiding the magnesium-containing option is the prudent choice.