How does chronic kidney disease (CKD) primarily affect medication effects in patients?

Chronic kidney disease (CKD) has a significant impact on pharmacokinetics, particularly with respect to how medications are metabolized and eliminated from the body. In CKD, the kidney's ability to filter and eliminate waste products, including medications, is diminished. This leads to the accumulation of drugs in the body, which can cause elevated serum drug levels.

As kidney function declines, the risk of toxicity also increases because many drugs are either excreted by the kidneys or require adjustment in dosage to prevent accumulation and adverse effects. For example, medications that are normally cleared efficiently may become problematic in patients with CKD, leading to potentially harmful side effects or toxic reactions. This underscores the need for careful monitoring and adjustment of medication dosages in patients with chronic kidney disease to mitigate these risks.

The other options do not accurately capture the primary concern in CKD regarding medication effects. While drug elimination may be slowed, the central issue is the increase in serum drug levels and the associated risk of toxicity, making the chosen answer the most accurate reflection of how CKD affects medication effects.