What common side effect is associated with Hydralazine and dihydropyridine calcium channel blockers?

Hydralazine and dihydropyridine calcium channel blockers are known to cause peripheral edema as a common side effect. This occurs primarily due to their effects on the vascular system. Hydralazine is a vasodilator that can lead to fluid retention as the body compensates for the drop in blood pressure by holding onto sodium and water, which can result in swelling, particularly in the lower extremities.

Dihydropyridine calcium channel blockers, like amlodipine and nifedipine, work by dilating blood vessels as well, leading to decreased systemic vascular resistance. The resultant drop in blood pressure can also trigger compensatory mechanisms that include increased capillary hydrostatic pressure, promoting fluid leakage into the interstitial space and contributing to peripheral edema.

While the other options—constipation, weight gain, and hepatotoxicity—are side effects associated with various medications, they are not commonly seen with hydralazine or dihydropyridine calcium channel blockers. Constipation is more typical with medications that affect motility, weight gain is generally not a prominent side effect of these agents, and hepatotoxicity is not a standard side effect of this class of medications, making peripheral edema the most appropriate answer in this context.