Dihydropyridines · What Are They, Mechanism of Action, Indications, Side Effects, and More

Dihydropyridines are a type of calcium channel blocker (CCB), which refer to a group of medications that block calcium channels located in the muscle cells of the heart and arterial blood vessels, thereby reducing the entry of calcium ions into the cell. By blocking these channels, CCBs promote blood vessel dilation (i.e., vasodilation), as well as changes in heart function, including reductions in heart rate, strength of contractility, and speed of conduction within the heart.  

Overall, these effects contribute to a drop in blood pressure and a decrease in the oxygen requirements of the heart. Because of these cardiovascular effects, CCBs can be used to treat hypertension (i.e., high blood pressure), among other heart problems, including angina and cardiac arrhythmias (i.e., disturbances in the heart rhythm).  

According to their main site of action, CCBs can be categorized into two main classes: dihydropyridines and non-dihydropyridines, each with different uses and side effects.  

Dihydropyridines act predominantly on blood vessels to promote vasodilation without having much of a direct effect on cardiac function. They include medications that end with the suffix “-dipine”, such as nifedipine, nicardipine, nimodipine, and amlodipine, to name a few.   

On the other hand, non-dihydropyridines have a greater effect on the heart but are less effective in promoting vasodilation. Non-dihydropyridines include fewer medications, such as verapamil and diltiazem.  

Dihydropyridines can be used for a variety of conditions that relate to increased vascular resistance, or increased contraction of blood vessels. Most commonly, they are used to treat hypertension by way of vasodilation. Additionally, some dihydropyridines, like nifedipine, can be given to treat high blood pressure in pregnant individuals.  

In addition, long-acting dihydropyridines can be used to treat vasospastic or Prinzmetal angina, which is caused by the narrowing of the blood vessels that supply blood to the heart (i.e., coronary arteries). In such cases, dihydropyridines can dilate the coronary arteries, increasing blood flow to the heart muscle. Moreover, they can also be used to prevent stable angina, a sudden chest pain that results from a compromised oxygen supply to the heart.  

Dihydropyridines can also be used to treat Raynaud syndrome, a medical condition caused by the narrowing of the small arteries of the fingertips when exposed to cold temperatures or stress. Furthermore, some dihydropyridines, such as nifedipine, can also be used to slow down uterine contractions in pregnant individuals at risk of preterm birth, thereby reducing the risk of neonatal complications. Lastly, nimodipine can be used to prevent cerebral vasospasm (i.e. a sudden narrowing of the cerebral blood vessels), a serious complication that can arise after the development of a subarachnoid brain hemorrhage, or the bleeding within the protective membranes that surround the brain and spinal cord.