11.7: Antianginal Drugs: Calcium Channel Blockers and Ranolazine

Angina pectoris, a primary symptom of ischemic heart disease, requires careful pharmacological interventions. In this context, calcium channel blockers (CCBs) and ranolazine have emerged as crucial pharmacotherapeutic agents, providing deep insights into the complexities of angina management.

CCBs, a diverse class that includes dihydropyridines (nifedipine) and diphenylalkylamines (verapamil and diltiazem), exert their effect by blocking calcium channels in cardiac and smooth muscle cells. This blockade reduces the influx of calcium ions, leading to vasodilation and a decrease in myocardial oxygen demand. These agents, which are administered orally, undergo extensive metabolism. Certain compounds, such as verapamil and diltiazem, can also be administered intravenously. However, using CCBs may result in side effects, including headaches, dizziness, and peripheral edema.

In contrast, ranolazine, a sodium-channel blocker, operates through a more nuanced mechanism. It inhibits the late-phase sodium current in cardiac cells during repolarization, thereby preventing calcium entry via the sodium-calcium exchanger. This intricate regulation reduces intracellular sodium and calcium levels, promoting relaxation within the cardiac muscle and increasing coronary blood flow. Following oral administration, ranolazine undergoes substantial metabolism, primarily mediated by CYP3A enzymes. However, its therapeutic use is associated with side effects such as dizziness, headaches, constipation, and nausea.

The interplay between CCBs and ranolazine in treating angina pectoris highlights the delicate balance between precision and complexity. The careful regulation of calcium dynamics and sodium currents outlines a path toward relief, although it is challenging.

Calcium channel blockers, or CCBs, and ranolazine are two important types of drugs used to treat angina pectoris.

CCBs block calcium channels in cardiac and smooth muscle cells and inhibit the influx of calcium ions, leading to vasodilation and reduced myocardial oxygen demand.

CCBs comprise dihydropyridines, such as nifedipine, phenylalkylamines, such as verapamil, and benzothiazepines such as diltiazem.

All CCBs that are administered orally undergo extensive metabolism. Drugs like verapamil and diltiazem can also be given via intravenous routes.

Side effects of CCBs include headache, dizziness, and peripheral edema.

Sodium-channel blockers like ranolazine inhibit the late-phase sodium current in cardiac cells during repolarization, which prevents calcium entry via the sodium-calcium exchanger. As a result, intracellular levels of sodium and calcium decrease, relaxing the cardiac muscle and improving coronary blood flow.

Ranolazine is well absorbed when taken orally and is primarily metabolized by CYP3A enzymes.

Common side effects of ranolazine include dizziness, headache, constipation, and nausea.