[Does the calcium antagonist verapamil modify calcium metabolism?]

Area of Science:

• Cardiovascular Pharmacology
• Endocrinology
• Clinical Chemistry

Context:

• Verapamil is a calcium channel blocker used for cardiovascular conditions.
• Calcium homeostasis is regulated by parathyroid hormone (PTH) and serum calcium levels.
• The impact of verapamil on calcium and PTH metabolism, especially during exercise, requires further elucidation.

Purpose:

• To investigate the effects of oral verapamil on serum/plasma calcium and parathyroid hormone levels at rest and during exercise in healthy individuals.
• To assess changes in ionized, pH-corrected ionized, and total calcium concentrations.
• To evaluate the relationship between calcium and PTH levels before and after verapamil administration.

Summary:

• Oral verapamil (4 x 80 mg/d) administration in 11 healthy volunteers led to increased total serum calcium (p<0.02) and decreased midregional parathyroid hormone (p<0.02) at rest.
• During bicycle exercise, verapamil administration resulted in a significant elevation of ionized (p<0.05) and pH-corrected ionized (p<0.05) plasma calcium.
• A slight increase in total serum calcium was also observed under exercise (p<0.1).

Impact:

• Verapamil influences calcium and parathyroid hormone metabolism, suggesting potential alterations in calcium homeostasis.
• The findings indicate that verapamil may affect the complex interplay between calcium levels and PTH secretion, particularly under physiological stress like exercise.
• This study provides insights into the metabolic effects of verapamil, relevant for its clinical application and understanding calcium regulation.