ATC code H05

ATC Code H05

The Anatomical Therapeutic Chemical (ATC) Classification System is a system used for the classification of drugs and other medical products. The ATC code H05 is designated for "Calcium homeostasis" agents, which are primarily involved in the regulation of calcium levels in the body. This category includes drugs that are used to treat conditions related to calcium metabolism, such as osteoporosis, hypercalcemia, and hypocalcemia.

Classification

The ATC code H05 is divided into several subcategories, each representing a different type of agent involved in calcium homeostasis:

• H05A - Parathyroid hormones and analogues: This group includes drugs that mimic the action of parathyroid hormone (PTH), which is crucial for maintaining calcium balance in the body. These agents are often used in the treatment of osteoporosis and other conditions where bone density is compromised.

• H05B - Anti-parathyroid agents: These drugs are used to counteract the effects of excessive parathyroid hormone, which can lead to conditions such as hypercalcemia. They are often used in the treatment of hyperparathyroidism.

Mechanism of Action

1. 1. 1. Parathyroid Hormones and Analogues (H05A)

Parathyroid hormones and their analogues work by stimulating osteoclasts, which are cells that break down bone tissue, releasing calcium into the bloodstream. This process helps to increase blood calcium levels. These agents also promote the reabsorption of calcium in the kidneys and increase the production of active vitamin D, which enhances calcium absorption from the gut.

1. 1. 1. Anti-parathyroid Agents (H05B)

Anti-parathyroid agents work by inhibiting the secretion or action of parathyroid hormone. This can help to reduce blood calcium levels in conditions where they are abnormally high, such as in primary or secondary hyperparathyroidism. Some of these agents may act directly on the parathyroid glands, while others may work by mimicking calcium, thereby reducing PTH secretion.

Clinical Uses

1. 1. 1. Osteoporosis

Drugs in the H05A category, such as teriparatide, are used in the treatment of osteoporosis, particularly in postmenopausal women and men at high risk of fractures. These agents help to increase bone mass and strength, reducing the risk of fractures.

1. 1. 1. Hyperparathyroidism

Anti-parathyroid agents are used to manage hyperparathyroidism, a condition characterized by excessive secretion of parathyroid hormone. This can occur in primary hyperparathyroidism, often due to a benign tumor of the parathyroid gland, or secondary hyperparathyroidism, which is commonly associated with chronic kidney disease.

Side Effects

1. 1. 1. Parathyroid Hormones and Analogues

Common side effects of parathyroid hormone analogues include nausea, joint pain, and dizziness. Long-term use may increase the risk of osteosarcoma, a rare bone cancer, which is why their use is typically limited to a maximum of two years.

1. 1. 1. Anti-parathyroid Agents

Side effects of anti-parathyroid agents can include hypocalcemia, which may cause symptoms such as muscle cramps, tingling, and seizures. Monitoring of calcium levels is essential during treatment.

Also see

• Osteoporosis
• Hyperparathyroidism
• Calcium metabolism
• Vitamin D