Detailed Explanation of Drug Treatment Regimens for Obesity-Related Osteoarthritis

Drug Treatment

Drug treatment for osteoarthritis should be limited to the painful phase. Both non-steroidal anti-inflammatory drugs (NSAIDs) and analgesics are effective. These drugs have similar effects on pain and function in knee osteoarthritis. NSAIDs are generally believed to reduce the inflammatory components in the affected joint. NSAIDs should be limited to the symptomatic phase when analgesics are insufficient to relieve pain.

1. Analgesics
Clinically, drug treatment usually begins with a simple analgesic (such as acetaminophen) to avoid damage to the gastric mucosa. Special attention should be paid to dosage adjustments in elderly patients. Patients with alcohol poisoning or glutathione depletion disorders are prone to liver damage when using acetaminophen and should use it with caution. If pain cannot be relieved by acetaminophen alone, combination therapy with codeine or dextropropoxyphene can be considered; however, combination therapy often increases adverse reactions such as constipation, dizziness, and drowsiness. 1. Prophylactic use of analgesics can be used when patients prepare for activities that cause pain, such as walking or exercise. Prophylactic use of analgesics can also be considered when pain does not occur.

2. Nonsteroidal Anti-inflammatory Drugs (NSAIDs)
The excretion kinetics of NSAIDs are age-related. Elderly patients are prone to adverse reactions such as indigestion, upper gastrointestinal erosion, ulceration and bleeding, renal dysfunction, increased blood pressure, and fluid retention. Therefore, patients with osteoarthritis who must use NSAIDs should be aware of their adverse reactions. Furthermore, NSAIDs may interact with anticoagulants, oral antihyperglycemic agents, anticonvulsants, antihypertensive drugs, diuretics, and corticosteroids, leading to adverse reactions.

Elderly patients, especially those with a history of kidney damage, are at high risk of developing renal adverse reactions when using NSAIDs. NSAIDs affect the synthesis of renal prostaglandins, causing water and electrolyte retention, and in rare cases, acute renal failure. In the vast majority of NSAID-induced kidney damage, elevated serum creatinine (within the first few days of treatment), elevated serum potassium, weight gain, and decreased urine output are observed. Furthermore, NSAIDs have some hepatotoxicity and also have effects on the cardiovascular and central nervous systems.

For patients with a history of peptic ulcer disease or concurrent use of corticosteroids, prophylactic use of anti-ulcer drugs, such as prostaglandin E or misoprostol, should be considered. If anti-ulcer treatment is not tolerated, barrier complexes such as sucralfate, secretion inhibitors such as omeprazole, and histamine H₂ receptor blockers such as ranitidine or cimetidine can be chosen.

For patients with pain and mild osteoarthritis, topical medication can be considered. Topical formulations allow the active ingredient to reach therapeutic levels locally while maintaining a low concentration in the serum, minimizing systemic adverse reactions.

3. Intra-articular Corticosteroids
Intra-articular corticosteroids are commonly used to treat osteoarthritis. They are mostly used for patients experiencing pain and joint effusion during the inflammatory phase. Corticosteroids only provide short-term pain relief, and long-term use is not ideal. The long-term effects of repeated intra-articular corticosteroid injections on cartilage are currently unclear. Intra-articular corticosteroids are generally only used when other treatments are ineffective.

4. Intra-articular Hyaluronic Acid
Hyaluronic acid is a normal component of synovial fluid. In addition to its joint lubrication function, it also maintains the nutritional status of cartilage. The indication for intra-articular injection of hyaluronic acid is knee pain with radiographic abnormalities.

5. Extra-articular Corticosteroids
Peri-hip injection of corticosteroids can relieve pain and improve function in some patients and can be considered for patients with mild to moderate knee osteoarthritis.

6. Topical Capsaicin
Endogenous neuropeptides are not only involved in the pathogenesis and regulation of neuropathic pain, but also in arthritis pain. Substance P is elevated in the plasma and synovial tissue of patients with rheumatoid arthritis and osteoarthritis.

Topical application of 0.025% capsaicin cream has a significant analgesic effect in the treatment of osteoarthritis.