Xiangerkang Methyldopa Tablets

1. Indications and Usage
Hypertension:
Indicated for the treatment of mild to moderate hypertension, including hypertension associated with renal disease.
Pregnancy-Associated Hypertension:
Historically and currently considered a preferred agent for the management of hypertension during pregnancy.
2. Dosage and Administration
Adult Dosage:
Initial: 250 mg orally 2 to 3 times daily.
Titration: Dosage may be adjusted every 2 days to achieve the desired effect.
Maintenance: 500 mg to 2 g daily in 2 to 4 divided doses.
Maximum: Not to exceed 3 g daily.
Pediatric Dosage:
Initial: 10 mg/kg/day orally in 2 to 4 divided doses.
Maximum: 65 mg/kg/day or 3 g/day, whichever is less.
3. Mechanism of Action
Central Alpha-2 Agonist:
Methyldopa crosses the blood-brain barrier and is converted into alpha-methylnorepinephrine.
Physiological Effect:
Alpha-methylnorepinephrine stimulates central alpha-adrenergic inhibitory receptors, resulting in decreased sympathetic outflow from the CNS to the periphery, thereby reducing peripheral vascular resistance and blood pressure.
4. Safety and Warnings
Hepatic Dysfunction:
Liver disorders, including hepatitis and jaundice, may occur, particularly within the first 6 months of therapy. Monitor liver function tests periodically.
Positive Direct Coombs’ Test:
A positive direct Coombs’ test may develop in 10-20% of patients.
Hemolytic Anemia:
Rare cases of hemolytic anemia have been reported. If anemia occurs, perform a blood count and Coombs’ test.
Sedation and Dizziness:
Somnolence and dizziness are common, especially at the start of therapy.
5. Adverse Reactions
Most Common:
Somnolence, headache, fatigue, dizziness, sedation, dry mouth, nausea, vomiting, and peripheral edema.
Other:
Positive Coombs’ test, hemolytic anemia, hepatitis, depression, sexual dysfunction, and breast enlargement (gynecomastia).
6. Drug Interactions
Antihypertensives:
Additive hypotensive effects when used with other antihypertensive agents (e.g., thiazide diuretics).
Lithium:
Neurotoxicity may occur when combined with lithium.
Anticoagulants:
May potentiate the effects of oral anticoagulants.
7. Pharmaceutical Information
Chemical Composition:
Active Ingredient: Methyldopa.
Storage:
Store at controlled room temperature. Protect from light and moisture.