Is it Safe to Use Methyldopa in Pregnancy?

Methyldopa tablets, the indication is hypertension.

Drug Name: Methyldopa tablets

Drug type: Prescription drugs, medicines for medical workers' injuries
Use classification: Sympathetic inhibitor

Methyldopa tablets

Methyldopa

Methyl dopa sheet traits

This product is a sugar-coated tablet, which appears white after removing the sugar coating.

Methyldopa tablets indications

hypertension.

Methyl dopa tablets specifications

0.25g

Methyldopa tablets usage dosage

1. Common adult dose:
Orally, 250mg / time, divided into 2 to 3 times / day. Adjust the dose every 2 days to achieve the desired effect. Generally increase the amount at night to reduce the excessive sedation of the drug. If combined with thiazide diuretics needs to be reduced, the initial dose is controlled at 500mg / day, but the diuretic dose can be unchanged. Maintain the amount of 0.5 to 2 g / day, divided into 2 to 4 times orally, the maximum dose should not exceed 3 g / day. Due to the short duration of action of methyldopa, other antihypertensive treatments should be given within 48 hours after discontinuation. Drug resistance can develop after 2 to 3 months of administration, and diuretics can restore curative effects.
2. Commonly used amount for children:
Orally, 10 mg / kg daily, or 300 mg / m ^{2 of} body surface area, divided into 2 to 4 times. Adjust the dose every 2 days to achieve the required effect. The maximum dose does not exceed 65 mg / kg or 3 g / day.

Adverse effects of methyldopa tablets

1. Sedation, headaches, and fatigue appear more often than at the beginning of medication and doses, and are usually transient.
2. More common are: lower limb swelling caused by water and sodium retention, dry mouth.
3 Rarely: drug fever or eosinophilia, liver function changes (may be immune or allergic), mental changes (depression or anxiety, nightmares, insomnia), decreased sexual function, diarrhea, enlarged breasts, Nausea, vomiting, and fainting.
4 Occasionally aggravated angina pectoris and heart failure.
5. Rare: prolonged carotid sinus sensitivity and orthostatic hypotension time, weight gain, sinus bradycardia, liver damage, pancreatitis, colitis, salivary adenitis, tongue pain or black tongue, constipation, abdominal distension, gassing , Hyperprolactinemia, bone marrow suppression, thrombocytopenia, hemolytic anemia, leukopenia, positive antinuclear antibodies, LE cells, rheumatoid factor, positive direct antiglobulin (Coombs) test, myocarditis, pericarditis, vasculitis, Lupus-like syndrome, Parkinson's disease, tremor paralysis, slow response, unconscious chorea, cerebrovascular insufficiency symptoms, mental disorders such as dreaming, sedation, weakness, paresthesia, elevated urea nitrogen (BUN), joint pain May be accompanied by joint swelling, muscle pain, nasal congestion, epidermal necrosis, rash, amenorrhea, male mammary gland development, and lactation.
6. Rare are: granulocytopenia, which returns to normal after withdrawal; fatal hepatocyte necrosis.

Methyldopa tablets contraindications

1. Active liver disease, such as acute hepatitis active liver cirrhosis.
2. The direct antiglobulin (Coombs) test was positive.

Methyldopa tablets precautions

1. Positive direct antiglobulin (Coombs) test, hemolytic anemia, and abnormal liver function may be closely related to taking methyldopa and occasionally cause death. Therefore, the blood routine, Coombs test and liver function should be checked regularly before and during the medication. If hemolytic anemia occurs, the drug should be discontinued immediately. Anemia usually improves quickly, otherwise it should be treated with corticosteroids. This type of patient cannot use methyldopa again. A positive direct antiglobulin (Coombs) test can return to normal after weeks or months of methyldopa withdrawal.
2. If both direct and indirect anti-globulin (Coombs) tests are positive, there will be problems with cross-matching in the primary side, and you should consult a hematology or blood transfusion specialist to resolve it.
3 Because methyldopa is mainly eliminated by the kidney, those with renal insufficiency should be used with caution.
4 Liver function must be checked regularly, especially within the first 2 to 3 months of medication. If the problem is found, the body temperature and liver function can be recovered in those who immediately stop taking the drug. This type of patient cannot use methyldopa again. Methyldopa is used with caution in patients with liver disease and liver dysfunction.
5. Patients who develop edema or gain weight with methyldopa can be treated with diuretics. This product should be discontinued once the edema progresses or there are signs of heart failure.
6. During the dialysis process, methyldopa is excreted, and blood pressure will occasionally rise.
7. Patients with severe bilateral cerebrovascular disease should stop taking the medicine immediately if involuntary chorea occurs during the medication.
8. Methyldopa can affect the test values of the following laboratories: uric acid by the tungstate phosphate method; creatinine by the picrate method; SGOT by the colorimetric method.
9. Methyldopa can falsely increase catecholamines in urine samples by fluorescence method and interfere with the diagnosis of pheochromocytoma.
10 Use with caution in patients with pheochromocytoma.

Methyldopa tablets for pregnant and lactating women

This product can pass through the placenta. Research in the human body is inadequate. Existing studies have shown that pregnant women have no significant harmful effects on the fetus after taking the drug, so methyldopa can be used in pregnant women if necessary. Methyldopa can be excreted into milk, but no effects on infants have been reported. Despite this, breastfeeding women should be used with caution.

Methyldopa tablets for children

Lack of research on pediatric safety

Methyldopa tablets for elderly

The elderly are sensitive to antihypertensive effects and have poor renal function.

Methyldopa tablets drug interactions

1. This product can increase the effect of oral anticoagulants.
2. This product can strengthen the role of central nervous system inhibitors.
3 Tricyclic antidepressants, sympathomimetics and non-steroidal anti-inflammatory analgesics can reduce the hypotensive effect of this product.
4 This product can increase blood prolactin concentration and interfere with the action of bromocriptine.
5. Synergistic effect with other antihypertensive drugs.
6. Combined with levodopa can strengthen central nervous system toxicity.
7. In combination with anesthetics, the dose of anesthetics must be reduced.
8. When used in combination with lithium agents, the toxic effects of lithium agents must be guarded against.

Methyldopa tablets overdose

Methyldopa can be eliminated by dialysis. Drug overdose will produce various reactions of acute hypotension with brain and gastrointestinal dysfunction, such as excessive sedation, weakness, bradycardia, dizziness, unresponsiveness, constipation, bloating, exhaust, diarrhea, nausea, vomiting, etc. Treatment should be symptomatic.

Methyldopa tablets pharmacology and toxicology

Pharmacology:
1. Methyldopa is an aromatic amino acid decarboxylase inhibitor.
2. Only the L-isomer of methyldopa has antihypertensive activity in humans, and the racemic body (DL--methyldopa) requires 2 times the dose to achieve the same hypotensive effect. Its antihypertensive effect may be through its active metabolite methyl norepinephrine to stimulate the central inhibitory -adrenergic receptor and as a pseudo-neurotransmitter, reducing plasma renin activity, thereby lowering arterial blood pressure.
3 Methyldopa can reduce serotonin, dopamine, norepinephrine, and methyl adrenaline concentrations in tissues.
4 Methyldopa has no direct effect on cardiac function and usually does not reduce glomerular filtration rate, renal blood flow, and filtration fraction.
5. Cardiac output remains constant at normal heart rate, and some patients experience slower heart rates.
6. Plasma renin activity decreases during treatment.
7. Methyldopa lowers supine and orthostatic blood pressure, and orthostatic hypotension rarely occurs. Rarely hypotension during daytime exercise.
Toxicology:
Carcinogenic, mutagenic, reproductive toxicity Mice and rats take 1800 mg / kg and 240 mg / kg of methyldopa daily (equivalent to 30 times and 4 times the maximum human dose, respectively), and have no carcinogenic effect for 2 years. Ames test methyldopa did not increase chromosome aberration and sister chromatid exchange in ovarian germ cells of Chinese hamsters. Male and female rats were given methyldopa 100 mg / kg daily, and no fertility was affected. Methyldopa reduces sperm count, sperm motility, and late sperm count. Male rats were given 200 mg / kg and 400 mg / kg of methyldopa daily (based on body surface area, approximately 0.5 times and 1 times the maximum daily human dose), and the male fertility index decreased. Mice were administered orally with methyldopa 1000 mg / kg, rabbits 200 mg / kg, and rats 100 mg / kg (based on body surface area, equivalent to 1.4 times, 1.1 times, and 0.2 times the human daily dose, respectively), which were not harmful to the fetus. influences.

Methyldopa tablets pharmacokinetics

Methyldopa varies by mouth, about 50%, and binds to less than 20% of plasma proteins. The hypotensive effect reaches a peak 4 to 6 hours after a single oral administration, and the effect lasts 12 to 24 hours. The peak of the effect is reached 2 to 3 days after repeated oral administration, and lasts to 24 to 48 hours after stopping the drug; once the effective antihypertensive dose is reached, most people can produce a stable antihypertensive effect within 12 to 24 hours. Blood pressure recovered 24 to 48 hours after discontinuation. Plasma half-life is about 1.7 hours, and 3.6 hours without urine. The drug is mainly metabolized in the liver, producing various metabolites such as methyl norepinephrine, and nearly 70% is excreted in the form of the original form and a small amount of metabolites through the urine. The renal clearance rate of normal people is about 130ml / min, and the renal function declines. The body was completely cleared 36 hours after oral administration.