Methyldopa – a tablet for high blood pressure often used in pregnancy

Methyldopa – a tablet for high blood pressure often used in pregnancy

Methyldopa is a tablet for high blood pressure often used in pregnancy

What is Methyldopa?

Methyldopa is an antihypertensive (blood pressure lowering medication) that belongs to a class of drugs called centrally acting alpha-2 adrenoceptor agonists.

Unlike many other blood pressure medications that work on the heart or kidneys, methyldopa primarily works by affecting the central nervous system.

How it works

• Methyldopa stimulates specific receptors in the brain that signal the nervous system to relax.

• This reduces the signals sent to the heart and blood vessels, causing the blood vessels to widen (relax) and the heart rate to slow slightly.

• This results in a smoother flow of blood and a reduction in overall blood pressure.

Uses – What is Methyldopa used for?

Methyldopa is used to treat:

• High blood pressure (hypertension): It is rarely a first-choice treatment for the general population but is a “gold standard” for specific groups, e.g. in pregnancy.

• Hypertension in pregnancy: It is one of the most widely used and well-studied medicines for high blood pressure in pregnant women (including pre-eclampsia) because it has a long safety record for both mother and baby.

Dose

• Usually taken two to three times daily.

• Treatment typically starts at a low dose (e.g. 250 mg) to minimise initial drowsiness.

• The dose is gradually increased by a doctor until blood pressure is controlled.

• The typical maintenance dose ranges from 500 mg to 2,000 mg daily.

Side-effects

Common side-effects include:

• Drowsiness or tiredness (especially when starting treatment or increasing the dose).

• Dry mouth.

• Headache or dizziness.

• Nasal stuffiness.

Less common (but mores serious) side-effects:

• Depression or mood changes: Feeling low or unusually tearful.

• Liver problems: Jaundice (yellowing of the skin or eyes).

• Blood disorders: A rare type of anaemia (haemolytic anaemia).

• Fever: Unexplained fever shortly after starting the medication.

• Drug-induced lupus erythematosus (DILE): It can trigger autoimmune symptoms, including positive antinuclear antibodies (ANA), rarely, systemic lupus-like syndromes featuring pleuritis or fever. Symptoms usually resolve upon discontinuing the medication.

Monitoring

Doctors should monitor:

• Blood pressure: To ensure the medication is effective.

• Full Blood Count (FBC): To check for rare effects on red blood cells.

• Liver Function Tests (LFTs): To ensure the liver is processing the medication safely.

Tests done if required

• Coombs Test: A specific blood test to check for antibodies against red blood cells, if haemolytic anaemia is suspected.

• ANA, and dsDNA antibodies: May be required if drug induced SLE is suspected.

Note: Methyldopa can cause a “false positive” result on certain blood tests used for cross-matching blood for transfusions. Always inform medical staff you are taking this medication.