Dopatab M250 Methyldopa Tablet

DOPATAB M250 TABLET

 

DESCRIPTION

Round, pale yellow film-coaled tablet, bevel-edged, shallow convex faces.

 

COMPOSITION

Methyldopa equivalent to anhydrous Methyldopa 250 mg per tablet.

 

ACTIONS AND PHARMACOLOGY

The exact mechanism of antihypertensive action is unknown. It is thought to involve stimulation of central alpha-adrenergic receptors by a metabolite, alpha-methylnorepinephrine, thus inhibiting sympathetic outflow to the heart, kidneys and peripheral vasculature. Reduced peripheral resistance and plasma renin activity levels may also contribute to its effect.

 

PHARMACOKINETICS

Absorption
Absorption of methyldopa from the gastrointestinal tract is variable but averages approximately 50%.

Protein Binding
Methyldopa – Low (less than 20%);
Sulphate conjugate – Moderate

Biotransformation
It is extensively metabolised and is converted to alpha-methylnorepinephrine in central adrenergic neurons; methyldopate hydrochloride is hydrolysed to methyldopa.
Sulphate conjugation occurs to a greater extent after oral than after intravenous administration.

Half-life
Normal – Alpha: 1.7 hours;
Anuric – Alpha: 3.6 hours

Time to peak effect
Single dose – 4 to 6 hours;
Multiple doses – 2 to 3 days

Duration of action
Single dose – 12 to 24 hours;
Multiple doses – 24 to 48 hours

Excretion
Renal; approximately 70% of absorbed drug is excreted in urine as methyldopa and its mono-O-sulfate metabolite.
Unabsorbed oral methyldopa is excreted unchanged in the feaces.

 

INDICATION

For treatment of moderate to severe hypertension.

 

CONTRAINDICATION

Not recommended for patients with acute liver disease or phaeochromocytoma.

 

PRECAUTIONS

• Evidence of hemolytic anaemia is an indication for discontinuing the drug.

• Positive Coombs’ tests may indicate an incompatible cross-match when transfusion is required and an indirect Combs’ test should be carried out.

• Safety for use in pregnancy and lactation has not been established.

• Caution if any kind of surgery or dialysis is required.

 

PREGNANCY AND LACTATION

Safety for use in pregnancy and lactation has not been established.

 

MAIN SIDE/ADVERSE EFFECTS

Drowsiness, edema, dry mouth and headache.

 

DRUG INTERACTIONS

• Concurrent use with the following drugs is not recommended: Monoamine oxidase (MAO) inhibitors, levodopa and methotrimeprazine.

• Concurrent use with the following drugs requires careful monitoring: Alcohol, antihypertensives, general anaesthetics and norepinephrine.

 

OVERDOSAGE

Clinical features: Dizziness, drowsiness, hypotension, tachycardia or bradycardia, hypothermia, extra-pyramidal signs, coma.

Treat overdosage by emesis or gastric lavage, if appropriate; and IV 1-2 mg benztropine if extrapyramidal signs are present.

 

DOSAGE AND ADMINISTRATION

Adults

Initial-Oral, 250 mg two or three times a day for two days, the dosage then being adjusted as directed.

Maintenance – Oral, 500 mg to 2 g a day, divided into two to four doses, not exceeding 3 g daily.

Children
Oral, initially 10 mg per kg of body weight daily, divided into two to four doses, the dosage then being adjusted as directed, not exceeding 65 mg per kg of body weight or 3 g daily, whichever is less.

 

Storage

Store below 25°C. Protect from light.

 

Presentation/Packing

Blister of 10 x 10’s

 

Manufactured by

HOVID Bhd.

121, Jalan Tunku Abdul Rahman, 30010 lpoh, Malaysia.

 

Revision date: September 2013

Leave a Reply