DOMEPA Methyldopa 250mg Film-Coated Tablet 100's
Indications/Uses
Dosage/Direction for Use
Maintenance therapy: The usually daily dosage is 0.5-2 g per day in 2-4 divided doses. The maximum recommended daily dosage is 3 g.
Concomitant usage of thiazide is recommended if the therapy has not been started with a thiazide or if effective control of blood pressure cannot be maintained with the daily dosage of 2 g of methyldopa.
Lower dose of methyldopa may be used in elderly or patients with kidney impaired renal function.
Use in the elderly: The starting dosage is 125 mg, 2 times per day; then increase slowly but not to exceed the maximum dosage of 2 g per day.
Use in the children: Initial daily dosage is 10 mg/kg of body weight, in 2-4 divided doses. The maximum dosage is 650 mg/kg or 3 g daily.
Overdosage
In the event of overdose, treatment is usually symptomatic and supportive. When ingestion is recent, gastric lavage or emesis may reduce absorption. When ingestion has been earlier, infusions may be helpful to promote urinary excretion. Otherwise, management includes special attention to cardiac rate and output, blood volume, electrolyte imbalance, paralytic ileus and cerebral activity.
Sympathomimetic drugs (e.g.: levarterenol, epinephrine, metaraminol bitartrate) may indicated.
Methyldopa is dialyzable.
Administration
Contraindications
Warnings
Special Precautions
Use In Pregnancy & Lactation
Adverse Reactions
Blood and lymphatic system disorders: hemolytic anemia, bone-marrow failure, leukopenia, granulocytopenia, thrombocytopenia, eosinophilia.
Endocrine disorders: hyperprolactinemia.
Psychiatric disorders: psychic disturbances including nightmares, reversible mild psychoses or depression, decreased libido.
Nervous system disorders: Sedation (usually transient), headache, paraesthesia, parkinsonism, VIIth nerve paralysis, choreoathetosis, mental impairment, carotid sinus syndrome, dizziness, symptoms of cerebrovascular insufficiency (may be due to lowering of blood pressure).
Cardiac disorders: bradycardia, angina pectoris, myocarditis, pericarditis, atrioventricular block.
Vascular disorders: orthostatic hypotension (decrease daily dosage).
Respiratory, thoracic and mediastinal disorders: Nasal congestion.
Gastrointestinal disorders: Nausea, vomiting, abdominal distension, constipation, flatulence, diarrhoea, colitis, dry mouth, glossodynia, tongue discolouration, pancreatitis.
Hepatobiliary disorders: Liver disorders including hepatitis, jaundice.
Skin and subcutaneous tissue disorders: Rash (eczema, lichenoid eruption), toxic epidermal necrolysis.
Musculoskeletal and connective tissue disorders: Lupus-like syndrome, mild arthralgia with or without joint swelling myalgia.
Reproductive system and breast disorders: breast enlargement, gynaecomastia, amenorrhea, lactation disorder, erectile dysfunction, ejaculation failure.
General disorder and administration site condition: Asthenia, oedema (and weight gain) usually relieved by use of a diuretic (discontinue methyldopa if oedema progresses or signs of heart failure appear), pyrexia.
Investigations: Positive Coombs test, positive tests for antinuclear antibody, LE cells and rheumatoid factor, abnormal liver-function tests, increased blood urea.
Inform the doctor any adverse effects occurring during therapy.
Drug Interactions
Anesthetics: dose reduction of anesthetics may be required. If hypotension occurs during anesthesia, it usually can be controlled by vasopressors.
Lithium: because of increasing of lithium toxicity.
Monoamine oxidase (MAO) inhibitors: because of causing excessive hypotension.
Amphetamines, other central nervous system (CNS) stimulants, tricyclic antidepressants: because antihypertensive effect may be antagonized and control of blood pressure may be lost.
Iron hematinic: because of decreasing plasma concentration and antihypertensive effect of methyldopa.
Oral contraceptive: because of increasing risk of vascular damage and difficulty in controlling blood pressure.
Storage
Action
Reduction in plasma renin activity may also contribute to the antihypertensive effect of methyldopa. Methyldopa inhibits decarboxylation of dihydroxyphenylalanine (dopa) (precursor of norepinephrine) and of 5-hydroxytryptophan (precursor of serotonin) in the central nervous system and in most peripheral tissues. Although the major hypotensive effect is not attributed to decarboxylase inhibition, some contribution by peripheral mechanism cannot be ruled out. Methyldopa has been proven to decrease tissue concentrations of serotonin, dopamine, norepinephrine and epinephrine.
Methyldopa lowers the blood pressure both in standing and when lying down. Methyldopa has no direct effect on kidney and heart function. Heart minute volume is usually maintained, without any increase of pulse beat-frequency. In some cases one may see that the pulse heart rate decreases. Glomerular filtration, kidney blood flow or filtration fraction is usually not affected. This means that effective blood pressure control can be maintained also in patients with decreased kidney function. Symptoms of postural hypotension, hypotension during and variation in blood pressure during the period are very rarely seen problems.
Methyldopa can be used in combination with other blood pressure lowering drugs, especially with thiazide diuretics and including combination of thiazide plus amiloride. Methyldopa can also be combined with beta receptor blocking drugs.
Pharmacokinetics: Since the key to the effect of methyldopa is through its metabolism to alpha-methyl-norepinephrine, the plasma concentration of methyldopa itself has limited relevance predicted effect.
The absorption of methyldopa is incomplete. Average bioavailability only reaches 25% of given dose and the variation between individuals is very large. Maximum plasma concentration is reached within 2-4 hours after an oral dose. The antihypertensive effect is maximal in 4-6 hours after a single oral dose. Plasma half-life is 1-2 hours in patients with normal kidney function and increases when kidney function decreases. Volume of distribution is 0.6 liter/kg.
Approximately 70% of given dose is excreted in the urine, where of 60% as free methyldopa and the rest as conjugated metabolites.
MedsGo Class
Features
- Methyldopa