Hy-Po-Tone 250 mg, 500 mg Film-coated tablet

HY-PO-TONE is indicated in the treatment of essential hypertension.

Doses of 250 mg two or three times daily during the first 48 hours. Thereafter, the daily dosage may be adjusted preferably at intervals of not less than 48 hours intervals until an adequate response has been achieved. The usual dose is from 500 mg to 2 g daily. A suggested initial dose for children is 10 mg/kg body mass daily in divided doses.

HY-PO-TONE is contraindicated in:

• Persons known to be hypersensitive to methyldopa or its excipients.
• Impaired kidney or liver function or with a history of liver disease.
• Mental depression.
• It should not be given to patients with acute liver disease.
• Phaeochromocytoma.
• Porphyria.
• Patients on therapy with monoamine oxidase inhibitors (MAOI).

It is advisable to do periodic blood counts and to perform liver function tests at intervals during the first 6 to 12 weeks of treatment or if the patient develops an unexpected fever. Patients taking HY-PO-TONE may produce a positive response to a direct antiglobulin test (Coombsu2019 test); if blood transfusion is required, prior knowledge of a positive direct antiglobulin test (Coombsu2019 test) reaction will aid cross-matching. HY-PO-TONE may occasionally cause urine to darken because of the breakdown of the medicine or its metabolites. Severe hypotension may occur during anaesthesia in patients being treated with HY-PO-TONE. The hypotensive effects may be diminished by sympathomimetics, imipramine and other tricyclic antidepressants and monoamine oxidase inhibitors.

HY-PO-TONE may interfere with the measurement of urinary uric acid by the phosphotungstate method and serum glutamic-pyruvic transaminase by the colorimetric method. Methyldopa fluoresces at the same wavelengths as catecholamines and may cause erratic reports of elevated urinary catecholamine concentrations. Severe hypotension may occur during anaesthesia in patients being treated with HY-PO-TONE. The hypotensive effects may be diminished by sympathomimetics, imipramine and other tricyclic antidepressants and monoamine oxidase inhibitors. When HY-PO-TONE and lithium are given concomitantly the patient should be monitored carefully for symptoms of lithium toxicity. The hypotensive effect of HY-PO-TONE may be diminished by sympathomimetics, phenothiazines, tricyclic antidepressants and MAOIs (see CONTRAINDICATIONS). The combination of HY-PO-TONE with other potentially hepatotoxic medicines, particularly halothane, is not advisable.

Pregnancy: The safety of HY-PO-TONE in pregnancy has not been established, as there are no adequate and well-controlled studies in pregnant women. HY-PO-TONE crosses the placenta and reduced blood pressure has been reported in infants born to mothers receiving HY-PO-TONE.

Lactating mothers: Methyldopa is distributed into breast milk in small amounts. The safety of HY-PO-TONE in lactation has not been established.

HY-PO-TONE may cause sedation, usually transient, may occur during the initial period of therapy or whenever the dose is increased. If affected, patients should not carry out activities where alertness is necessary, such as driving a car or operating machinery.

Blood and lymphatic system disorders: Less frequent: Thrombocytopenia, leucopenia, granulocytopenia and haemolytic anaemia. A positive response to the direct antiglobulin test (Coombsu2019 test) may occur in 10 % to 20 % of patients on prolonged therapy, usually without evidence of haemolysis.

Immune system disorders: Less frequent: Drug fever may occur within the first few weeks of therapy and may be accompanied by eosinophilia and abnormal liver function tests. Jaundice with or without fever may occur. It is advisable to take blood counts and to perform liver-function tests at intervals during the first 6 to 12 weeks of treatment or if the patient develops an unexplained fever.

Psychiatric disorders: Less frequent: Psychic effects, nightmares.

Nervous system disorders: Frequent: Headache, drowsiness (drowsiness occurs commonly in the first 2 or 3 days and usually decreases spontaneously or as a result of a reduction in the dosage). Less frequent: Depression, impaired mental acuity. Frequency unknown: Involuntary choreoathetotic movements have occurred in patients with severe bilateral cerebrovascular disease, Bellu2019s palsy, Parkinsonism.

Cardiovascular disorders: Frequent: Oedema. (Mass gain and oedema may be diminished by the concomitant administration of a thiazide diuretic such as hydrochlorothiazide). Less frequent: Bradycardia, postural hypotension (with associated weakness, dizziness, light-headedness), myocarditis. Frequency unknown: Aggravation of angina pectoris.

Gastrointestinal disorders: Frequent: Colitis, diarrhoea, nausea, pancreatitis. Frequency unknown: Salivary gland inflammation, black or sore tongue, constipation.

Hepatobiliary disorders: Less frequent: Liver damage may develop after long-term administration; fatal hepatic necrosis.

Skin disorders: Frequency unknown: Eczematous rashes and lichenoid and granulomatous skin eruptions have occurred.

Musculoskeletal disorders: Frequency unknown: Mild arthralgia, myalgia.

Renal disorders: Frequency unknown: Uraemia.

General disorders: Less frequent: A condition resembling systemic lupus erythematosus, disorders of sexual function, hyperprolactinaemia (with breast enlargement, lactation), nasal stuffiness.

Symptoms: Acute overdose may produce acute hypotension with other responses attributable to brain and gastrointestinal malfunction (excessive sedation, weakness, bradycardia, dizziness, lightheadedness, constipation, distention, flatus, diarrhoea, nausea, vomiting).

Treatment: If overdosage occurs the stomach should be emptied by aspiration and lavage. Treatment is largely symptomatic, but if necessary, intravenous infusions may be given to promote urinary excretion, and pressor medicines given cautiously. Methyldopa is dialysable.