Metolazone

DOSAGE AND ADMINISTRATION

Effective dosage of metolazone tablets should be individualized according to indication and patient response. A single daily dose is recommended. Therapy with metolazone tablets should be titrated to gain an initial therapeutic response and to determine the minimal dose possible to maintain the desired therapeutic response.

Usual Single Daily Dosage Schedules Suitable initial dosages will usually fall in the ranges given.

Edema of cardiac failure:

Metolazone tablets, 5 mg to 20 mg once daily.

Edema of renal disease:

Metolazone tablets, 5 mg to 20 mg once daily. 5 mg to 5 mg once daily. 5 mg) once daily and increasing to two tablets (1 mg) once daily if needed. Treatment of Edematous States The time interval required for the initial dosage to produce an effect may vary.

Diuresis and saluresis usually begin within one hour and persist for 24 hours or longer. When a desired therapeutic effect has been obtained, it may be advisable to reduce the dose if possible. The daily dose depends on the severity of the patient's condition, sodium intake, and responsiveness.

A decision to change the daily dose should be based on the results of thorough clinical and laboratory evaluations. If antihypertensive drugs or diuretics are given concurrently with metolazone, more careful dosage adjustment may be necessary.

For patients who tend to experience paroxysmal nocturnal dyspnea, it may be advisable to employ a larger dose to ensure prolongation of diuresis and saluresis for a full 24-hour period. Treatment of Hypertension The time interval required for the initial dosage regimen to show effect may vary from three or four days to three to six weeks in the treatment of elevated blood pressure.

Doses should be adjusted at appropriate intervals to achieve maximum therapeutic effect.

ADVERSE REACTIONS

Metolazone is usually well tolerated and most reported adverse reactions have been mild and transient. Many metolazone related adverse reactions represent extensions of its expected pharmacologic activity and can be attributed to either its antihypertensive action or its renal/metabolic actions.

The following adverse reactions have been reported. Several are single or comparably rare occurrences. Adverse reactions are listed in decreasing order of severity within body systems. Cardiovascular Chest pain/discomfort, orthostatic hypotension, excessive volume depletion, hemoconcentration, venous thrombosis, palpitations.

Central and Peripheral Nervous System Syncope, neuropathy, vertigo, paresthesias, psychotic depression, impotence, dizziness/lightheadedness, drowsiness, fatigue, weakness, restlessness (sometimes resulting in insomnia), headache. Dermatologic/Hypersensitivity Toxic epidermal necrolysis (TEN), Stevens-Johnson syndrome, necrotizing angiitis (cutaneous vasculitis), skin necrosis, purpura, petechiae, dermatitis (photosensitivity), urticaria, pruritus, skin rashes.

Gastrointestinal Hepatitis, intrahepatic cholestatic jaundice, pancreatitis, vomiting, nausea, epigastric distress, diarrhea, constipation, anorexia, abdominal bloating, abdominal pain. Hematologic Aplastic/hypoplastic anemia, agranulocytosis, leukopenia, thrombocytopenia.

Metabolic Hypokalemia, hyponatremia, hyperuricemia, hypochloremia, hypochloremic alkalosis, hyperglycemia, glycosuria, increase in serum urea nitrogen (BUN) or creatinine, hypophosphatemia, hypomagnesemia, hypercalcemia. Musculoskeletal Joint pain, acute gouty attacks, muscle cramps or spasm.

Other Transient blurred vision, chills, dry mouth. In addition, adverse reactions reported with similar antihypertensive-diuretics, but which have not been reported to date for metolazone include: bitter taste, sialadenitis, xanthopsia, respiratory distress (including pneumonitis) and anaphylactic reactions.

WARNINGS

Rapid Onset Hyponatremia and/or Hypokalemia Rarely, the rapid onset of severe hyponatremia and/or hypokalemia has been reported following initial doses of thiazide and non-thiazide diuretics. When symptoms consistent with severe electrolyte imbalance appear rapidly, drug should be discontinued and supportive measures should be initiated immediately.

Parenteral electrolytes may be required. Appropriateness of therapy with this class of drugs should be carefully reevaluated. Hypokalemia Hypokalemia may occur with consequent weakness, cramps and cardiac dysrhythmias. Serum potassium should be determined at regular and appropriate intervals and dose reduction, potassium supplementation or addition of a potassium-sparing diuretic instituted whenever indicated.

Hypokalemia is a particular hazard in patients who are digitalized or who have or have had a ventricular arrhythmia; dangerous or fatal arrhythmias may be precipitated. Hypokalemia is dose related. Concomitant Therapy Lithium In general, diuretics should not be given concomitantly with lithium because they reduce its renal clearance and add a high risk of lithium toxicity.

Read prescribing information for lithium preparations before use of such concomitant therapy. Furosemide Unusually large or prolonged losses of fluids and electrolytes may result when metolazone is administered concomitantly to patients receiving furosemide (see PRECAUTIONS, Drug Interactions ).

Other Antihypertensive Drugs When metolazone is used with other antihypertensive drugs, particular care must be taken to avoid excessive reduction of blood pressure, especially during initial therapy. Cross-Allergy Cross-allergy may occur when metolazone is given to patients known to be allergic to sulfonamide-derived drugs, thiazides, or quinethazone.

, angioedema, bronchospasm) may occur with or without a history of allergy or bronchial asthma and may occur with the first dose of metolazone.

CONTRAINDICATIONS

Anuria, hepatic coma or precoma, known allergy or hypersensitivity to metolazone.