The product labeling information includes all published material associated to a drug. Product labeling documents include information like generic names, active ingredients, ingredient strength dosage, routes of administration, appearance, usage, warnings, inactive ingredients, etc.
Hydrochlorothiazide USP is a diuretic and antihypertensive. It is the 3,4-dihydro derivative of chlorothiazide. It is chemically designated as 6-chloro-3,4-dihydro-2H-1,2,4-benzothiadiazine -7-sulfonamide 1,1-dioxide and has the following structural formula:Hydrochlorothiazide USP is a white, or practically white, crystalline powder which is slightly soluble in water, but freely soluble in sodium hydroxide solution, in n-butylamine, and in dimethylformamide; sparingly soluble in methanol, insoluble in ether, in chloroform, and in dilute mineral acids. Each tablet for oral administration contains 25 mg and 50 mg hydrochlorothiazide. In addition, each tablet contains the following inactive ingredients: FD&C yellow #6, Microcrystalline cellulose, lactose anhydrous, Sodium starch glycolate, Stearic acid and Magnesium stearate.
The mechanism of the antihypertensive effect of thiazides is unknown. Hydrochlorothiazide does not usually affect normal blood pressure. Hydrochlorothiazide affects the distal renal tubular mechanism of electrolyte reabsorption. At maximal therapeutic dosage all thiazides are approximately equal in their diuretic efficacy.Hydrochlorothiazide increases excretion of sodium and chloride in approximately equivalent amounts. Natriuresis may be accompanied by some loss of potassium and bicarbonate.After oral use diuresis begins within 2 hours, peaks in about 4 hours and lasts about 6 to12 hours.
Pharmacokinetics And Metabolism:
Hydrochlorothiazide is not metabolized but is eliminated rapidly by the kidney. When plasma levels have been followed for at least 24 hours, the plasma half-life has been observed to vary between 5.6 and 14.8 hours. At least 61 % of the oral dose is eliminated unchanged within 24 hours. Hydrochlorothiazide crosses the placental but not the blood-brain barrier and is excreted in breast milk.
Indications And Usage
Hydrochlorothiazide tablets USP are indicated as adjunctive therapy in edema associated with congestive heart failure, hepatic cirrhosis, and corticosteroid and estrogen therapy.Hydrochlorothiazide tablets USP have also been found useful in edema due to various forms of renal dysfunction such as nephrotic syndrome, acute glomerulonephritis, and chronic renal failure.Hydrochlorothiazide tablets USP are indicated in the management of hypertension either as the sole therapeutic agent or to enhance the effectiveness of other antihypertensive drugs in the more severe forms of hypertension.Use in pregnancy:Routine use of diuretics during normal pregnancy is inappropriate and exposes mother and fetus to unnecessary hazard. Diuretics do not prevent development of toxemia of pregnancy and there is no satisfactory evidence that they are useful in the treatment of toxemia.Edema during pregnancy may arise from pathologic causes or from the physiologic and mechanical consequences of pregnancy. Thiazides are indicated in pregnancy when edema is due to pathologic causes, just as they are in the absence of pregnancy (see PRECAUTIONS, Pregnancy). Dependent edema in pregnancy, resulting from restriction of venous return by the gravid uterus, is properly treated through elevation of the lower extremities and use of support stockings. Use of diuretics to lower intravascular volume in this instance is illogical and unnecessary. During normal pregnancy there is hypervolemia which is not harmful to the fetus or the mother in the absence of cardiovascular disease. However, it may be associated with edema, rarely generalized edema. If such edema causes discomfort, increased recumbency will often provide relief. Rarely this edema may cause extreme discomfort which is not relieved by rest. In these instances, a short course of diuretic therapy may provide relief and be appropriate.
Anuria. Hypersensitivity to this product or to other sulfonamide-derived drugs.
Use with caution in severe renal disease. In patients with renal disease, thiazides may precipitate azotemia. Cumulative effects of the drug may develop in patients with impaired renal function. Thiazides should be used with caution in patients with impaired hepatic function or progressive liver disease, since minor alterations of fluid and electrolyte balance may precipitate hepatic coma.Thiazides may add to or potentiate the action of other antihypertensive drugs.Sensitivity reactions may occur in patients with or without a history of allergy or bronchial asthma.The possibility of exacerbation or activation of systemic lupus erythematosus has been reported.Lithium generally should not be given with diuretics (see PRECAUTIONS, Drug Interactions).Acute Myopia and Secondary Angle-Closure GlaucomaHydrochlorothiazide, a sulfonamide, can cause an idiosyncratic reaction, resulting in acute transient myopia and acute angle-closure glaucoma. Symptoms include acute onset of decreased visual acuity or ocular pain and typically occur within hours to weeks of drug initiation., Untreated acute angle-closure glaucoma can lead to permanent vision loss. The primary treatment is to discontinue hydrochlorothiazide as rapidly as possible. Prompt medical or surgical treatments may need to be considered if the intraocular pressure remains uncontrolled. Risk factors for developing acute angle-closure glaucoma may include a history of sulfonamide or penicillin allergy.
The following adverse reactions have been reported and, within each category, are listed in order of decreasing severity.
The most common signs and symptoms observed are those caused by electrolyte depletion (hypokalemia, hypochloremia, hyponatremia) and dehydration resulting from excessive diuresis. If digitalis has also been administered, hypokalemia may accentuate cardiac arrhythmias.In the event of overdosage, symptomatic and supportive measures should be employed. Emesis should be induced or gastric lavage performed. Correct dehydration, electrolyte imbalance, hepatic coma and hypotension by established procedures. If required, give oxygen or artificial respiration for respiratory impairment. The degree to which hydrochlorothiazide is removed by hemodialysis has not been established.The oral LD50 of hydrochlorothiazide is greater than 10 g/kg in the mouse and rat.
Dosage And Administration
Therapy should be individualized according to patient response. Use the smallest dosage necessary to achieve the required response.
For Edema The usual adult dosage is 25 to 100 mg daily as a single or divided dose. Many patients with edema respond to intermittent therapy, i.e., administration on alternate days or on three to five days each week. With an intermittent schedule, excessive response and the resulting undesirable electrolyte imbalance are less likely to occur.For Control of HypertensionThe usual initial dose in adults is 25 mg daily given as a single dose. The dose may be increased to 50 mg daily, given as a single or two divided doses. Doses above 50 mg are often associated with marked reductions in serum potassium (see also PRECAUTIONS).Patients usually do not require doses in excess of 50 mg of hydrochlorothiazide daily when used concomitantly with other antihypertensive agents.
Infants And Children
For Diuresis and for Control of HypertensionThe usual pediatric dosage is 0.5 to 1 mg per pound (1 to 2 mg/kg) per day in single or two divided doses, not to exceed 37.5 mg per day in infants up to 2 years of age or 100 mg per day in children 2 to 12 years of age. In infants less than 6 months of age, doses up to 1.5 mg per pound (3 mg/kg) per day in two divided doses may be required. (See PRECAUTIONS, Pediatric Use)
Hydrochlorothiazide Tablets USP 25 mg are available as peach color, round, flat face, beveled edge, bisected tablets, debossed "EP" above bisect and "131" below bisect on one side and plain on the other side containing 25 mg of hydrochlorothioazide USP, packaged in:100 TABLET in a BOTTLE (53217-232-00)14 TABLET in a BOTTLE, PLASTIC (53217-232-14)30 TABLET in a BOTTLE, PLASTIC (53217-232-30)60 TABLET in a BOTTLE (53217-232-60)90 TABLET in a BOTTLE (53217-232-90)Dispense in a well-closed container as defined in the USP, with a child-resistant closure (as required).Store at 20°-25°C (68°-77°F) [See USP Controlled Room Temperature].KEEP THIS AND ALL MEDICATIONS OUT OF THE REACH OF CHILDREN.
* Please review the disclaimer below.