displayName: DESCRIPTION SECTION
FDA Article Code: 34089-3
Hydrochlorothiazide capsules 12.5 mg is the 3,4-dihydro derivative of chlorothiazide. Its chemical name is 6-Chloro-3,4-dihydro-2 H -1 ,2,4-benzothiadiazine-7- sulfonamide 1,1-dioxide. Its empirical formula is C H ClN O S ;its molecular weight is 297.74; and its structural formula is
It is a white, or practically white, crystalline powder which is slightly soluble in water, but freely soluble in sodium hydroxide solution.
Hydrochlorothiazide is supplied as 12.5 mg capsules for oral use. Each capsule contains the following inactive ingredients: colloidal silicon dioxide, D&C Yellow #10, FD&C Blue #1, FD&C Blue #2, FD&C Red #40, gelatin, iron oxide black, lactose monohydrate, magnesium stearate, pregelatinized starch, propylene glycol, shellac, and titanium dioxide.
displayName: CLINICAL PHARMACOLOGY SECTION
FDA Article Code: 34090-1
Hydrochlorothiazide blocks the reabsorption of sodium and chloride ions, and it thereby increases the quantity of sodium traversing the distal tubule and the volume of water excreted. A portion of the additional sodium presented to the distal tubule is exchanged there for potassium and hydrogen ions. With continued use of hydrochlorothiazide and depletion of sodium, compensatory mechanisms tend to increase this exchange and may produce excessive loss of potassium, hydrogen and chloride ions. Hydrochlorothiazide also decreases the excretion of calcium and uric acid, may increase the excretion of iodide and may reduce glomerular filtration rate. Metabolic toxicities associated with excessive electrolyte changes caused by hydrochlorothiazide have been shown to be dose-related.
INDICATIONS & USAGE
displayName: INDICATIONS & USAGE SECTION
FDA Article Code: 34067-9
Hydrochlorothiazide capsules are indicated in the management of hypertension either as the sole therapeutic agent, or in combination with other antihypertensives.
Unlike potassium sparing combination diuretic products, Hydrochlorothiazide capsules may be used in those patients in whom the development of hyperkalemia cannot be risked, including patients taking ACE inhibitors.
displayName: CONTRAINDICATIONS SECTION
FDA Article Code: 34070-3
Hydrochlorothiazide capsules are contraindicated in patients with anuria. Hypersensitivity to this product or other sulfonamide derived drugs is also contraindicated.
displayName: WARNINGS SECTION
FDA Article Code: 34071-1
Acute Myopia and Secondary Angle-Closure Glaucoma
Hydrochlorothiazide, 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.
Latent diabetes mellitus may become manifest and diabetic patients given thiazides may require adjustment of their insulin dose.
Diabetes and Hypoglycemia:
Cumulative effects of the thiazides may develop in patients with impaired renal function. In such patients, thiazides may precipitate azotemia.
displayName: PRECAUTIONS SECTION
FDA Article Code: 42232-9
In published studies, clinically significant hypokalemia has been consistently less common in patients who received 12.5 mg of hydrochlorothiazide than in patients who received higher doses. Nevertheless, periodic determination of serum electrolytes should be performed in patients who may be at risk for the development of hypokalemia. Patients should be observed for signs of fluid or electrolyte disturbances, i.e. hyponatremia, hypochloremic alkalosis, and hypokalemia and hypomagnesemia.
Electrolyte and Fluid Balance Status:
Warning signs or symptoms of fluid and electrolyte imbalance include dryness of mouth, thirst, weakness, lethargy, drowsiness, restlessness, muscle pains or cramps, muscular fatigue, hypotension, oliguria, tachycardia, and gastrointestinal disturbances such as nausea and vomiting.
Hypokalemia may develop, especially with brisk diuresis when severe cirrhosis is present, during concomitant use of corticosteroid or adrenocorticotropic hormone (ACTH) or after prolonged therapy. Interference with adequate oral electrolyte intake will also contribute to hypokalemia. Hypokalemia and hypomagnesemia can provoke ventricular arrhythmias or sensitize or exaggerate the response of the heart to the toxic effects of digitalis. Hypokalemia may be avoided or treated by potassium supplementation or increased intake of potassium rich foods.
Dilutional hyponatremia is life-threatening and may occur in edematous patients in hot weather; appropriate therapy is water restriction rather than salt administration, except in rare instances when the hyponatremia is life-threatening. In actual salt depletion, appropriate replacement is the therapy of choice.
Hyperuricemia or acute gout may be precipitated in certain patients receiving thiazide diuretics.
Thiazides should be used with caution in patients with impaired hepatic function. They can precipitate hepatic coma in patients with severe liver disease.
Impaired Hepatic Function:
Calcium excretion is decreased by thiazides, and pathologic changes in the parathyroid glands, with hypercalcemia and hypophosphatemia, have been observed in a few patients on prolonged thiazide therapy.
When given concurrently the following drugs may interact with thiazide diuretics:
— potentiation of orthostatic hypotension may occur.
Alcohol, barbiturates, or narcotics
(oral agents and insulin) dosage adjustment of the antidiabetic drug may be required.
Antidiabetic drugs —
— additive effect or potentiation.
Other antihypertensive drugs
— Cholestyramine and colestipol resins bind the hydrochlorothiazide and reduce its absorption from the gastrointestinal tract by up to 85 and 43 percent, respectively.
Cholestyramine and colestipol resins
intensified electrolyte depletion, particularly hypokalemia.
Corticosteroid, ACTH —
— possible decreased response to pressor amines but not sufficient to preclude their use.
Pressor amines (e.g., norepinephrine)
— possible increased responsiveness to the muscle relaxant.
Skeletal muscle relaxants, nondepolarizing (e.g., tubocurarine)
— generally should not be given with diuretics. Diuretic agents reduce the renal clearance of lithium and greatly increase the risk of lithium toxicity. Refer to the package insert for lithium preparations before use of such preparations with Hydrochlorothiazide.
— In some patients, the administration of a non-steroidal anti-inflammatory agent can reduce the diuretic, natriuretic, and anti-hypertensive effects of loop, potassium-sparing and thiazide diuretics. When Hydrochlorothiazide and non-steroidal anti-inflammatory agents are used concomitantly, the patients should be observed closely to determine if the desired effect of the diuretic is obtained.
Non-steroidal anti-inflammatory drugs
— Thiazides should be discontinued before carrying out tests for parathyroid function (see
Drug/Laboratory Test Interactions
Two-year feeding studies in mice and rats conducted under the auspices of the National Toxicology Program (NTP) uncovered no evidence of a carcinogenic potential of hydrochlorothiazide in female mice (at doses of up to approximately 600 mg/kg/day) or in male and female rats (at doses of approximately 100 mg/kg/day). The NTP, however, found equivocal evidence for hepatocarcinogenicity in male mice. Hydrochlorothiazide was not genotoxic in vitro in the Ames mutagenicity assay of Salmonella typhimurium strains TA 98, TA 100, TA 1535, TA 1537, and TA 1538 and in the Chinese Hamster Ovary (CHO) test for chromosomal aberrations, or in vivo in assays using mouse germinal cell chromosomes, Chinese hamster bone marrow chromosomes, and the Drosophila sex-linked recessive lethal trait gene. Positive test results were obtained only in the in vitro CHO Sister Chromatid Exchange (clastogenicity) and in the Mouse Lymphoma Cell (mutagenicity) assays, using concentrations of hydrochlorothiazide from 43 to 1300 mcg/mL, and in the Aspergillus nidulans non-disjunction assay at an unspecified concentration.
Carcinogenesis, Mutagenesis, Impairment of Fertility:
Hydrochlorothiazide had no adverse effects on the fertility of mice and rats of either sex in studies wherein these species were exposed, via their diet, to doses of up to 100 and 4 mg/kg, respectively, prior to conception and throughout gestation.
displayName: ADVERSE REACTIONS SECTION
FDA Article Code: 34084-4
The adverse reactions associated with hydrochlorothiazide have been shown to be dose related. In controlled clinical trials, the adverse events reported with doses of 12.5 mg hydrochlorothiazide once daily were comparable to placebo. The following adverse reactions have been reported for doses of hydrochlorothiazide 25 mg and greater and, within each category, are listed in the order of decreasing severity.
Body as a whole:
Hypotension including orthostatic hypotension (may be aggravated by alcohol, barbiturates, narcotics or antihypertensive drugs).
Pancreatitis, jaundice (intrahepatic cholestatic jaundice), diarrhea, vomiting, sialadenitis, cramping, constipation, gastric irritation, nausea, anorexia.
Aplastic anemia, agranulocytosis, leukopenia, hemolytic anemia, thrombocytopenia.
Anaphylactic reactions, necrotizing angiitis (vasculitis and cutaneous vasculitis), respiratory distress including pneumonitis and pulmonary edema, photosensitivity, fever, urticaria, rash, purpura.
Electrolyte imbalance (see ), hyperglycemia, glycosuria, hyperuricemia.
Vertigo, paresthesia, dizziness, headache, restlessness.
Renal failure, renal dysfunction, interstitial nephritis (see
Erythema multiforme including Stevens-Johnson syndrome, exfoliative dermatitis including toxic epidermal necrolysis, alopecia.
Transient blurred vision, xanthopsia.
Whenever adverse reactions are moderate or severe, thiazide dosage should be reduced or therapy withdrawn.
displayName: OVERDOSAGE SECTION
FDA Article Code: 34088-5
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 LD of hydrochlorothiazide is greater than 10 g/kg in the mouse and rat.
DOSAGE AND ADMINISTRATION
displayName: DOSAGE & ADMINISTRATION SECTION
FDA Article Code: 34068-7
The adult initial dose of Hydrochlorothiazide is one capsule given once daily whether given alone or in combination with other anti-hypertensives. Total daily doses greater than 50 mg are not recommended.
For Control of Hypertension:
displayName: HOW SUPPLIED SECTION
FDA Article Code: 34069-5
NDC:50436-6733-1 in a BOTTLE of 30 CAPSULE, GELATIN COATEDS
NDC:50436-6733-3 in a BOTTLE of 90 CAPSULE, GELATIN COATEDS
HCTZ 12.5MG CAP
displayName: PACKAGE LABEL.PRINCIPAL DISPLAY PANEL
FDA Article Code: 51945-4