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PRECAUTIONS General Derangements of Serum Electrolytes: In clinical trials of fosinopril monotherapy, hyperkalemia (serum potassium at least 10% greater than the upper limit of normal) occurred in approximately 2.6% of hypertensive patients receiving fosinopril. In most cases, these were isolated values which resolved despite continued therapy. Risk factors for the development of hyperkalemia included renal insufficiency, diabetes mellitus, and the concomitant use of potassium-sparing diuretics, potassium supplements, and/or potassium-containing salt substitutes. Conversely, treatment with thiazide diuretics has been associated with hypokalemia, hyponatremia, and hypochloremic alkalosis. These disturbances have sometimes been manifest as one or more of dryness of mouth, thirst, weakness, lethargy, drowsiness, restlessness, muscle pains or cramps, muscular fatigue, hypotension, oliguria, tachycardia, nausea, and vomiting. Hypokalemia can also sensitize or exaggerate the response of the heart to the toxic effects of digitalis. The risk of hypokalemia is greatest in patients with cirrhosis of the liver, in patients experiencing a brisk diuresis, in patients who are receiving inadequate oral intake of electrolytes, and in patients receiving concomitant therapy with corticosteroids or ACTH. The opposite effects of fosinopril and hydrochlorothiazide on serum potassium will approximately balance each other in many patients, so that no net effect upon serum potassium will be seen. In other patients, one or the other effect may be dominant. Initial and periodic determinations of serum electrolytes to detect possible electrolyte imbalance should be performed at appropriate intervals. Chloride deficits are generally mild and require specific treatment only under extraordinary circumstances (e.g., in liver disease or renal disease). Dilutional hyponatremia may occur in edematous patients; appropriate therapy is water restriction rather than administration of salt, except in rare instances when the hyponatremia is life-threatening. In actual salt depletion, appropriate replacement is the therapy of choice. Calcium excretion is decreased by thiazides. In a few patients on prolonged thiazide therapy, pathological changes in the parathyroid gland have been observed, with hypercalcemia and hypophosphatemia. More serious complications of hyperparathyroidism (renal lithiasis, bone resorption, and peptic ulceration) have not been seen. Thiazides increase the urinary excretion of magnesium, and hypomagnesemia may result. Other Metabolic Disturbances: Thiazide diuretics tend to reduce glucose tolerance and to raise serum levels of cholesterol, triglycerides, and uric acid. These effects are usually minor, but frank gout or overt diabetes may be precipitated in susceptible patients. Cough: Presumably due to the inhibition of the degradation of endogenous bradykinin, persistent nonproductive cough has been reported with all ACE inhibitors, always resolving after discontinuation of therapy. ACE inhibitor-induced cough should be considered in the differential diagnosis of cough. Surgery/Anesthesia: In patients undergoing surgery or during anesthesia with agents that produce hypotension, fosinopril will block the angiotensin II formation that could otherwise occur secondary to compensatory renin release. Hypotension that occurs as a result of this mechanism can be corrected by volume expansion. Information for Patients Angioedema: Angioedema, including laryngeal edema, can occur with treatment with ACE inhibitors, especially following the first dose. A patient receiving MONOPRIL-HCT should be told to report immediately any signs or symptoms suggesting angioedema (swelling of face, eyes, lips, or tongue, or difficulty in breathing) and to take no more drug until after consulting with the prescribing physician. Pregnancy: Female patients of childbearing age should be told about the consequences of second- and third-trimester exposure to ACE inhibitors, and they should also be told that these consequences do not appear to have resulted from intrauterine ACE inhibitor exposure that has been limited to the first trimester. These patients should be asked to report pregnancies to their physicians as soon as possible. Symptomatic Hypotension: A patient receiving MONOPRIL-HCT (fosinopril sodium-hydrochlorothiazide tablets) should be cautioned that lightheadedness can occur, especially during the first days of therapy, and that it should be reported to the prescribing physician. The patients should be told that if syncope occurs, MONOPRIL-HCT should be discontinued until the physician has been consulted. All patients should be cautioned that inadequate fluid intake, excessive perspiration, diarrhea, or vomiting can lead to an excessive fall in blood pressure, with the same consequences of lightheadedness and possible syncope. Hyperkalemia: A patient receiving MONOPRIL-HCT should be told not to use potassium supplements or salt substitutes containing potassium without consulting the prescribing physician. Neutropenia: Patients should be told to promptly report any indication of infection (e.g., sore throat, fever), which could be a sign of neutropenia. Laboratory Tests Therapy with MONOPRIL-HCT should be interrupted for a few days before carrying out tests of parathyroid function. Fosinopril may cause false low measurement of serum digoxin levels when the Digi-Tab ® (Nuclear Medical) RIA Kit is used. The accuracy of the Coat-A-Count ® (Diagnostic Products Corporation) kit is not affected. Drug Interactions Potassium supplements and potassium-sparing diuretics: As noted above (“Derangements of Serum Electrolytes”), the net effect of MONOPRIL-HCT may be to elevate a patient’s serum potassium, to reduce it, or to leave it unchanged. Potassium-sparing diuretics (spironolactone, amiloride, triamterene, and others) or potassium supplements can increase the risk of hyperkalemia. If concomitant use of such agents is indicated, they should be given with caution, and the patient’s serum potassium should be monitored frequently. Lithium: Increased serum lithium levels and symptoms of lithium toxicity have been reported in patients receiving ACE inhibitors during therapy with lithium. Because renal clearance of lithium is reduced by thiazides, the risk of lithium toxicity is presumably raised further when, as in therapy with MONOPRIL-HCT (fosinopril sodium-hydrochlorothiazide tablets), a thiazide diuretic is coadministered with the ACE inhibitor. MONOPRIL-HCT and lithium should be coadministered with caution, and frequent monitoring of serum lithium levels is recommended. Antacids: In a clinical pharmacology study, serum levels and urinary excretion of fosinoprilat were reduced when fosinopril was coadministered with an antacid (aluminum hydroxide, magnesium hydroxide, and simethicone) suggesting that antacids may impair absorption of fosinopril. If concomitant administration of these agents is indicated, dosing should be separated by 2 hours. Gold: Nitritoid reactions (symptoms include facial flushing, nausea, vomiting, and hypotension) have been reported rarely in patients on therapy with injectable gold (sodium aurothiomalate) and concomitant ACE inhibitor therapy including MONOPRIL-HCT. Other: The bioavailability of unbound fosinoprilat is not altered by coadministration of fosinopril with aspirin , chlorthalidone , cimetidine , digoxin , metoclopramide , nifedipine , propranolol , propantheline , or warfarin . Other ACE inhibitors have had less than additive effects with beta-adrenergic blockers , presumably because drugs of both classes lower blood pressure by inhibiting parts of the renin-angiotensin system. Interaction studies with warfarin have failed to identify any clinically important effects of fosinopril on the serum concentration or clinical effects of the anticoagulant. Insulin requirements in diabetic patients may be increased, decreased, or unchanged. Thiazides may decrease arterial responsiveness to norepinephrine , but not enough to preclude effectiveness of the pressor agent for therapeutic use. Thiazides may increase the responsiveness to tubocurarine . The diuretic, natriuretic, and antihypertensive effects of thiazide diuretics may be reduced by concurrent administration of nonsteroidal anti-inflammatory agents ; the effects (if any) of these agents on the antihypertensive effect of MONOPRIL-HCT have not been studied. By alkalinizing the urine, hydrochlorothiazide may decrease the effectiveness of methenamine . Cholestyramine and colestipol resins: Absorption of hydrochlorothiazide is impaired in the presence of anionic exchange resins. Single doses of either cholestyramine or colestipol resins bind the hydrochlorothiazide and reduce its absorption from the gastrointestinal tract by up to 85% and 43%, respectively. Carcinogenesis, Mutagenesis, Impairment of Fertility Fosinopril-Hydrochlorothiazide: Reproductive studies and long-term carcinogenicity studies with MONOPRIL-HCT have not been conducted. The combination of fosinopril and hydrochlorothiazide was not mutagenic in the Ames microbial mutagen test, the mouse lymphoma forward mutation assay, or the Chinese hamster ovary cell cytogenetic assay. The combination was also not genotoxic in a mouse micronucleus test in vivo . Fosinopril Sodium: No evidence of a carcinogenicity was found when fosinopril was given in the diet to rats and mice for up to 24 months at doses up to 400 mg/kg/day. On a body weight basis, the highest dose was about 250 times the maximum human dose of 80 mg, given to a 50 kg subject. On a body surface area basis, this dose is 20 (mice) to 40 (rats) times the maximum human dose. Neither fosinopril nor the fosinoprilat moiety was mutagenic in the Ames microbial mutagen test, the mouse lymphoma forward mutation assay, or a mitotic gene conversion assay. Fosinopril was also not genotoxic in a mouse micronucleus test in vivo and a mouse bone marrow cytogenetic assay in vivo . In Chinese hamster ovary cell cytogenetic assay, fosinopril increased the frequency of chromosomal aberrations when tested without metabolic activation at a concentration that was toxic to the cells. However, there was no increase in chromosomal aberrations at lower drug concentrations without metabolic activation or at any concentration with metabolic activation. There were no adverse reproductive effects in male and female rats treated with up to 60 mg/kg daily. At doses 4 times higher, slight increases in pairing time were seen. This higher dose is about 125 (body surface area basis) or 600 (body weight basis) times greater than the dose received by a 50 kg human receiving 20 mg a day. Hydrochlorothiazide: Under the auspices of the National Toxicology Program, rats and mice received hydrochlorothiazide for two years at doses up to 100 (rats) and 600 (mice) mg/kg/day. On a body weight basis, these highest doses were about 2400 times (mice) or 400 times (rats) the MONOPRIL-HCT dose of 12.5 mg, given to a 50 kg subject. On a body surface area basis, these doses are 226 times (mice) and 82 times (rats) the MONOPRIL-HCT dose. These studies uncovered no evidence of carcinogenicity in rats or female mice, but there was equivocal evidence of hepatocarcinogenicity in male mice. Hydrochlorothiazide was not genotoxic in in vitro assays using strains TA 98, TA 100, TA 1535, TA 1537, and TA 1538 of Salmonella typhimurium (Ames assay); in the Chinese Hamster Ovary (CHO) test for chromosomal aberrations; or in in vivo assays using mouse germinal cell chromosomes; Chinese Hamster bone-marrow chromosomes, and the Drosophila sex-linked recessive lethal trait gene. Using concentrations of hydrochlorothiazide of 43–1300 mg/mL, positive test results were obtained in the in vitro CHO Sister Chromatid Exchange (clastogenicity) test and in the Mouse Lymphoma Cell (mutagenicity) assays. Using an unspecified concentration of hydrochlorothiazide, positive test results were also obtained in the Aspergillus nidulans nondisjunction assay. No adverse effects upon fertility were seen when rats and mice received dietary hydrochlorothiazide prior to mating and throughout gestation at doses up to 4 (rats) and 100 (mice) mg/kg/day. These doses are from 3.2 (body surface area basis in rats) to 400 (weight basis in mice) times greater than the dose received by a 50 kg human receiving 12.5 mg a day. Pregnancy Pregnancy Categories C (first trimester) and D (second and third trimesters) See WARNINGS: Fetal/Neonatal Morbidity and Mortality . Nursing Mothers Both fosinopril and hydrochlorothiazide are excreted in human milk. Because of the potential for serious adverse reactions in nursing infants, a decision should be made whether to discontinue nursing or to discontinue MONOPRIL-HCT, taking into account the importance of the drug to the mother. Geriatric Use Clinical studies of fosinopril sodium-hydrochlorothiazide did not include sufficient numbers of subjects aged 65 and over to determine whether they respond differently from younger subjects. Other reported clinical experience has not identified differences in responses between elderly and younger patients. In general, dose selection for an elderly patient should be cautious, usually starting at the low end of the dosing range, reflecting the greater frequency of decreased hepatic, renal, or cardiac function, and of concomitant disease or other drug therapy. Pediatric Use Safety and effectiveness in pediatric patients have not been established.