Quinapril

INDICATIONS AND USAGE Hypertension Quinapril tablets, USP are indicated for the treatment of hypertension, to lower blood pressure. Lowering blood pressure reduces the risk of fatal and nonfatal cardiovascular events, primarily strokes and myocardial infarctions. These benefits have been seen in controlled trials of antihypertensive drugs from a wide variety of pharmacologic classes including the class to which this drug principally belongs. There are no controlled trials demonstrating risk reduction with quinapril tablets, USP. Control of high blood pressure should be part of comprehensive cardiovascular risk management, including, as appropriate, lipid control, diabetes management, antithrombotic therapy, smoking cessation, exercise, and limited sodium intake. Many patients will require more than one drug to achieve blood pressure goals. For specific advice on goals and management, see published guidelines, such as those of the National High Blood Pressure Education Program's Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure (JNC). Numerous antihypertensive drugs, from a variety of pharmacologic classes and with different mechanisms of action, have been shown in randomized controlled trials to reduce cardiovascular morbidity and mortality, and it can be concluded that it is blood pressure reduction, and not some other pharmacologic property of the drugs, that is largely responsible for those benefits. The largest and most consistent cardiovascular outcome benefit has been a reduction in the risk of stroke, but reductions in myocardial infarction and cardiovascular mortality also have been seen regularly. Elevated systolic or diastolic pressure causes increased cardiovascular risk, and the absolute risk increase per mmHg is greater at higher blood pressures, so that even modest reductions of severe hypertension can provide substantial benefit. Relative risk reduction from blood pressure reduction is similar across populations with varying absolute risk, so the absolute benefit is greater in patients who are at higher risk independent of their hypertension (for example, patients with diabetes or hyperlipidemia), and such patients would be expected to benefit from more aggressive treatment to a lower blood pressure goal. Some antihypertensive drugs have smaller blood pressure effects (as monotherapy) in black patients, and many antihypertensive drugs have additional approved indications and effects (e.g., on angina, heart failure, or diabetic kidney disease). These considerations may guide selection of therapy. Quinapril tablets, USP may be used alone or in combination with thiazide diuretics . Heart Failure Quinapril tablets, USP are indicated in the management of heart failure as adjunctive therapy when added to conventional therapy including diuretics and/or digitalis. In using quinapril tablets, USP consideration should be given to the fact that another ACE inhibitor, captopril, has caused agranulocytosis, particularly in patients with renal impairment or collagen vascular disease. Available data are insufficient to show that quinapril tablets, USP do not have a similar risk (see WARNINGS ). Angioedema in black patients: Black patients receiving ACE inhibitor monotherapy have been reported to have a higher incidence of angioedema compared to non-blacks. It should also be noted that in controlled clinical trials ACE inhibitors have an effect on blood pressure that is less in black patients than in non-blacks.

DOSAGE AND ADMINISTRATION Hypertension Monotherapy The recommended initial dosage of quinapril tablets in patients not on diuretics is 10 or 20 mg once daily. Dosage should be adjusted according to blood pressure response measured at peak (2 to 6 hours after dosing) and trough (predosing). Generally, dosage adjustments should be made at intervals of at least 2 weeks. Most patients have required dosages of 20, 40, or 80 mg/day, given as a single dose or in two equally divided doses. In some patients treated once daily, the antihypertensive effect may diminish toward the end of the dosing interval. In such patients an increase in dosage or twice daily administration may be warranted. In general, doses of 40 to 80 mg and divided doses give a somewhat greater effect at the end of the dosing interval. Concomitant Diuretics If blood pressure is not adequately controlled with quinapril tablets monotherapy, a diuretic may be added. In patients who are currently being treated with a diuretic, symptomatic hypotension occasionally can occur following the initial dose of quinapril tablets. To reduce the likelihood of hypotension, the diuretic should, if possible, be discontinued 2 to 3 days prior to beginning therapy with quinapril tablets (see WARNINGS ). Then, if blood pressure is not controlled with quinapril tablets alone, diuretic therapy should be resumed. If the diuretic cannot be discontinued, an initial dose of 5 mg quinapril tablets should be used with careful medical supervision for several hours and until blood pressure has stabilized. The dosage should subsequently be titrated (as described above) to the optimal response (see WARNINGS , PRECAUTIONS and Drug Interactions ). Renal Impairment Kinetic data indicate that the apparent elimination half-life of quinaprilat increases as creatinine clearance decreases. Recommended starting doses, based on clinical and pharmacokinetic data from patients with renal impairment, are as follows: Creatinine Clearance Maximum Recommended Initial Dose >60 mL/min 10 mg 30 to 60 mL/min 5 mg 10 to 30 mL/min 2.5 mg <10 mL/min Insufficient data for dosage recommendation Patients should subsequently have their dosage titrated (as described above) to the optimal response. Elderly (≥65 years) The recommended initial dosage of quinapril tablets in elderly patients is 10 mg given once daily followed by titration (as described above) to the optimal response. Heart Failure Quinapril tablets are indicated as adjunctive therapy when added to conventional therapy including diuretics and/or digitalis. The recommended starting dose is 5 mg twice daily. This dose may improve symptoms of heart failure, but increases in exercise duration have generally required higher doses. Therefore, if the initial dosage of quinapril tablets is well tolerated, patients should then be titrated at weekly intervals until an effective dose, usually 20 to 40 mg daily given in two equally divided doses, is reached or undesirable hypotension, orthostatis, or azotemia (see WARNINGS ) prohibit reaching this dose. Following the initial dose of quinapril tablets, the patient should be observed under medical supervision for at least two hours for the presence of hypotension or orthostatis and, if present, until blood pressure stabilizes. The appearance of hypotension, orthostatis, or azotemia early in dose titration should not preclude further careful dose titration. Consideration should be given to reducing the dose of concomitant diuretics. DOSE ADJUSTMENTS IN PATIENTS WITH HEART FAILURE AND RENAL IMPAIRMENT OR HYPONATREMIA Pharmacokinetic data indicate that quinapril elimination is dependent on level of renal function. In patients with heart failure and renal impairment, the recommended initial dose of quinapril tablets is 5 mg in patients with a creatinine clearance above 30 mL/min and 2.5 mg in patients with a creatinine clearance of 10 to 30 mL/min. There is insufficient data for dosage recommendation in patients with a creatinine clearance less than 10 mL/min (see DOSAGE AND ADMINISTRATION , Heart Failure , WARNINGS , and PRECAUTIONS, Drug Interactions ). If the initial dose is well tolerated, quinapril tablets may be administered the following day as a twice daily regimen. In the absence of excessive hypotension or significant deterioration of renal function, the dose may be increased at weekly intervals based on clinical and hemodynamic response.

WARNING: FETAL TOXICITY • When pregnancy is detected, discontinue quinapril as soon as possible. • Drugs that act directly on the renin-angiotensin system can cause injury and death to the developing fetus. See Warnings: Fetal Toxicity WARNINGS Anaphylactoid and Possibly Related Reactions Presumably because ACE inhibitors affect the metabolism of eicosanoids and polypeptides, including endogenous bradykinin, patients receiving ACE inhibitors (including quinapril) may be subject to a variety of adverse reactions, some of them serious. Head and Neck Angioedema : Angioedema of the face, extremities, lips, tongue, glottis, and larynx has been reported in patients treated with ACE inhibitors and has been seen in 0.1% of patients receiving quinapril. In two similarly sized U.S. postmarketing trials that, combined, enrolled over 3,000 black patients and over 19,000 non-blacks, angioedema was reported in 0.30% and 0.55% of blacks (in study 1 and 2 respectively) and 0.39% and 0.17% of non-blacks. Angioedema associated with laryngeal edema can be fatal. If laryngeal stridor or angioedema of the face, tongue, or glottis occurs, treatment with quinapril should be discontinued immediately, the patient treated in accordance with accepted medical care, and carefully observed until the swelling disappears. In instances where swelling is confined to the face and lips, the condition generally resolves without treatment; antihistamines may be useful in relieving symptoms. Where there is involvement of the tongue, glottis, or larynx likely to cause airway obstruction, emergency therapy including, but not limited to, subcutaneous epinephrine solution 1:1000 (0.3 to 0.5 mL) should be promptly administered (see ADVERSE REACTIONS ). Patients taking concomitant mammalian target of rapamycin (mTOR) inhibitor (e.g., temsirolimus) therapy or a neprilysin inhibitor may be at increased risk for angioedema. Intestinal Angioedema : Intestinal angioedema has been reported in patients treated with ACE inhibitors. These patients presented with abdominal pain (with or without nausea or vomiting); in some cases there was no prior history of facial angioedema and C-1 esterase levels were normal. The angioedema was diagnosed by procedures including abdominal CT scan or ultrasound, or at surgery, and symptoms resolved after stopping the ACE inhibitor. Intestinal angioedema should be included in the differential diagnosis of patients on ACE inhibitors presenting with abdominal pain. Patients with a history of angioedema : Patients with a history of angioedema unrelated to ACE inhibitor therapy may be at increased risk of angioedema while receiving an ACE inhibitor (see also CONTRAINDICATIONS ). Anaphylactoid reactions during desensitization : Two patients undergoing desensitizing treatment with hymenoptera venom while receiving ACE inhibitors sustained life-threatening anaphylactoid reactions. In the same patients, these reactions were avoided when ACE inhibitors were temporarily withheld, but they reappeared upon inadvertent rechallenge. Anaphylactoid reactions during membrane exposure : Anaphylactoid reactions have been reported in patients dialyzed with high-flux membranes and treated concomitantly with an ACE inhibitor. Anaphylactoid reactions have also been reported in patients undergoing low-density lipoprotein apheresis with dextran sulfate absorption. Hepatic Failure : Rarely, ACE inhibitors have been associated with a syndrome that starts with cholestatic jaundice and progresses to fulminant hepatic necrosis and (sometimes) death. The mechanism of this syndrome is not understood. Patients receiving ACE inhibitors who develop jaundice or marked elevations of hepatic enzymes should discontinue the ACE inhibitor and receive appropriate medical follow-up. Hypotension : Excessive hypotension is rare in patients with uncomplicated hypertension treated with quinapril alone. Patients with heart failure given quinapril commonly have some reduction in blood pressure, but discontinuation of therapy because of continuing symptomatic hypotension usually is not necessary when dosing instructions are followed. Caution should be observed when initiating therapy in patients with heart failure (see DOSAGE AND ADMINISTRATION ). In controlled studies, syncope was observed in 0.4% of patients (N=3203); this incidence was similar to that observed for captopril (1%) and enalapril (0.8%). Patients at risk of excessive hypotension, sometimes associated with oliguria and/or progressive azotemia, and rarely with acute renal failure and/or death, include patients with the following conditions or characteristics: heart failure, hyponatremia, high dose diuretic therapy, recent intensive diuresis or increase in diuretic dose, renal dialysis, or severe volume and/or salt depletion of any etiology. It may be advisable to eliminate the diuretic (except in patients with heart failure), reduce the diuretic dose or cautiously increase salt intake (except in patients with heart failure) before initiating therapy with quinapril in patients at risk for excessive hypotension who are able to tolerate such adjustments. In patients at risk of excessive hypotension, therapy with quinapril should be started under close medical supervision. Such patients should be followed closely for the first two weeks of treatment and whenever the dose of quinapril and/or diuretic is increased. Similar considerations may apply to patients with ischemic heart or cerebrovascular disease in whom an excessive fall in blood pressure could result in a myocardial infarction or a cerebrovascular accident. If excessive hypotension occurs, the patient should be placed in the supine position and, if necessary, receive an intravenous infusion of normal saline. A transient hypotensive response is not a contraindication to further doses of quinapril, which usually can be given without difficulty once the blood pressure has stabilized. If symptomatic hypotension develops, a dose reduction or discontinuation of quinapril or concomitant diuretic may be necessary. Neutropenia/Agranulocytosis: Another ACE inhibitor, captopril, has been shown to cause agranulocytosis and bone marrow depression rarely in patients with uncomplicated hypertension, but more frequently in patients with renal impairment, especially if they also have a collagen vascular disease, such as systemic lupus erythematosus or scleroderma. Agranulocytosis did occur during quinapril treatment in one patient with a history of neutropenia during previous captopril therapy. Available data from clinical trials of quinapril are insufficient to show that, in patients without prior reactions to other ACE inhibitors, quinapril does not cause agranulocytosis at similar rates. As with other ACE inhibitors, periodic monitoring of white blood cell counts in patients with collagen vascular disease and/or renal disease should be considered. Fetal Toxicity Pregnancy Category D Use of drugs that act on the renin-angiotensin system during the second and third trimesters of pregnancy reduces fetal renal function and increases fetal and neonatal morbidity and death. Resulting oligohydramnios can be associated with fetal lung hypoplasia and skeletal deformations. Potential neonatal adverse effects include skull hypoplasia, anuria, hypotension, renal failure, and death. When pregnancy is detected, discontinue quinapril as soon as possible. These adverse outcomes are usually associated with use of these drugs in the second and third trimester of pregnancy. Most epidemiologic studies examining fetal abnormalities after exposure to antihypertensive use in the first trimester have not distinguished drugs affecting the renin-angiotensin system from other antihypertensive agents. Appropriate management of maternal hypertension during pregnancy is important to optimize outcomes for both mother and fetus. In the unusual case that there is no appropriate alternative to therapy with drugs affecting the renin-angiotensin sy

CONTRAINDICATIONS Quinapril and hydrochlorothiazide tablets are contraindicated in patients who are hypersensitive to quinapril or hydrochlorothiazide and in patients with a history of angioedema related to previous treatment with an ACE inhibitor. Quinapril and hydrochlorothiazide tablets are contraindicated in combination with a neprilysin inhibitor (e.g., sacubitril). Do not administer quinapril and hydrochlorothiazide tablets within 36 hours of switching to or from sacubitril/valsartan, a neprilysin inhibitor (see WARNINGS and PRECAUTIONS ). Because of the hydrochlorothiazide components, this product is contraindicated in patients with anuria or hypersensitivity to other sulfonamide-derived drugs. Do not co-administer quinapril and hydrochlorothiazide tablets with aliskiren: in patients with diabetes.

Drug Interactions Agents Increasing Serum Potassium Coadministration of quinapril and hydrochlorothiazide with other drugs that raise serum potassium levels may result in hyperkalemia. Monitor serum potassium in such patients. 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 quinapril and hydrochlorothiazide, a thiazide diuretic is coadministered with the ACE inhibitor. Quinapril and hydrochlorothiazide and lithium should be coadministered with caution, and frequent monitoring of serum lithium levels is recommended. Dual Blockade of the Renin-Angiotensin System (RAS) Dual blockade of the RAS with angiotensin receptor blockers, ACE inhibitors, or aliskiren is associated with increased risks of hypotension, hyperkalemia, and changes in renal function (including acute renal failure) compared to monotherapy. Most patients receiving the combination of two RAS inhibitors do not obtain any additional benefit compared to monotherapy. In general, avoid combined use of RAS inhibitors. Closely monitor blood pressure, renal function and electrolytes in patients on quinapril and hydrochlorothiazide and other agents that affect the RAS. Do not co-administer aliskiren with quinapril and hydrochlorothiazide in patients with diabetes. Avoid concomitant use of aliskiren with quinapril and hydrochlorothiazide in patients with renal impairment (GFR <60 mL/min/1.73 m 2 ). Tetracycline and Other Drugs That Interact with Magnesium Simultaneous administration of tetracycline with quinapril reduced the absorption of tetracycline by approximately 28% to 37%, possibly due to the high magnesium content in quinapril tablets. This interaction should be considered if coprescribing quinapril and tetracycline or other drugs that interact with magnesium. 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. Non-Steroidal Anti-Inflammatory Agents including Selective Cyclooxygenase-2 Inhibitors (COX-2 Inhibitors) In patients who are elderly, volume-depleted (including those on diuretic therapy), or with compromised renal function, co-administration of NSAIDs, including selective COX-2 inhibitors, with ACE inhibitors, including quinapril, may result in deterioration of renal function, including possible acute renal failure. These effects are usually reversible. Monitor renal function periodically in patients receiving quinapril and NSAID therapy. The antihypertensive effect of ACE inhibitors, including quinapril may be attenuated by NSAIDs. Agents that Inhibit mTOR or Other Drugs Known to Cause Angioedema: Patients taking concomitant mTOR inhibitor (e.g., temsirolimus) therapy or a neprilysin inhibitor may be at increased risk for angioedema . Other Agents Drug interaction studies of quinapril and other agents showed: Multiple dose therapy with propranolol or cimetidine has no effect on the pharmacokinetics of single doses of quinapril. The anticoagulant effect of a single dose of warfarin (measured by prothrombin time) was not significantly changed by quinapril coadministration twice daily. Digoxin: Thiazide-induced electrolyte disturbances, i.e. hypokalemia, hypomagnesemia, increase the risk of digoxin toxicity, which may lead to fatal arrhythmic events (See PRECAUTIONS ). No pharmacokinetic interaction was observed when single doses of quinapril and hydrochlorothiazide were administered concomitantly. When administered concurrently, the following drugs may interact with thiazide diuretics. Alcohol, Barbiturates, or Narcotics—potentiation of orthostatic hypotension may occur. Antidiabetic Drugs (oral hypoglycemic agents and insulin)—dosage adjustments of the antidiabetic drug may be required (See PRECAUTIONS ). Cholestyramine and Colestipol Resin—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. Corticosteroids, ACTH—intensified electrolyte depletion, particularly hypokalemia. Pressor Amines (e.g., norepinephrine)—possible decreased response to pressor amines, but not sufficient to preclude their therapeutic use. Skeletal Muscle Relaxants, Nondepolarizing (e.g., tubocurarine)—possible increased responsiveness to the muscle relaxant. Non-steroidal Anti-inflammatory Drugs—the diuretic, natriuretic, and antihypertensive effects of thiazide diuretics may be reduced by concurrent administration of nonsteroidal anti-inflammatory agents.

ADVERSE REACTIONS Quinapril and hydrochlorothiazide has been evaluated for safety in 1571 patients in controlled and uncontrolled studies. Of these, 498 were given quinapril plus hydrochlorothiazide for at least 1 year, with 153 patients extending combination therapy for over 2 years. In clinical trials with quinapril and hydrochlorothiazide, no adverse experience specific to the combination has been observed. Adverse experiences that have occurred have been limited to those that have been previously reported with quinapril or hydrochlorothiazide. Adverse experiences were usually mild and transient, and there was no relationship between side effects and age, sex, race, or duration of therapy. Discontinuation of therapy because of adverse effects was required in 2.1% in patients in controlled studies. The most common reasons for discontinuation of therapy with quinapril and hydrochlorothiazide were cough (1%; see PRECAUTIONS ) and headache (0.7%). Adverse experiences probably or possibly related to therapy or of unknown relationship to therapy occurring in 1% or more of the 943 patients treated with quinapril plus hydrochlorothiazide in controlled trials are shown below. Percent of Patients in Controlled Trials Quinapril/HCTZ N = 943 Placebo N = 100 Headache 6.7 30 Dizziness 4.8 4 Coughing 3.2 2 Fatigue 2.9 3 Myalgia 2.4 5 Viral Infection 1.9 4 Rhinitis 2 3 Nausea and/or Vomiting 1.8 6 Abdominal Pain 1.7 4 Back Pain 1.5 2 Diarrhea 1.4 1 Upper Respiratory Infection 1.3 4 Insomnia 1.2 2 Somnolence 1.2 0 Bronchitis 1.2 1 Dyspepsia 1.2 2 Asthenia 1.1 1 Pharyngitis 1.1 2 Vasodilatation 1 1 Vertigo 1 2 Chest Pain 1 2 Clinical adverse experiences probably, possibly, or definitely related or of uncertain relationship to therapy occurring in ≥0.5% to <1% (except as noted) of the patients treated with quinapril/HCTZ in controlled and uncontrolled trials (N=1571) and less frequent, clinically significant events seen in clinical trials or postmarketing experience (the rarer events are in italics) include (listed by body system): BODY AS A WHOLE: Asthenia, Malaise CARDIOVASCULAR: Palpitation, Tachycardia, Heart Failure, Hyperkalemia, Myocardial Infarction, Cerebrovascular Accident, Hypertensive Crisis, Angina Pectoris, Orthostatic Hypotension, Cardiac Rhythm Disturbance GASTROINTESTINAL: Mouth or Throat Dry, Gastrointestinal Hemorrhage, Pancreatitis, Abnormal Liver Function Tests NERVOUS/PSYCHIATRIC: Nervousness, Vertigo, Paresthesia RESPIRATORY: Sinusitis, Dyspnea INTEGUMENTARY: Pruritus, Sweating Increased, Erythema Multiforme, Exfoliative Dermatitis, Photosensitivity Reaction, Alopecia, Pemphigus UROGENITAL SYSTEM: OTHER: Acute Renal Failure, Impotence Agranulocytosis, Thrombocytopenia, Arthralgia Angioedema: Angioedema has been reported in 0.1% of patients receiving quinapril (0.1%) (see WARNINGS ). Postmarketing Experience The following serious nonfatal adverse events, regardless of their relationship to quinapril and HCTZ combination tablets, have been reported during extensive postmarketing experience: Non-melanoma Skin Cancer: Hydrochlorothiazide is associated with an increased risk of non-melanoma skin cancer. In a study conducted in the Sentinel System, increased risk was predominantly for squamous cell carcinoma (SCC) and in white patients taking large cumulative doses. The increased risk for SCC in the overall population was approximately 1 additional case per 16,000 patients per year, and for white patients taking a cumulative dose of ≥50,000 mg the risk increase was approximately 1 additional SCC case for every 6,700 patients per year. BODY AS A WHOLE: Shock, accidental injury, neoplasm, cellulitis, ascites, generalized edema, hernia and anaphylactoid reaction. CARDIOVASCULAR SYSTEM: Bradycardia, cor pulmonale, vasculitis, and deep vein thrombosis. DIGESTIVE SYSTEM: Gastrointestinal carcinoma, cholestatic jaundice, hepatitis, esophagitis, vomiting, and diarrhea. EYE DISORDERS: Acute myopia and acute angle closure glaucoma (see WARNINGS ). HEMIC SYSTEM: Anemia. METABOLIC AND NUTRITIONAL DISORDERS: Weight loss. MUSCULOSKELETAL SYSTEM: Myopathy, myositis, and arthritis. NERVOUS SYSTEM: Paralysis, hemiplegia, speech disorder, abnormal gait, meningism, and amnesia. RESPIRATORY SYSTEM: Pneumonia, asthma, respiratory infiltration, and lung disorder. SKIN AND APPENDAGES: Urticaria, macropapular rash, and petechiases. SPECIAL SENSES: Abnormal vision. UROGENITAL SYSTEM: Kidney function abnormal, albuminuria, pyuria, hematuria, and nephrosis. Quinapril monotherapy has been evaluated for safety in 4960 patients. In clinical trials adverse events which occurred with quinapril were also seen with quinapril and hydrochlorothiazide. In addition, the following were reported for quinapril at an incidence >0.5%: depression, back pain, constipation, syncope, and amblyopia. Hydrochlorothiazide has been extensively prescribed for many years, but there has not been enough systematic collection of data to support an estimate of the frequency of the observed adverse reactions. Within organ-system groups, the reported reactions are listed here in decreasing order of severity, without regard to frequency. BODY AS A WHOLE: Weakness. CARDIOVASCULAR: Orthostatic hypotension (may be potentiated by alcohol, barbiturates, or narcotics). DIGESTIVE: Pancreatitis, jaundice (intrahepatic cholestatic), sialadenitis, vomiting, diarrhea, cramping, nausea, gastric irritation, constipation, and anorexia. NEUROLOGIC: Vertigo, lightheadedness, transient blurred vision, headache, paresthesia, xanthopsia, weakness, and restlessness. MUSCULOSKELETAL: Muscle spasm. HEMATOLOGIC: Aplastic anemia, agranulocytosis, leukopenia, thrombocytopenia, and hemolytic anemia. RENAL: Renal failure, renal dysfunction, interstitial nephritis (see WARNINGS ). METABOLIC: Hyperglycemia, glycosuria, and hyperuricemia. HYPERSENSITIVITY: Necrotizing angiitis, Stevens-Johnson syndrome, respiratory distress (including pneumonitis and pulmonary edema), purpura, urticaria, rash, and photosensitivity. Clinical Laboratory Test Findings Serum Electrolytes: See PRECAUTIONS . Creatinine, Blood Urea Nitrogen Increases (>1.25 times the upper limit of normal) in serum creatinine and blood urea nitrogen were observed in 3% and 4%, respectively, of patients treated with quinapril and hydrochlorothiazide. Most increases were minor and reversible, which can occur in patients with essential hypertension but most frequently in patients with renal artery stenosis (see PRECAUTIONS ). PBI and Tests of Parathyroid Function: See PRECAUTIONS . Hematology: See WARNINGS . Other (causal relationships unknown) Other clinically important changes in standard laboratory tests were rarely associated with quinapril and hydrochlorothiazide administration. Elevations in uric acid, glucose, magnesium, cholesterol, triglyceride, and calcium (see PRECAUTIONS ) have been reported.

CLINICAL PHARMACOLOGY Mechanism of Action The principal metabolite of quinapril, quinaprilat, is an inhibitor of ACE activity in human subjects and animals. ACE is peptidyl dipeptidase that catalyzes the conversion of angiotensin I to the vasoconstrictor, angiotensin II. The effect of quinapril in hypertension appears to result primarily from the inhibition of circulating and tissue ACE activity, thereby reducing angiotensin II formation. Quinapril inhibits the elevation in blood pressure caused by intravenously administered angiotensin I, but has no effect on the pressor response to angiotensin II, norepinephrine, or epinephrine. Angiotensin II also stimulates the secretion of aldosterone from the adrenal cortex, thereby facilitating renal sodium and fluid reabsorption. Reduced aldosterone secretion by quinapril may result in a small increase in serum potassium. In controlled hypertension trials, treatment with quinapril alone resulted in mean increases in potassium of 0.07 mmol/L (see PRECAUTIONS ). Removal of angiotensin II negative feedback on renin secretion leads to increased plasma renin activity (PRA). While the principal mechanism of antihypertensive effect is thought to be through the renin-angiotensin-aldosterone system, quinapril exerts antihypertensive actions even in patients with low renin hypertension. Quinapril was an effective antihypertensive in all races studied, although it was somewhat less effective in blacks (usually a predominantly low renin group) than in non-blacks. ACE is identical to kininase II, an enzyme that degrades bradykinin, a potent peptide vasodilator; whether increased levels of bradykinin play a role in the therapeutic effect of quinapril remains to be elucidated. Hydrochlorothiazide is a thiazide diuretic. Thiazides affect the renal tubular mechanisms of electrolyte reabsorption, directly increasing excretion of sodium and chloride in approximately equivalent amounts. Indirectly, the diuretic action of hydrochlorothiazide reduces plasma volume, with consequent increases in plasma renin activity, increases in aldosterone secretion, increases in urinary potassium loss, and decreases in serum potassium. The renin-aldolsterone link is mediated by angiotensin, so coadministration of an ACE inhibitor tends to reverse the potassium loss associated with these diuretics. The mechanism of the antihypertensive effect of thiazides is unknown. Pharmacokinetics and Metabolism The rate and extent of absorption of quinapril and hydrochlorothiazide from quinapril and hydrochlorothiazide tablets are not different, respectively, from the rate and extent of absorption of quinapril and hydrochlorothiazide from immediate-release monotherapy formulations, either administered concurrently or separately. Following oral administration of quinapril monotherapy tablets, peak plasma quinapril concentrations are observed within 1 hour. Based on recovery of quinapril and its metabolites in urine, the extent of absorption is at least 60%. The absorption of hydrochlorothiazide is somewhat slower (1 to 2.5 hours) and more complete (50% to 80%). The rate of quinapril absorption was reduced by 14% when quinapril and hydrochlorothiazide tablets were administered with a high-fat meal as compared to fasting, while the extent of absorption was not affected. The rate of hydrochlorothiazide absorption was reduced by 12% when quinapril and hydrochlorothiazide tablets were administered with a high-fat meal, while the extent of absorption was not significantly affected. Therefore, quinapril and hydrochlorothiazide may be administered without regard to food. Following absorption, quinapril is deesterified to its major active metabolite, quinaprilat (about 38% of oral dose), and to other minor inactive metabolites. Following multiple oral dosing of quinapril, there is an effective accumulation half-life of quinaprilat of approximately 3 hours, and peak plasma quinaprilat concentrations are observed approximately 2 hours postdose. Approximately 97% of either quinapril or quinaprilat circulating in plasma is bound to proteins. Hydrochlorothiazide is not metabolized. Its apparent volume of distribution is 3.6 to 7.8 L/kg, consistent with measured plasma protein binding of 67.9%. The drug also accumulates in red blood cells, so that whole blood levels are 1.6 to 1.8 times those measured in plasma. Some placental passage occurred when quinapril was administered to pregnant rats. Studies in rats indicate that quinapril and its metabolites do not cross the blood-brain barrier. Hydrochlorothiazide crosses the placenta freely but not the blood-brain barrier. Quinaprilat is eliminated primarily by renal excretion, up to 96% of an IV dose, and has an elimination half-life in plasma of approximately 2 hours and a prolonged terminal phase with a half-life of 25 hours. Hydrochlorothiazide is excreted unchanged by the kidney. When plasma levels have been followed for at least 24 hours, the plasma half-life has been observed to vary between 4 to 15 hours. At least 61% of the oral dose is eliminated unchanged within 24 hours. In patients with renal insufficiency, the elimination half-life of quinaprilat increases as creatinine clearance decreases. There is a linear correlation between plasma quinaprilat clearance and creatinine clearance. In patients with end-stage renal disease, chronic hemodialysis or continuous ambulatory peritoneal dialysis have little effect on the elimination of quinapril and quinaprilat. Elimination of quinaprilat is reduced in elderly patients (≥65 years) and in those with heart failure; this reduction is attributable to decrease in renal function (see DOSAGE AND ADMINISTRATION ). Quinaprilat concentrations are reduced in patients with alcoholic cirrhosis due to impaired deesterification of quinapril. In a study of patients with impaired renal function (mean creatinine clearance of 19 mL/min), the half-life of hydrochlorothiazide elimination was lengthened to 21 hours. The pharmacokinetics of quinapril and quinaprilat are linear over a single-dose range of 5 to 80 mg doses and 40 to 160 mg in multiple daily doses. Pharmacodynamics and Clinical Effects Single doses of 20 mg of quinapril provide over 80% inhibition of plasma ACE for 24 hours. Inhibition of the pressor response to angiotensin I is shorter-lived, with a 20 mg dose giving 75% inhibition for about 4 hours, 50% inhibition for about 8 hours, and 20% inhibition at 24 hours. With chronic dosing, however, there is substantial inhibition of angiotensin II levels at 24 hours by doses of 20 to 80 mg. Administration of 10 to 80 mg of quinapril to patients with mild to severe hypertension results in a reduction of sitting and standing blood pressure to about the same extent with minimal effect on heart rate. Symptomatic postural hypotension is infrequent, although it can occur in patients who are salt- and/or volume-depleted (see WARNINGS ). Antihypertensive activity commences within 1 hour with peak effects usually achieved by 2 to 4 hours after dosing. During chronic therapy, most of the blood pressure lowering effect of a given dose is obtained in 1 to 2 weeks. In multiple-dose studies, 10 to 80 mg per day in single or divided doses lowered systolic and diastolic blood pressure throughout the dosing interval, with a trough effect of about 5 to 11/3 to 7 mm Hg. The trough effect represents about 50% of the peak effect. While the dose-response relationship is relatively flat, doses of 40 to 80 mg were somewhat more effective at trough than 10 to 20 mg, and twice-daily dosing tended to give a somewhat lower trough blood pressure than once-daily dosing with the same total dose. The antihypertensive effect of quinapril continues during long-term therapy, with no evidence of loss of effectiveness. Hemodynamic assessments in patients with hypertension indicate that blood pressure reduction produced by quinapril is accompanied by a reduction in total peripheral resistance and renal vascular resistanc