QUINAPRIL TABLETS, USP
5 mg, 10 mg, 20 mg and 40 mg

When used in pregnancy during the second and third trimesters, ACE inhibitors can cause injury and even death to the developing fetus. When pregnancy is detected, quinapril should be discontinued as soon as possible. See WARNINGS: Fetal/Neonatal Morbidity and Mortality.

Quinapril hydrochloride is the hydrochloride salt of quinapril, the ethyl ester of a nonsulfhydryl, angiotensin-converting enzyme (ACE) inhibitor, quinaprilat.

Quinapril hydrochloride is chemically described as [3S-[2[R^*(R^*)], 3R^*]]-2-[2-[[1-(ethoxycarbonyl)-3-phenylpropyl]amino]-1-oxopropyl]-1,2,3,4- tetrahydro-3-isoquinoline-carboxylic acid, monohydrochloride. Its molecular formula is C₂₅H₃₀N₂O₅• HCl and its structural formula is:

Quinapril hydrochloride is a white to off-white amorphous powder that is freely soluble in aqueous solvents.

Quinapril tablets, USP contain 5 mg, 10 mg, 20 mg, or 40 mg of quinapril for oral administration. Each tablet also contains the following inactive ingredients: colloidal silicon dioxide, crospovidone, D&C Yellow #6 FCF Lake, hypromellose, magnesium carbonate, magnesium stearate, microcrystalline cellulose, povidone, polydextrose, polyethylene glycol, sodium lauryl sulfate and triacetin.

Quinapril is deesterified to the principal metabolite, quinaprilat, which is an inhibitor of ACE activity in human subjects and animals. ACE is a 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.

Following oral administration, peak plasma quinapril concentrations are observed within one hour. Based on recovery of quinapril and its metabolites in urine, the extent of absorption is at least 60%. The rate and extent of quinapril absorption are diminished moderately (approximately 25 to 30%) when quinapril hydrochloride tablets are administered during a high-fat meal. 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 post-dose. 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. 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. Approximately 97% of either quinapril or quinaprilat circulating in plasma is bound to proteins.

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 has little effect on the elimination of quinapril and quinaprilat. Elimination of quinaprilat may be 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. Studies in rats indicate that quinapril and its metabolites do not cross the blood-brain barrier.

Quinapril hydrochloride tablets are indicated for the treatment of hypertension. They may be used alone or in combination with thiazide diuretics.

In using quinapril hydrochloride tablets, consideration should be given to the fact that another angiotensin-converting enzyme inhibitor, captopril, has caused agranulocytosis, particularly in patients with renal impairment or collagen vascular disease. Available data are insufficient to show that quinapril hydrochloride tablets do not have a similar risk (see WARNINGS).

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.

Quinapril hydrochloride tablets are contraindicated in patients who are hypersensitive to this product and in patients with a history of angioedema related to previous treatment with an ACE inhibitor.

Presumably because angiotensin-converting 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.

Quinapril hydrochloride was not carcinogenic in mice or rats when given in doses up to 75 or 100 mg/kg/day (50 to 60 times the maximum human daily dose, respectively, on an mg/kg basis and 3.8 to 10 times the maximum human daily dose when based on an mg/m² basis) for 104 weeks. Female rats given the highest dose level had an increased incidence of mesenteric lymph node hemangiomas and skin/subcutaneous lipomas. Neither quinapril nor quinaprilat were mutagenic in the Ames bacterial assay with or without metabolic activation. Quinapril was also negative in the following genetic toxicology studies: in vitro mammalian cell point mutation, sister chromatid exchange in cultured mammalian cells, micronucleus test with mice, in vitro chromosome aberration with V79 cultured lung cells, and in an in vivo cytogenetic study with rat bone marrow. There were no adverse effects on fertility or reproduction in rats at doses up to 100 mg/kg/day (60 and 10 times the maximum daily human dose when based on mg/kg and mg/m², respectively).

Because quinapril is secreted in human milk, caution should be exercised when this drug is administered to a nursing woman.

The safety and effectiveness of quinapril in pediatric patients have not been established.

Clinical studies of quinapril 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 the 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.

This drug is known to be substantially excreted by the kidney, and the risk of toxic reactions to this drug may be greater in patients with impaired renal function. Because elderly patients are more likely to have decreased renal function, care should be taken in dose selection, and it may be useful to monitor renal function.

Elderly patients exhibited increased area under the plasma concentration time curve and peak levels for quinaprilat compared to values observed in younger patients; this appeared to relate to decreased renal function rather than to age itself.

Quinapril has been evaluated for safety in 4960 subjects and patients. Of these, 3203 patients, including 655 elderly patients, participated in controlled clinical trials. Quinapril has been evaluated for long-term safety in over 1400 patients treated for 1 year or more.

Adverse experiences were usually mild and transient.

In placebo-controlled trials, discontinuation of therapy because of adverse events was required in 4.7% of patients with hypertension.

Adverse experiences probably or possibly related to therapy or of unknown relationship to therapy occurring in 1% or more of the 1563 patients in placebo-controlled hypertension trials who were treated with quinapril are shown below.

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 with hypertension treated with quinapril (with or without concomitant diuretic) in controlled or uncontrolled trials (N = 4847) and less frequent, clinically significant events seen in clinical trials or postmarketing experience (the rarer events are in italics) include (uled by body system):

General: back pain, malaise, viral infections, anaphylactoid reaction

Cardiovascular: palpitation, vasodilation, tachycardia, heart failure, hyperkalemia, myocardial infarction, cerebrovascular accident, hypertensive crisis, angina pectoris, orthostatic hypotension, cardiac rhythm disturbances, cardiogenic shock

Hematology: hemolytic anemia

Gastrointestinal: flatulence, dry mouth or throat, constipation, gastrointestinal hemorrhage, pancreatitis, abnormal liver function tests, dyspepsia

Nervous/Psychiatric: somnolence, vertigo, syncope, nervousness, depression, insomnia, paresthesia

Integumentary: alopecia, increased sweating, pemphigus, pruritus, exfoliative dermatitis, photosensitivity reaction, dermatopolymyositis

Urogenital: urinary tract infection, impotence, acute renal failure, worsening renal failure

Respiratory: eosinophilic pneumonitis

Other: amblyopia, edema, arthralgia, pharyngitis, agranulocytosis, hepatitis, thrombocytopenia

See WARNINGS: Fetal/Neonatal Morbidity and Mortality.

Angioedema has been reported in patients receiving quinapril (0.1%). Angioedema associated with laryngeal edema may be fatal. If angioedema of the face, extremities, lips, tongue, glottis, and/or larynx occurs, treatment with quinapril should be discontinued and appropriate therapy instituted immediately. (See WARNINGS.)

Hematology: (See WARNINGS.)

Hyperkalemia: (See PRECAUTIONS.)

Creatinine and Blood Urea Nitrogen: Increases (> 1.25 times the upper limit of normal) in serum creatinine and blood urea nitrogen were observed in 2% and 2%, respectively, of all patients treated with quinapril alone. Increases are more likely to occur in patients receiving concomitant diuretic therapy than in those on quinapril alone. These increases often remit on continued therapy.

Doses of 1440 to 4280 mg/kg of quinapril cause significant lethality in mice and rats.

No specific information is available on the treatment of overdosage with quinapril. The most likely clinical manifestation would be symptoms attributable to severe hypotension.

Laboratory determinations of serum levels of quinapril and its metabolites are not widely available, and such determinations have, in any event, no established role in the management of quinapril overdose.

No data are available to suggest physiological maneuvers (e.g., maneuvers to change pH of the urine) that might accelerate elimination of quinapril and its metabolites.

Hemodialysis and peritoneal dialysis have little effect on the elimination of quinapril and quinaprilat. Angiotensin II could presumably serve as a specific antagonist-antidote in the setting of quinapril overdose, but angiotensin II is essentially unavailable outside of scattered research facilities. Because the hypotensive effect of quinapril is achieved through vasodilation and effective hypovolemia, it is reasonable to treat quinapril overdose by infusion of normal saline solution.

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 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 WARNINGS and PRECAUTIONS: Drug Interactions.)

If the initial dose is well tolerated, quinapril 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.

Quinapril tablets, USP are available containing 5 mg, 10 mg, 20 mg or 40 mg of quinapril.

The 5 mg tablets are orange film-coated, round, biconvex, beveled edge, scored tablets debossed with M on one side of the tablet and 1 to the left of the score and 7 to the right of the score on the other side. They are available as follows:

NDC 0378-0117-77
bottles of 90 tablets

NDC 0378-0117-05
bottles of 500 tablets

The 10 mg tablets are orange film-coated, round, biconvex, beveled edge, unscored tablets debossed with M on one side of the tablet and 226 on the other side. They are available as follows:

NDC 0378-0226-77
bottles of 90 tablets

NDC 0378-0226-05
bottles of 500 tablets

The 20 mg tablets are orange film-coated, round, biconvex, beveled edge, unscored tablets debossed with M on one side of the tablet and 254 on the other side. They are available as follows:

NDC 0378-0254-77
bottles of 90 tablets

NDC 0378-0254-05
bottles of 500 tablets

The 40 mg tablets are orange film-coated, round, biconvex, beveled edge, unscored tablets debossed with M on one side of the tablet and 272 on the other side. They are available as follows:

NDC 0378-0272-77
bottles of 90 tablets