Lisinopril (Page 6 of 8)

12.2 Pharmacodynamics

Hypertension

Adult Patients

Administration of lisinopril tablets to patients with hypertension results in a reduction of both supine and standing blood pressure to about the same extent with no compensatory tachycardia. Symptomatic postural hypotension is usually not observed although it can occur and should be anticipated in volume and/or salt-depleted patients [see Warnings and Precautions (5.4)] . When given together with thiazide-type diuretics, the blood pressure lowering effects of the two drugs are approximately additive.

In most patients studied, onset of antihypertensive activity was seen at 1 hour after oral administration of an individual dose of lisinopril tablets, with peak reduction of blood pressure achieved by 6 hours. Although an antihypertensive effect was observed 24 hours after dosing with recommended single daily doses, the effect was more consistent and the mean effect was considerably larger in some studies with doses of 20 mg or more than with lower doses; however, at all doses studied, the mean antihypertensive effect was substantially smaller 24 hours after dosing than it was 6 hours after dosing.

The antihypertensive effects of lisinopril tablets are maintained during long-term therapy. Abrupt withdrawal of lisinopril tablets has not been associated with a rapid increase in blood pressure, or a significant increase in blood pressure compared to pretreatment levels.

Non-Steroidal Anti-Inflammatory Agents

In a study in 36 patients with mild to moderate hypertension where the antihypertensive effects of lisinopril tablets alone were compared to lisinopril tablets given concomitantly with indomethacin, the use of indomethacin was associated with a reduced effect, although the difference between the two regimens was not significant.

12.3 Pharmacokinetics

Adult Patients

Following oral administration of lisinopril tablets, peak serum concentrations of lisinopril occur within about 7 hours, although there was a trend to a small delay in time taken to reach peak serum concentrations in acute myocardial infarction patients. Food does not alter the bioavailability of lisinopril tablets. Declining serum concentrations exhibit a prolonged terminal phase, which does not contribute to drug accumulation. This terminal phase probably represents saturable binding to ACE and is not proportional to dose. Upon multiple dosing, lisinopril exhibits an effective half-life of 12 hours.

Lisinopril does not appear to be bound to other serum proteins. Lisinopril does not undergo metabolism and is excreted unchanged entirely in the urine. Based on urinary recovery, the mean extent of absorption of lisinopril is approximately 25%, with large intersubject variability (6% to 60%) at all doses tested (5 mg to 80 mg). The absolute bioavailability of lisinopril is reduced to 16% in patients with stable NYHA Class II-IV congestive heart failure, and the volume of distribution appears to be slightly smaller than that in normal subjects. The oral bioavailability of lisinopril in patients with acute myocardial infarction is similar to that in healthy volunteers.

Impaired renal function decreases elimination of lisinopril, which is excreted principally through the kidneys, but this decrease becomes clinically important only when the glomerular filtration rate is below 30 mL/min. Above this glomerular filtration rate, the elimination half-life is little changed. With greater impairment, however, peak and trough lisinopril levels increase, time to peak concentration increases and time to attain steady state is prolonged [see Dosage and Administration (2.4)] . Lisinopril can be removed by hemodialysis.

Pediatric Patients

The pharmacokinetics of lisinopril were studied in 29 pediatric hypertensive patients between 6 years and 16 years with glomerular filtration rate > 30 mL/min/1.73 m 2. After doses of 0.1 mg to 0.2 mg per kg, steady state peak plasma concentrations of lisinopril occurred within 6 hours and the extent of absorption based on urinary recovery was about 28%. These values are similar to those obtained previously in adults. The typical value of lisinopril oral clearance (systemic clearance/absolute bioavailability) in a child weighing 30 kg is 10 L/h, which increases in proportion to renal function. In a multicenter, open-label pharmacokinetic study of daily oral lisinopril in 22 pediatric hypertensive patients with stable kidney transplant (ages 7 to 17 years; estimated glomerular filtration rate > 30 mL/min/1.73 m 2), dose normalized exposures were in the range reported previously in children without a kidney transplant.

13 NONCLINICAL TOXICOLOGY

13.1 Carcinogenesis, Mutagenesis, Impairment of Fertility

There was no evidence of a tumorigenic effect when lisinopril was administered for 105 weeks to male and female rats at doses up to 90 mg per kg per day (about 56 or 9 times* the maximum recommended daily human dose, based on body weight and body surface area, respectively). There was no evidence of carcinogenicity when lisinopril was administered for 92 weeks to (male and female) mice at doses up to 135 mg per kg per day (about 84 times* the maximum recommended daily human dose). This dose was 6.8 times the maximum human dose based on body surface area in mice.

Lisinopril was not mutagenic in the Ames microbial mutagen test with or without metabolic activation. It was also negative in a forward mutation assay using Chinese hamster lung cells. Lisinopril did not produce single strand DNA breaks in an in vitro alkaline elution rat hepatocyte assay. In addition, lisinopril did not produce increases in chromosomal aberrations in an in vitro test in Chinese hamster ovary cells or in an in vivo study in mouse bone marrow.

There were no adverse effects on reproductive performance in male and female rats treated with up to 300 mg per kg per day of lisinopril. This dose is 188 times and 30 times the maximum human dose when based on mg/kg and mg/m 2 , respectively.

Studies in rats indicate that lisinopril crosses the blood brain barrier poorly. Multiple doses of lisinopril in rats do not result in accumulation in any tissues. Milk of lactating rats contains radioactivity following administration of 14 C lisinopril. By whole body autoradiography, radioactivity was found in the placenta following administration of labeled drug to pregnant rats, but none was found in the fetuses.

*Calculations assume a human weight of 50 kg and human body surface area of 1.62 m 2.

14 CLINICAL STUDIES

14.1 Hypertension

Two dose-response studies utilizing a once-daily regimen were conducted in 438 mild to moderate hypertensive patients not on a diuretic. Blood pressure was measured 24 hours after dosing. An antihypertensive effect of lisinopril tablets was seen with 5 mg of lisinopril in some patients. However, in both studies blood pressure reduction occurred sooner and was greater in patients treated with 10 mg, 20 mg or 80 mg of lisinopril than patients treated with 5 mg of lisinopril.

In controlled clinical studies of patients with mild to moderate hypertension, patients were treated with lisinopril 20 mg to 80 mg daily, hydrochlorothiazide 12.5 mg to 50 mg daily or atenolol 50 mg to 200 mg daily; and in other studies of patients with moderate to severe hypertension, patients were treated with lisinopril 20 mg to 80 mg daily or metoprolol 100 mg to 200 mg daily. Lisinopril demonstrated superior reductions of systolic and diastolic compared to hydrochlorothiazide in a population that was 75% Caucasian. Lisinopril was approximately equivalent to atenolol and metoprolol in reducing diastolic blood pressure, and had somewhat greater effects on systolic blood pressure.

Lisinopril tablets had similar blood pressure reductions and adverse effects in younger and older (> 65 years) patients. It was less effective in reducing blood pressure in Blacks than in Caucasians.

In hemodynamic studies of lisinopril tablets in patients with essential hypertension, blood pressure reduction was accompanied by a reduction in peripheral arterial resistance with little or no change in cardiac output and in heart rate. In a study in nine hypertensive patients, following administration of lisinopril tablets, there was an increase in mean renal blood flow that was not significant. Data from several small studies are inconsistent with respect to the effect of lisinopril on glomerular filtration rate in hypertensive patients with normal renal function, but suggest that changes, if any, are not large.

In patients with renovascular hypertension, lisinopril tablets have been shown to be well tolerated and effective in reducing blood pressure [see Warnings and Precautions (5.3)] .

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