Richard A. Reeves

Apixaban, an oral, direct factor Xa inhibitor: single dose safety, pharmacokinetics, pharmacodynamics and food effect in healthy subjects

To evaluate apixaban single dose safety, tolerability, pharmacokinetics and pharmacodynamics and assess the effect of food on apixaban pharmacokinetics.

Matrix study of irbesartan with hydrochlorothiazide in mild-to-moderate hypertension

The purpose of this study was to assess the safety and antihypertensive dose-response effects of irbesartan and hydrochlorothiazide (HCTZ) in patients with mild-to-moderate hypertension. After a 4- to 5-week single-blind placebo lead-in period, 683 patients with seated diastolic blood pressure (SeDBP) between 95 and 110 mm Hg were randomized to receive once-daily dosing with one of 16 different double-blind, fixed combinations of irbesartan (0, 37.5, 100, and 300 mg irbesartan) and HCTZ (0, 6.25, 12.5, and 25 mg HCTZ) for 8 weeks. The primary efficacy variable was the change from baseline in trough SeDBP after 8 weeks of therapy. Data were analyzed by response surface modeling. At Week 8, mean changes from baseline in trough SeDBP (mm Hg) ranged from -3.5 for placebo, -7.1 to -10.2 for the irbesartan monotherapy groups, -5.1 to -8.3 for the HCTZ monotherapy groups, and -8.1 to -15.0 for the combination groups. Irbesartan plus HCTZ produced additive reductions in both SeDBP and seated systolic BP, with at least one combination producing greater BP reduction than either drug alone (P < .001). All treatments were well tolerated; there were no treatment-related serious adverse events. Irbesartan tended to ameliorate the dose-related biochemical abnormalities associated with HCTZ alone. In conclusion, the combination of HCTZ in doses up to 25 mg with irbesartan, in doses up to 300 mg, is safe and produces dose-dependent reductions in BP.

Dose-Related Antihypertensive Effects of Irbesartan in Patients With Mild-to-Moderate Hypertension

Two multicenter, double-blind, placebo-controlled, parallel group studies were conducted to evaluate the efficacy, safety, pharmacokinetics, and pharmacodynamics of the angiotensin II receptor (AT1 subtype) antagonist irbesartan. The effect of irbesartan withdrawal and the effect of adding hydrochlorothiazide (HCTZ) to irbesartan were also assessed. After a placebo lead-in phase, all patients were randomized to 8 weeks of double-blind therapy with either placebo (n = 158) or irbesartan at doses of 1, 5, 10, 25, 50, 100, 200, or 300 mg (n = 731 total) orally once daily. Irbesartan reduced blood pressure in a dose-related manner. Reductions from baseline in trough seated diastolic blood pressure ranged from 7.5 mm Hg for 50 mg irbesartan to 11.6 mm Hg for 300 mg irbesartan. At week 8, statistically significant reductions over placebo were observed in trough seated blood pressure with all irbesartan doses > or = 50 mg. These reductions reached statistical significance versus placebo within 2 weeks with 100, 200, and 300 mg irbesartan. Plasma irbesartan concentrations correlated with dose. Angiotensin II and aldosterone levels generally showed dose-related changes, consistent with AT1 receptor blockade. In patients not controlled at 8 weeks, the addition of 12.5 mg HCTZ resulted in further dose-related reductions in blood pressure. Irbesartan demonstrated a placebo-like safety profile and no dose-related toxicity. Irbesartan, administered alone or in combination with HCTZ, was well tolerated. Withdrawal of irbesartan did not result in rebound hypertension or adverse events. Thus, once-daily irbesartan is both an effective and safe antihypertensive agent for the treatment of mild-to-moderate hypertension.

Dose-Related Efficacy of Irbesartan for Hypertension An Integrated Analysis

Results of eight multicenter, randomized, placebo-controlled, double-blind, parallel-group studies were pooled to assess the efficacy of the angiotensin II-receptor blocker irbesartan over the dose range of 1 to 900 mg. A total of 2955 adults with a seated diastolic blood pressure of 95 to 110 mm Hg were randomized to treatment with oral irbesartan once daily or placebo for 6 to 8 weeks. Office blood pressure was measured at trough (24+/-3 hours after the last dose) and peak (3+/-1 hours after the last dose) by mercury sphygmomanometry. Demographic characteristics (mean blood pressure; 151/101 mm Hg; mean age, 54 years; 63% male; and 82% white) were similar across all dose groups. After the groups were pooled, antihypertensive efficacy was assessed by therapeutic response (trough seated diastolic blood pressure <90 mm Hg or a reduction from baseline of > or = 10 mm Hg) and by modeling of the maximum reductions in trough and peak seated diastolic and systolic blood pressure. Antihypertensive effects increased with increasing doses and reached a plateau at > or = 300 mg. Irbesartan 150 mg provided placebo-subtracted reductions in trough seated systolic and diastolic blood pressure of approximately 8 and approximately 5 mm Hg, respectively, with 56% of patients displaying a favorable response. In conclusion, irbesartan provides clinically significant blood pressure lowering, with a clear relationship between (log) dose and antihypertensive effect.

Effects and Tolerability of Irbesartan Versus Enalapril in Patients With Severe Hypertension fn1

: In this double-blind, randomized study, an antihypertensive regimen based on irbesartan, an angiotensin II receptor antagonist, reduced systolic and diastolic blood pressure by 40/30 mm Hg at week 12 in patients with severe hypertension; this reduction was at least equivalent to that of a regimen using enalapril up to 40 mg. The irbesartan-based regimen had a better tolerability profile with fewer adverse events (55% vs 64%) and significantly less cough (2.5% vs 13.1%, p = 0.007).

Pharmacokinetics and Tolerability of Intramuscular, Oral and Intravenous Aripiprazole in Healthy Subjects and in Patients with Schizophrenia

AbstractBackground and objective: Patients with schizophrenia or bipolar disorder who are experiencing acute behavioural emergencies often require intramuscular injection of antipsychotics for rapid symptom resolution. The efficacy and tolerability of intramuscular aripiprazole injection has been established in agitated inpatients with schizophrenia or bipolar I disorder. The main objective of the two clinical pharmacology studies reported here was to evaluate the pharmacokinetics of aripiprazole after intramuscular dosing in healthy subjects and in patients with schizophrenia, and after intravenous and oral dosing in healthy subjects. Subjects and methods: Study 1 was an open-label, randomized, three-treatment crossover study in healthy subjects (n= 18) to assess the bioavailability and pharmacokinetics of intramuscular aripiprazole 5 mg and oral aripiprazole 5 mg relative to intravenous aripiprazole 2 mg. Study 2 was an open-label, nonrandomized, escalating-dose study in patients with schizophrenia (n = 32) to evaluate the pharmacokinetics of intramuscular aripiprazole across a range of doses (from 1 mg to 45 mg). Main outcome measures: The noncompartmental pharmacokinetic parameters for plasma concentrations of aripiprazole and its active metabolite dehydro-aripiprazole were determined. Safety and tolerability data are also summarized. Results: In study 1, the geometric mean values for the absolute bioavailability of aripiprazole following oral and intramuscular administration were 0.85 and 0.98, respectively. Intramuscular aripiprazole demonstrated more rapid attainment of plasma aripiprazole concentrations than oral aripiprazole (78% and 5% of peak plasma concentration [Cmax] values at 0.5 hours postdose, respectively). The area under the plasma concentration-time curve (AUC) in the first 2 hours was 90% higher after intramuscular administration than after oral administration. For dehydro-aripiprazole, the AUC over the collection interval values were higher, the times to reach the Cmax values were later and the Cmax values were similar for the intramuscular and oral formulations. In study 2, the proportionality of the Cmax and AUC to doses ranging from 1 mg to 45 mg suggests a linear pharmacokinetic profile for intramuscular aripiprazole. Conclusion: More rapid absorption was observed following intramuscular aripiprazole injection than following oral dosing. These results support the recently reported efficacy of intramuscular aripiprazole for managing agitation in patients with schizophrenia or bipolar I disorder.

Multiple Ascending Dose Study With the New Renin Inhibitor VTP-27999 Nephrocentric Consequences of Too Much Renin Inhibition

This study compared the pharmacodynamic/pharmacokinetic profile of the new renin inhibitor VTP-27999 in salt-depleted healthy volunteers, administered once daily (75, 150, 300, and 600 mg) for 10 days, versus placebo and 300 mg aliskiren. VTP-27999 was well tolerated with no significant safety issues. It was rapidly absorbed, attaining maximum plasma concentrations at 1 to 4 hours after dosing, with a terminal half-life of 24 to 30 hours. Plasma renin activity remained suppressed during the 24-hour dosing interval at all doses. VTP-27999 administration resulted in a dose-dependent induction of renin, increasing the concentration of plasma renin maximally 350-fold. This induction was greater than with aliskiren, indicating greater intrarenal renin inhibition. VTP-27999 decreased plasma angiotensin II and aldosterone. At 24 hours and later time points after dosing on day 10 in the 600-mg group, angiotensin II and aldosterone levels were increased, and plasma renin activity was also increased at 48 and 72 hours, compared with baseline. VTP-27999 decreased urinary aldosterone excretion versus placebo on day 1. On day 10, urinary aldosterone excretion was higher in the 300- and 600-mg VTP-27999 dose groups compared with baseline. VTP-27999 decreased blood pressure to the same degree as aliskiren. In conclusion, excessive intrarenal renin inhibition, obtained at VTP-27999 doses of 300 mg and higher, is accompanied by plasma renin rises, that after stopping drug intake, exceed the capacity of extrarenal VTP-27999 to block fully the enzymatic reaction. This results in significant rises of angiotensin II and aldosterone. Therefore, renin inhibition has an upper limit. # Novelty and Significance {#article-title-16}This study compared the pharmacodynamic/pharmacokinetic profile of the new renin inhibitor VTP-27999 in salt-depleted healthy volunteers, administered once daily (75, 150, 300, and 600 mg) for 10 days, versus placebo and 300 mg aliskiren. VTP-27999 was well tolerated with no significant safety issues. It was rapidly absorbed, attaining maximum plasma concentrations at 1 to 4 hours after dosing, with a terminal half-life of 24 to 30 hours. Plasma renin activity remained suppressed during the 24-hour dosing interval at all doses. VTP-27999 administration resulted in a dose-dependent induction of renin, increasing the concentration of plasma renin maximally 350-fold. This induction was greater than with aliskiren, indicating greater intrarenal renin inhibition. VTP-27999 decreased plasma angiotensin II and aldosterone. At 24 hours and later time points after dosing on day 10 in the 600-mg group, angiotensin II and aldosterone levels were increased, and plasma renin activity was also increased at 48 and 72 hours, compared with baseline. VTP-27999 decreased urinary aldosterone excretion versus placebo on day 1. On day 10, urinary aldosterone excretion was higher in the 300- and 600-mg VTP-27999 dose groups compared with baseline. VTP-27999 decreased blood pressure to the same degree as aliskiren. In conclusion, excessive intrarenal renin inhibition, obtained at VTP-27999 doses of 300 mg and higher, is accompanied by plasma renin rises, that after stopping drug intake, exceed the capacity of extrarenal VTP-27999 to block fully the enzymatic reaction. This results in significant rises of angiotensin II and aldosterone. Therefore, renin inhibition has an upper limit.

Randomized, blinded, placebo‐ and positive‐controlled crossover study to determine the effect of multiple doses of apixaban on the QTc interval

Apixaban is an oral, direct factor Xa inhibitor indicated for the prevention and treatment of thromboembolic disease. This randomized, blinded, 4‐way crossover study investigated the potential effect of apixaban on the QTc interval. Forty healthy subjects (39 completers) each received 3 days of the following treatments: blinded apixaban 10 mg once daily (QD), 50 mg QD (supratherapeutic), matched apixaban placebo QD, and a single dose of open‐label moxifloxacin 400 mg on Day 3, preceded by 2 days of placebo QD. Triplicate electrocardiograms obtained over 24 hours on Days −1 (baseline) and 3 were read by a blinded third party. The mean placebo‐adjusted, time‐matched, Fridericia‐corrected change from baseline QTc (ΔΔQTcF) for apixaban and moxifloxacin was estimated at each time point. The maximum ΔΔQTcF was 1.51 milliseconds (one‐sided upper 95% confidence interval [CI] 3.71 milliseconds) after apixaban 50 mg QD, 1.36 milliseconds (one‐sided upper 95%CI 3.54 milliseconds) after apixaban 10 mg QD, and 10.21 milliseconds (lower 95%CI 8.07 milliseconds) after moxifloxacin. Concentration‐response analysis suggested no evidence of a positive relationship between apixaban concentration and ΔQTcF. Apixaban doses up to 50 mg QD for 3 days were well tolerated and did not prolong the QTc interval in healthy subjects.

Omapatrilat Provides Long‐Term Control of Hypertension: A Randomized Trial of Treatment Withdrawal

Omapatrilat simultaneously inhibits neutral endopeptidase and angiotensin‐converting enzyme, increasing levels of vasodilatory peptides while decreasing production of angiotensin II. This study evaluated the clinical effects of withdrawal of omapatrilat after a patients hypertension had been controlled (seated diastolic blood pressure <90 mm Hg) on omapatrilat for at least 6 months, with or without adjunctive antihypertensive medications. This double‐blind study randomized 83 patients to receive either their established omapatrilat dose or placebo for 8 weeks; any concomitant antihypertensive medications were kept constant. Patients continuing on omapatrilat had no change in blood pressure. Patients whose chronic omapatrilat treatment was replaced by placebo had clinically important increases in both systolic (+16.5 mm Hg) and diastolic (+9.6 mm Hg) blood pressures (both p<0.001). An increase in blood pressure was also seen in patients who were taking adjunctive antihypertensive medications prior to withdrawal of omapatrilat. This study demonstrates that when compared to withdrawal placebo, omapatrilat maintains clinically and statistically significant blood pressure reductions.

Multiple Ascending Dose Study With the New Renin Inhibitor VTP-27999

This study compared the pharmacodynamic/pharmacokinetic profile of the new renin inhibitor VTP-27999 in salt-depleted healthy volunteers, administered once daily (75, 150, 300, and 600 mg) for 10 days, versus placebo and 300 mg aliskiren. VTP-27999 was well tolerated with no significant safety issues. It was rapidly absorbed, attaining maximum plasma concentrations at 1 to 4 hours after dosing, with a terminal half-life of 24 to 30 hours. Plasma renin activity remained suppressed during the 24-hour dosing interval at all doses. VTP-27999 administration resulted in a dose-dependent induction of renin, increasing the concentration of plasma renin maximally 350-fold. This induction was greater than with aliskiren, indicating greater intrarenal renin inhibition. VTP-27999 decreased plasma angiotensin II and aldosterone. At 24 hours and later time points after dosing on day 10 in the 600-mg group, angiotensin II and aldosterone levels were increased, and plasma renin activity was also increased at 48 and 72 hours, compared with baseline. VTP-27999 decreased urinary aldosterone excretion versus placebo on day 1. On day 10, urinary aldosterone excretion was higher in the 300- and 600-mg VTP-27999 dose groups compared with baseline. VTP-27999 decreased blood pressure to the same degree as aliskiren. In conclusion, excessive intrarenal renin inhibition, obtained at VTP-27999 doses of 300 mg and higher, is accompanied by plasma renin rises, that after stopping drug intake, exceed the capacity of extrarenal VTP-27999 to block fully the enzymatic reaction. This results in significant rises of angiotensin II and aldosterone. Therefore, renin inhibition has an upper limit. # Novelty and Significance {#article-title-16}This study compared the pharmacodynamic/pharmacokinetic profile of the new renin inhibitor VTP-27999 in salt-depleted healthy volunteers, administered once daily (75, 150, 300, and 600 mg) for 10 days, versus placebo and 300 mg aliskiren. VTP-27999 was well tolerated with no significant safety issues. It was rapidly absorbed, attaining maximum plasma concentrations at 1 to 4 hours after dosing, with a terminal half-life of 24 to 30 hours. Plasma renin activity remained suppressed during the 24-hour dosing interval at all doses. VTP-27999 administration resulted in a dose-dependent induction of renin, increasing the concentration of plasma renin maximally 350-fold. This induction was greater than with aliskiren, indicating greater intrarenal renin inhibition. VTP-27999 decreased plasma angiotensin II and aldosterone. At 24 hours and later time points after dosing on day 10 in the 600-mg group, angiotensin II and aldosterone levels were increased, and plasma renin activity was also increased at 48 and 72 hours, compared with baseline. VTP-27999 decreased urinary aldosterone excretion versus placebo on day 1. On day 10, urinary aldosterone excretion was higher in the 300- and 600-mg VTP-27999 dose groups compared with baseline. VTP-27999 decreased blood pressure to the same degree as aliskiren. In conclusion, excessive intrarenal renin inhibition, obtained at VTP-27999 doses of 300 mg and higher, is accompanied by plasma renin rises, that after stopping drug intake, exceed the capacity of extrarenal VTP-27999 to block fully the enzymatic reaction. This results in significant rises of angiotensin II and aldosterone. Therefore, renin inhibition has an upper limit.