A study of dose-proportionality in the pharmacokinetics of the oral direct renin inhibitor aliskiren in healthy subjects.
OBJECTIVE
To evaluate the dose-proportionality of the pharmacokinetics of aliskiren, the first in a new class of orally active direct renin inhibitors approved for the treatment of hypertension.


METHODS
This was an open-label, single-center, single-dose, randomized, 4-period crossover study. Following a 21-day screening period, 32 healthy male or female subjects (ages 18 - 45 years) were randomized to 1 of 4 aliskiren dosing sequence groups (8 subjects per group): 75, 150, 300 and 600 mg. Blood samples were obtained for determination of plasma aliskiren concentrations (HPLC/MS/MS) for 96 h post dose. Log-transformed pharmacokinetic parameters AUC and C(max) were analyzed to determine dose-proportionality using the power model, parameter = A*(Dose)(beta), where A = intercept and beta = dose-proportionality coefficient. The predefined dose-proportionality criteria over the dose range 75 â 600 mg were 90% confidence intervals (CI) for beta contained within the range 0.89 - 1.11.


RESULTS
AUC and Cmax values increased with increasing doses of aliskiren. Both AUC and C(max) were associated with high variability (coefficient of variation 55 - 64% for AUC and 59 - 117% for C(max)). The estimated proportionality coefficients (beta) for AUC(0-infiniti), AUC(0-t) and C(max) were 1.18 (90% CI 1.10, 1.25), 1.29 (90% CI 1.22, 1.36) and 1.42 (90% CI 1.31, 1.52), respectively. Dose-proportionality was, therefore, not demonstrated across the entire 8-fold dose range. For the clinical dose range of 150 â 300 mg, increases of 2.3- and 2.6-fold were observed for AUC and C(max), respectively. All doses of aliskiren were well tolerated.


CONCLUSIONS
Exposure to aliskiren was greater than proportional over the dose range of 75 - 600 mg. Over the therapeutic dose range of 150 â 300 mg approved for the treatment of hypertension, AUC and Cmax increased by 2.3- and 2.6-fold, respectively. The pharmacokinetics of aliskiren show relatively high intersubject variability.
Novartis Pharma AG, Basel, Switzerland.
D
D
Limoges
H A
HA
Dieterich
C-M
CM
Yeh
S
S
Vaidyanathan
D
D
Howard
W P
WP
Dole
D000284:Administration, Oral; D000293:Adolescent; D000328:Adult; D000577:Amides / Q000008:administration & dosage* / Q000009:adverse effects / Q000493:pharmacokinetics*; D000959:Antihypertensive Agents / Q000008:administration & dosage* / Q000009:adverse effects / Q000493:pharmacokinetics*; D019540:Area Under Curve; D002851:Chromatography, High Pressure Liquid; D018592:Cross-Over Studies; D004305:Dose-Response Relationship, Drug; D005260:Female; D005650:Fumarates / Q000008:administration & dosage* / Q000009:adverse effects / Q000493:pharmacokinetics*; D006801:Humans; D008297:Male; D013058:Mass Spectrometry; D008875:Middle Aged; D000092502:Renin Inhibitors
D000577:Amides; D000959:Antihypertensive Agents; D005650:Fumarates; D000092502:Renin Inhibitors; C446481:aliskiren