Enalapril in RAPIDISC (wafer formulation): pharmacokinetic evaluation of a novel, convenient formulation.
BACKGROUND
Enalapril in RAPIDISC* (wafer), a new easy-to-administer formulation of enalapril, may improve the convenience of enalapril therapy, thereby helping patients adhere to antihypertensive treatment.


METHODS
To determine whether 20 mg enalapril wafer is bioequivalent to the conventional 20 mg enalapril tablet, an open-label, two-period crossover study was performed in 16 healthy male volunteers. Cumulative urinary recovery of free enalaprilat (active metabolite of enalapril) and the serum maximum concentration of free enalaprilat (Cmax) were the primary pharmacokinetic parameters used to determine bioequivalence in this study. Bioequivalence was defined as the geometric mean ratio (wafer: tablet) falling within the equivalence limits of 0.80 to 1.25 for both parameters.


RESULTS
Cumulative urinary recovery of free enalaprilat (0 - 72 hours) was similar between the wafer and conventional tablet formulations (arithmetic mean 5.13 vs. 5.03 mg, about 36% of dose). The geometric mean ratio of the urinary recovery of free enalaprilat (wafer: tablet) was 1.03 (90% CI: 0.93, 1.15). Cmax of serum enalaprilat was also similar between the wafer and conventional tablet formulations (arithmetic mean 85.7 vs. 76.3 ng/ml). The geometric mean Cmax ratio (wafer: tablet) was 1. 10 (90% CI: 1.00, 1.22). Both enalapril formulations were well tolerated.


CONCLUSIONS
This study demonstrates that 20 mg enalapril in RAPIDISC is bioequivalent to 20 mg enalapril conventional tablet.
Drug Metabolism, Merck Research Laboratories, West Point, PA 19486-0004, USA.
Lo M-W
J B
JB
McCrea
C R
CR
Shadle
M
M
Hesney
R
R
Chiou
D
D
Cylc
A S
AS
Yuan
M R
MR
Goldberg
D000328:Adult; D000806:Angiotensin-Converting Enzyme Inhibitors / Q000008:administration & dosage / Q000009:adverse effects / Q000493:pharmacokinetics*; D019540:Area Under Curve; D018592:Cross-Over Studies; D004305:Dose-Response Relationship, Drug; D004656:Enalapril / Q000008:administration & dosage / Q000009:adverse effects / Q000493:pharmacokinetics*; D006801:Humans; D008297:Male; D013810:Therapeutic Equivalency
D000806:Angiotensin-Converting Enzyme Inhibitors; D004656:Enalapril