Journal List > Transl Clin Pharmacol > v.23(2) > 1082612

Son, Kim, Chae, and Park: A quantitative approach for cardiovascular safety evaluation of a generic drug

Abstract

In generic drug development, comparative pharmacokinetic (PK) studies are conducted to assess equivalence in pharmacokinetics and safety profiles between test and reference formulations. However, there is no established quantitative approach available for safety assessment. This study aimed to propose a method for drug safety evaluation in generic drug development, as assessed by drug influence on blood pressure and heart rate change. Data were taken from a randomized, open label, 2-way cross-over comparative PK study for megestrol conducted in 39 healthy male volunteers. Vital signs of systolic blood pressure (SBP), diastolic blood pressure (DBP) and heart rate (HR) were measured at 0 (pre-dose), 4, 8, 12, 24, 48, 72, 96 and 120 hours after the dose. Safety parameters used in the analysis were area under vital sign change versus time curve to the last measured time (AUVlast) and maximum vital sign change (Vmax). Considering highly variable nature of vital signs, the scaled bioequivalence approach developed by US FDA was adopted as a decision rule for safety evaluation between formulations. With the FDA scaled approach, 90% confidence intervals of geometric mean ratio for DBP, 0.7969∼1.0377 for Vmax and 0.7304∼1.0660 for AUVlast, were both included in the equivalence ranges of 0.7694∼1.2997 and 0.6815∼1.4674, respectively, and similarly, those for HR were included in their respective scaled equivalence limits, while SBP satisfied the conventional equivalence criterion of 0.8–1.25. These results illustrate the feasibility of applying the suggested approach in cardiovascular safety evaluation in a generic drug.

References

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Figure 1.
Mean (SD) vital sign change versus time profiles of (A) systolic blood pressure, (B) diastolic blood pressure and (C) heart rate for reference (R) and test formulation (T).
tcp-23-54f1.tif
Table 1.
Demographic characteristics of the subjects
Characteristics Group 1 (n = 20) Group 2 (n = 20)
Age, yr
Mean (SD) 25.1 (1.9) 27.1 (3.9)
Range 23–31 23–40
Weight, kg    
Mean (SD) 71.6 (7.9) 67.3 (8.5)
Range 60.9–90.7 55.7–83.7
Height, cm
Mean (SD) 176.4 (5.8) 175.0 (4.4)
Range 164.8–186.4 165.8–181.5
Smoking, no. (%)
Smoker 6 (30) 9 (45)
Nonsmoker 14 (70) 11 (55)
Alcohol drinking, no. (%)
Drinker 14 (70) 13 (65)
Nondrinker 6 (30) 7 (35)
Table 2.
Scaled bioequivalence limits for highly variable drugs imposed by the FDA approach
Within-subject CV (%) Lower limit∗ Upper limit∗
30 0.7694 1.2997
35 0.7382 1.3547
40 0.7089 1.4106
45 0.6815 1.4674
50 0.6558 1.5248

These limits were obtained from the relationship that upper/lower limits = exp (±In (1.25) · tcp-23-54f2.tif) where SWR is standard deviation corresponding to within-subject variability of the reference product and SW0 is set at 0.25. See text for details.

Table 3.
Comparison of safety parameters (AUVlast and Vmax) in reference and test formulations
Parameter∗ Geometric Mean Geometric Mean Ratio Test/Reference P-value+ Residual variance CVwR (%) Scaled bioequivalence limit
Test (n= 39) Reference (n= 39) Ratio 90% CI
SBP
Vmax 19.65 19.78 0.9930 0.8804∼1.1200 0.9218 0.0992 31.49 0.7694∼1.2997
AUVlast 1201.1 1204.8 0.9978 0.8551∼1.1643 0.9809 0.1631 40.39 0.7089∼1.4106
DBP
Vmax 15.32 16.85 0.9094 0.7969∼1.0377 0.2323 0.1193 34.53 0.7694∼1.2997
AUVlast 784.8 889.4 0.8824 0.7304∼1.0660 0.2714 0.2446 49.46 0.6815∼1.4674
HR
Vmax 18.77 17.34 1.0923 0.9274∼1.2632 0.2833 0.1634 40.43 0.7089∼1.4106
AUVlast 1098.6 968.4 1.1335 0.9335∼1.3763 0.3932 0.2580 50.79 0.6558∼1.5248

Parameter units are ΔmmHg for Vmax and ΔmmHg∗h for AUVlast for SBP and DBP, and ΔBeats/min for Vmax and ΔBeats/min∗h for AUVlast for HR.

+ P-values were obtained using WinNonlin bioequivalence test with significance level of 0.05. AUVlast: area under vital sign change versus time curve to the last measured time. Vmax: maximum vital sign change. CVwR (%): coefficient of variation for within subject variability of the reference product, which was approximated as tcp-23-54f3.tif (%), in this work.

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