Recovery (%)
For dofetilide at three concentrations  (n=3) For amlodipine at three concentrations (n=3)
10 ng/mL 50 ng/mL 100 ng/mL Mean recovery 25 ng/mL 100 ng/mL 500 ng/mL Mean recovery
Short-termstorage                
24h (4°C) 99.47 96.55 100.87 98.96 ± 1.27 105.86 101.90 95.64 101.13 ± 2.97
24h (-20°C) 94.06 85.14 108.88 96.04 ± 6.91 98.45 95.86 99.51 97.94 ± 1.09
Mid-termstorage                
1 week (4°C) 102.84 97.61 98.77 99.74 ± 1.58 91.78 98.07 96.27 95.37 ± 1.87
1 week (-20°C) 104.92 102.31 104.44 103.89 ± 0.80 98.71 100.81 100.90 100.14 ± 0.72
Long-termstrorage                
5 weeks (4°C) 81.09 87.37 76.51 81.66 ± 3.15* 72.40 81.80 76.51 76.90 ± 2.72*
5 weeks (-20°C) 80.32 85.15 79.03 81.50 ± 1.87* 87.05 90.12 91.54 89.57 ± 1.33*
*P<0.001
Table 1: Stability of dofetilide and amlodipine in plasma samples.