TABLE 2.
Measurements of QC samples, subdivided by drug and concentration levela
| Drug | No. of measurements | Concn level | Measured concn relative to true value (%) (median [min-max]) | Absolute inaccuracy (%)b (median [min-max]) | No. and % of measurements with acceptable accuracyc | |
|---|---|---|---|---|---|---|
| Indinavir | 7 | Low | 107 (96-142) | 7 (0.7-42) | 5/7 | 80% |
| 9 | Intermediate | 106 (85-133) | 12 (4-33) | 7/9 | ||
| 9 | High | 106 (91-124) | 9 (0.2-24) | 8/9 | ||
| Nelfinavir | 6 | Low | 94 (50-150) | 28 (7-50) | 2/6 | 67% |
| 6 | Intermediate | 86 (70-126) | 18 (12-30) | 4/6 | ||
| 6 | High | 92 (83-118) | 12 (6-18) | 6/6 | ||
| Ritonavir | 6 | Low | 84 (48-184) | 30 (1-84) | 1/6 | 36% |
| 8 | Intermediate | 88 (32-134) | 18 (2-68) | 4/8 | ||
| 8 | High | 85 (39-144) | 22 (5-61) | 3/8 | ||
| Saquinavir | 7 | Low | 100 (60-138) | 15 (0-40) | 5/7 | 74% |
| 8 | Intermediate | 86 (69-137) | 15 (2-37) | 6/8 | ||
| 8 | High | 89 (75-142) | 13 (4-42) | 6/8 | ||
a
Abbreviations: min, minimum value; max, maximum value.
b
Inaccuracy is percentage bias from the true concentration, i.e., inaccuracy = (100 × measured concentration/true concentration) − 100%
c
Acceptable measurements are within 20% limits from the true concentration.