Table 2

Effect of starting dose on theoretical Phase I trial efficiency

Number of modified Fibonacci dose levels required with a single dose schedule to reach the MTD if the starting dose were determined from one-third the LD10 or TDH versus one-tenth the LD10 or one-sixth the TDH.
Fraction of LD10 or TDHDifference
1/10 or 1/6a1/3
Mouse8.9 ± 0.6b4.7 ± 0.54.2
(6–11)(3–7)
Rat7.8 ± 0.53.9 ± 0.43.9
(4–10)(2–6)
Most sensitive rodent9.2 ± 0.54.8 ± 0.44.4
(7–11)(3–7)
Dog5.9 ± 0.53.3 ± 0.32.6
(3–7)(2–4)
  • a One-tenth the rodent LD10 or one-sixth the nonrodent TDH.

  • b Mean ± SE (range).