Fixed Dose Procedure

The fixed-dose procedure (FDP) was proposed in 1984 to assess a substance's acute oral toxicity using fewer animals with less suffering than the older LD50 test developed in 1927.

FDP uses 10-20 animals to find the dose producing toxicity signs but not death, and from there predicts the lethal dose. LD50 ("lethal dose 50%") uses 60-80 animals to find a dose killing 50% of animals within a given time. FDP sometimes requires retesting using slightly higher or lower doses.