LD50 value doesn't help you to decide PK dose. PK-PD is done at the efficacy doses which are relevant to humans/animals administration.

Perform PK at your efficacy dose and multiple of the same to see concentration saturation (for e.g. if efficacy is at 10 mg/kg then you can check PK at 3, 10, 30, 100 mg/kg to see dose-response).

There is no correlation between various routes, you have to adjust the doses yourself on the basis of initial screening by different routes.

For conversion of doses between species, see Table 1 in attached guideline.

Thanks for providing your valuable answer