Final answer:
The antidote for isoniazid overdose is pyridoxine (vitamin B6), which is used to prevent neurotoxic effects and seizures associated with high levels of isoniazid.
Step-by-step explanation:
The antidote for isoniazid toxicity is pyridoxine (vitamin B6). Pyridoxine is administered to counteract the neurotoxic effects and prevent seizures that can result from isoniazid overdose. Isoniazid itself is not used as an antidote for other substances; instead, it is a medication used primarily for treating tuberculosis. When treating isoniazid toxicity, pyridoxine is given in a dose equivalent to that of the ingested isoniazid or is administered empirically in cases of status epilepticus due to an overdose.