I may as well post a few more details, as the core of the poison system I used has already been explained.
Short interval: 10 + Con mod (of the poisonee) rounds per interval (~1 minute)
Mod interval: 100 + (2*Con mod) rounds per interval (~10 minutes)
Long interval: 1,000 + (10*Con mod) rounds per interval (~ 1 hr, 40 min)
For purified / supernatural / (otherwise extraordinary) poisons:
Very Short interval: 1 + (half Con mod) round(s)
Very Long interval: 10,000 + (50*Con mod) rounds per interval (~ 16 hrs, 40 min)
Hemotoxins (various types): affect Con
Neurotoxins (various types): affect Dex
Myotoxins (few types): affect Str, rarely lead to death in the real world, however, so damage is only high in supernatural cases
Cytotoxins (few types): little effect except extremely locally, tends to worsen affects of other toxins, so I presume this causes a normally 'ability damage' toxin to instead act like an 'ability drain' toxin.
A collection of un-categorized toxins cause a variety of other effects upon a failed save (fort or will, depending). These can range from sleep to nausia to hallucinations, etc. I will likely choose one or two effects for each ability score. Note that I categorize substances that affect physical abilities as poisons and substances that affect mental abilities as drugs. Toxin is a catch-all word encompassing both.
Creatures are typically limited to twice their Con mod in toxins per day (ie: a venomous bite or a sting - and this is being generous). The number of intervals a poison has is related to the Con mod of the creature it came from. As this mod also affects the DC of the poison, this typically means that poisons with great intensity last longer - a (possibly) realistic effect.
Delay Poison would work by allowing the character to skip their next interval (ie: not needing to make a save). They would, however, still have the same number of intervals to deal with after. If multiple poisons are within the person, each would have the next interval skipped - offset until later.
Neutralize poison would allow for an autosave upon the next interval for each poison within the character.
I've not yet decided whether to add the facet I use in the disease system for saves (one save and the disease is in remission in the current stage, two and the character moves back a stage - until no more saves exist and the character is cured). In that system Remove Disease simply autosaves and moves the character back a stage in the disease. If a similar system were worked into Poisons than two saves in a row (for a specific poison) might allow for overcoming the (specific) poison - no longer needing to make saves for it. In such an situation two successive castings of Neutralize Poison would cure a person of any poison.
I may or may not add this, for if I added this I would have to add the opposite: two successive failures causes the character to take maximum ability damage (1d4 results in 4, for instance) and the character decends to the next stage of the disease even if it is sooner than normal. In the case of poisons I'm not sure how I would work that - perhaps cause (upon second successive failure for a specific poison) maximum die damage (1d4 results in 4, etc) and an immediate save for the next interval - ie skipping the normal duration of time. That could make a person die real fast even with the lower damage die I would typically use in my system.