Hello, my name is***** and I have over 20 years of experience as a veterinarian. I am sorry to hear that your pup ingested Zapalon pills.
This is not a drug that we routinely administer to dogs so there isn't a lot of data on the medication. The good news though is that toxicity studies showed that this drug is rarely fatal for dogs, with doses >1,000mg per kilogram or roughly 455mgs per pound body weight not causing death
But the side effects from ingestion can be horrible and include abdominal pain, dizziness, weakness, nausea, incoordination, lethargy, extreme sedation and in some dogs we can see also paradoxical (unexpected, opposite effect) excitability and inability to settle.
If we had caught her immediately I would have recommended inducing vomiting, but it is much too late for that now, as once they begin to show symptoms the drug is absorbed.
It may be best at this point to have her hospitalized for observation and fluid therapy. There are drugs that can help reverse the effects, such as flumazenil, but they are prescription medications.
If you do not have access to veterinary help tonight all you can do is confine her in a small quiet area so she cannot hurt herself and give the drug time to be metabolized. The more she ingested the longer this will take, but I would expect her to be much better in 24 hours.
Please let me know if you have any further questions.