Hi, I am Dr. Peter and would like to help.
1- Do you have hydrogen peroxide?
Benzonatate is one of the cough medicine we use; usually at doses between 25-100mg. Not seeing any of the pills in the vomit could mean either the pills were absorbed or he did not swallow it. Possible side effects include numbness of the mouth or tongue, tremors and even seizures. I would recommend to observe him, if you do not see any symptoms within the next 12 hours than he will be fine. But, if he begins to act agitated or tremors, have him checked by a veterinarian immediately.
If you have additional questions I will be glad to answer them.
is it ok to let him eat his regular meal this evening (6pm PT)?
Can he have water?