The first part of your post has confused me a little I must admit!
In answer to the second part, if you are taking it for nausea, take the recommended dose - 25-50mg. It's a sedating antihistamine too (related to hydroxyzine) so will probably add to the overall opiate/sedative experience. I wouldn't take much more of it - it's also an anticholinergic, which can have pretty nasty side effects (dry mouth, urinary retention, horrible delirium).
Also - if you have all 4 pills you will be having 3g of APAP. This is too much really - shouldn't be more than 1g in one go, every 4-6 hours. You can have up to 4g in 24 hours but you shouldn't have it all at once as your liver will be a little overworked! 3g would probably be fine in most people as a very occasional thing but everyone is different and liver damage can occur at really low doses so it's always best to get into the habit of doing a CWE. I appreciate this might seem overkill for just 4 pills and as I said you would probably be okay but in the interests of harm reduction I felt I should warn you of the risk!
