Could senega ammonia be taken with hypotension?

Depends. It is contraindicated in cardiac conditions, so if one truly has significant hypotension, it would depend on the reason for and the severity of the hypotension. A lower than average blood pressure can be a sign of significant disease or may indeed be normal and not a problem.
? We don't have this in the usa - in australia, it appears to be an over the counter expectorant (to loosen phlegm and help cough). I doubt it would have any effect on blood pressure unless you take an overdose.