Ciproflaxin and zanaflex (tizanidine) together no good , why ?

Hepatic inhibition: Basically Cipro (ciprofloxacin) decreases the ability of the liver to metabolize (process) tizanidine (zanaflex). This will increase the levels of tizanidine in the body. With this there is a significant risk of hypotension (very low blood pressure), bradycardia (very low heart rate), and changes in mental and physical activity abilities (psychomotor impairments). In other words can be dangerous.

Zanaflex (tizanidine) cant clear: Cipro (ciprofloxacin) is cleared by a specific enzyme system in the liver, and its the same one Zanaflex is cleared by. However, Zanaflex blocks much of these enzyme complexes, making it so Zanaflex can not clear the blood stream. This leads to an increased amount of Zanaflex in the blood stream and therefore makes the drug much more potent.