Thyroxine sodium vs levothyroxine. which one is more effective?

Stick with one: Thyroxine sodium and levothyroxine are simply different forms of generic "synthroid". Neither is better than the other. Whichever form you take, stick with it. The bioavailability of each thyroid preparation is a little different. If you switch from one form to another, your thyroid numbers may change, and you may start to feel hypo or hyper. Sometimes pharmacists switch you to save $.