Hi Jack,
I too have a couple of Levemir pens from when i switched over, sadly you can't do anything with them except keep as spares in the fridge, once the box is opened a pharmacy can't accept them back, there is a charity which takes surplus diabetic supplies for overseas countries which lack supplies but I doubt they would take insulin as it's a fridge item, other stuff like meters, strips, needles etc they would take (can't remember their name..). It's a shame there isn't a second home for stuff like this as would be useful to others in need.