Tymlos pen lifespan if titrating up and not using full dose?

I believe the issue is that they've only tested the preservative for 30 days. It has nothing to do with the dose - it's the age of the medicine in the pen once it's been exposed.

People have used it for a handful of days beyond 30, but I wouldn't try to stretch it out to two months or anything like that.

I would imagine that the preservative was tested for more than 30 days but that time was set to provide a safe window that roughly corresponds with the amount of medication in the pen. Something that is safe at 11PM on the 30th day does not go bad at 1AM on the 31st day.

I believe the issue is that they've only tested the preservative for 30 days. It has nothing to do with the dose - it's the age of the medicine in the pen once it's been exposed.

People have used it for a handful of days beyond 30, but I wouldn't try to stretch it out to two months or anything like that.

susanjohnston,
I asked the endocrinologist that I see. He suggests keeping the Tymlos pen in the refrigerator. In the warmest section which I think is the butter keeper.
He says that what disturbs the molecule (degrades the hormone) is the changing of the needle. He advised me to replace the plastic cap that comes on the needle after the injection and to reuse the needle, (which I have been doing with Forteo ). I use the same needle for four days, and keep using the pen until it won't draw anymore.
The pharmacist, the manufacturer and your doctor will probably tell you to discard the pen.
But my guy is really smart.

I would imagine that the preservative was tested for more than 30 days but that time was set to provide a safe window that roughly corresponds with the amount of medication in the pen. Something that is safe at 11PM on the 30th day does not go bad at 1AM on the 31st day.

Makes sense, but the line has to be drawn somewhere, otherwise people will constantly think "what's one more day?"

Also, what we don't know is if the medication starts to become less potent after a certain point. Unfortunately, it's impossible to get an answer from the manufacturer other than "discard the pen after 30 days."