Forteo vs teriparatide and Original Medicare Drug Plan (Part D)

I've been on Forteo (brand) since April 1 2024. By year end this year I will be on Forteo for 21 months. I just had my 18 month bone biomarker tests (CTX and P1NP) and I'm still seeing good benefit from Forteo. So my doctor and I have agreed to stay on Forteo for the full 24 months. So this leaves me with just 3 months into 2026 to use Forteo.

I'm on Original Medicare with a Part D drug plan. My current drug plan is AARP UHG. Their formulary has included Forteo (brand) all this time. AARP UHG is dropping Forteo (brand) in 2026 and replacing it with Teriparatide.

My questions:
- Is it ok to switch from Forteo to Teriparatide? I noticed that Forteo is 600mcg, 2,4ml and Teriparatide is 560mcg, 2,24ml.

- Has anyone here switched from Forteo (brand) to Teriparatide more than half way through a 24 month use?

- Has anyone used Humana Original Medicare Part D Drug Plan? It is the only Original Medicare Part D Drug Plan available to me in 2026 that includes Forteo (brand). They have a poor reputation for customer satisfaction and a record of denials in my area.