The mechanics to confirm before you commit to volume
A volume model raises specific questions a clinic should resolve before signing. Ask whether your rate is tied to a minimum monthly commitment, what happens if you fall short of it, and whether better tiers require a contract term. Ask whether the negotiated rate is per SKU or blended across your order mix, since a strong rate on one drug can mask a weaker one on another. And ask whether rates reset or renegotiate over time, because a launch rate that drifts upward changes your margin math after you have already built patient pricing around it.
The harder issue with any unpublished volume model is verification. Without public tiers, you cannot independently check whether the rate you receive reflects the volume you bring. That is not a reason to dismiss the model — aggregated demand can genuinely lower cost — but it is a reason to get the curve in writing for your SKUs rather than relying on a general claim of volume savings.