The calculator confusion that keeps coming up when people switch compounders is almost always because two things changed simultaneously and they’re treating it like one. Variable one: concentration. Southend 22mg/4mL is 5.5mg/mL. BPI 60mg/3mL is 20mg/mL. Yes, this changes your units per mg and yes it needs to go into Fat Scientist. Variable two: the prescriber may have also changed your dose when they wrote the new rx. If you were on 5mg and the new script says 11mg, that’s a dose escalation baked into the new prescription, not just a unit conversion. When both shift at once the calculator can only solve for one at a time. You have to know which dose you’re actually targeting before the concentration math matters. The 68-unit vs 55-unit gap is the tell.
At 20mg/mL, 11mg = 55 units on a U-100 syringe. That’s just arithmetic. If your printed rx says 68 units for 11mg, then either the prescriber calculated off a different concentration than what’s on the label (this happens more than people think, especially when the pharmacy communicates formulation details verbally or the script was written before final compounding was confirmed), there’s an overfill correction built in, or there’s a syringe calibration mismatch. Those are different problems with different fixes. The B6 piece adds one more wrinkle. Both formulations are tirz w/B6 but the B6 mg/mL ratio isn’t necessarily preserved when concentration changes. If Southend had a fixed B6 amount per mL and BPI doesn’t scale it proportionally to the new concentration, your B6 dose at the new injection volume will be different. imo Usually not clinically significant, but it’s another assumption nobody checks. Call the pharmacy and ask what concentration number they gave your prescriber when the rx was written. That number is what goes in the calculator, not just what’s on the label.