Concentration calculator

Reconstitution math for KPV, expressed as weight/volume percent (1% w/v equals 10 mg/mL).

What this calculates

Weight/volume percent describes how much solid is dissolved in a given volume of liquid: a 1% w/v solution is one gram of material in 100 mL, which is the same thing as 10 mg/mL. The calculator multiplies your target percentage by your final volume to give the mass of KPV that volume requires.

Worked through: a 2% w/v solution at 30 mL needs 2% of 30 mL expressed as mass — 0.6 g, or 600 mg. Halve the volume and you halve the mass; the concentration is unchanged. This is arithmetic about a solution, not a recommendation about a quantity.

What to check before preparing KPV

• Starting material. KPV (free base) is described by FDA as a white to off-white lyophilized powder. FDA describes KPV acetate separately as a white to off-white solid powder. source
• Solubility. Different for the two forms, and both figures are supplier-sourced. FDA states that KPV (free base) "is soluble in water up to 0.70 mg/mL" and that KPV acetate "is reported to dissolve in water at 5 mg/mL". PROVENANCE: FDA's footnotes attribute the free-base figure to a supplier certificate of analysis and the acetate figure to a supplier product page, not to a published measurement. FDA treats the free base's low solubility as a characterisation gap, writing that because the nominator gave no formulation detail it "cannot evaluate how the physical and chemical characteristics, especially limited water solubility (0.7 mg/mL) and particle size, impact the performance of final products". source A target concentration above what the compound will dissolve produces a suspension, not a solution, and the calculator has no way to know that — it does the arithmetic either way.
• Storage. READ THE PROVENANCE BEFORE USING THIS. FDA's evaluation reports that lyophilized KPV (free base) "is stable up to 3 years when stored at -20 degrees C in a tightly closed container, up to 2 years at 4 degrees C, and up to 3 months at 15 degrees C", and that on reconstitution "the aqueous solution is recommended to be stored at -80 degrees C for 6 months, at -2 degrees C for 1 month, and 10 degrees C for 1 week". FDA's footnote attributes every one of those figures to a supplier certificate of analysis, not to a published stability study, and FDA states the conclusion as what "is reported" rather than as an agency determination. For KPV acetate, FDA reports a different condition from the nominator's certificate of analysis: "in a sealed container at 2 degrees C to 8 degrees C". There is no United States, European, Japanese or International pharmacopoeial monograph for either form and no approved product label, so no body with standing to determine handling conditions has done so. FDA separately warns that peptides "can be extremely sensitive to product formulation, process, and environmental conditions (e.g., pH, heat (temperature), concentration, in-process related impurities, excipients etc.), which may lead to the aggregation and degradation of peptides", that this "could result in loss of their biological activity", and that significant amounts of aggregates can form during storage. source

What the number does not tell you

The result assumes the vial contains the mass its label states and that the material is what the label says it is. Neither is established by arithmetic. Both come from an assay — what HPLC and mass spectrometry establish — and the published record on KPV has limits worth reading before treating any figure as settled.