Tone, and why a solute matters

Water with only alcohol in it is weaker in tone than your blood, and the label is direct about the consequence: given into a vein without a solute it can break red cells. Dissolving a powder in it adds that solute, and the volumes used under the skin are tiny against the tissue fluid waiting to dilute them. The pH sits near 5.7, mildly acidic, which suits most peptide chains and keeps them in solution.