Co-Solvents

•Used to increase aqueous solubility of weak electrolytes and non-polar molecules

•Solute more soluble in mixture of solvents (alcohol/water mixture)

•Examples:

  --Propylene glycol

  --Polyethylene glycol

  --Glycerin

  --Alcohol

•Valium (Diazepam) Injection 5mg/mL

–40% Propylene Glycol

–10% Alcohol

–5% Na Benzoate/Benzoic Acid

–1.5% Benzyl Alcohol

–QS Purified Water

•Diazepam – crystalline, insoluble in water