Buffers

Buffers are solutions that resist any change in pH upon addition of small amounts of acid or alkali.
The solubility and stability of the preparation is significantly affected by the pH of the preparation. The ideal pH of a parenteral product is 7.4. Variations from this pH may cause tissue necrosis and extreme pain while administration.
The usual pH range for parenteral preparations is between 3.0 and 10.5. This is because the blood itself can act as a buffer and can dilute and distribute the solution rapidly in the circulatory system.
The commonly employed buffers are acetic acid, lactic acid, maleic acid, sodium phosphate dibasic, sodium acetate, sodium bicarbonate and tartaric acid.
The concentration of buffer used ranges from 0.1% to 2.0%.