As the pH of most body fluids is 7.4, products such as injections, eye drops and nasal drops should, in theory, be buffered at this value to avoid irritation.
Many body fluids themselves, however, have a buffering capacity and, when formulating low volume intravenous injections or eye drops, a wide pH range can be tolerated.
This is potentially useful should a compromise be necessary when choosing a pH that is physiologically acceptable for a drug whose optimum stability, solubility and absorption may depend on different pHs.
Buffering at a pH of 7.4 can help to maintain the stability and effectiveness of the drug in the body, as well as reduce the risk of irritation when administered. Additionally, it can help to minimize any potential side effects that may occur due to changes in pH.
Overall, it is important to consider the pH of body fluids when formulating pharmaceutical products to ensure optimal efficacy and tolerance by the body.