Local tolerance of subcutaneous injections

Area of Science:

• Pharmaceutical Science
• Biotechnology
• Clinical Research

Background:

• Human insulin-like growth factor I (hIGF-I) has potential clinical applications.
• Subcutaneous administration of hIGF-I can cause injection site pain.
• Investigating formulation parameters is crucial for improving drug delivery and patient experience.

Purpose of the Study:

• To evaluate the local tolerance of different subcutaneous injection formulations.
• To determine the impact of buffer concentration and pH on injection pain and local tolerance.
• To identify optimal formulation conditions for minimizing discomfort during hIGF-I administration.

Main Methods:

• Human subjects received subcutaneous injections of various formulations with differing phosphate buffer concentrations (5-50 mM) and pH (6-7).
• Local tolerance was assessed using a visual analogue scale for injection pain, pain duration, and observation of local reactions (redness, paleness, edema).
• Isotonic saline solution served as the reference for comparison.

Main Results:

• The lowest injection discomfort was observed with 10 mM phosphate buffer at pH 7.
• Higher buffer concentration (50 mM) at pH 6 resulted in significantly greater pain compared to 10 mM phosphate at pH 6.
• hIGF-I itself did not appear to contribute to injection pain.

Conclusions:

• For subcutaneous injections requiring non-physiological pH, maintaining the lowest possible buffer strength is recommended to minimize injection pain.
• Lower buffer concentrations may facilitate quicker pH normalization at the injection site, potentially mitigating discomfort when non-physiological pH is necessary for drug stability.