Dear Alessia,

In vitro release of hydrophobic drug using HPLC:

The in vitro release study of the haloperidol-loaded PLGA nanoparticles was

carried out in triplicate in stirred dissolution cells at 37.4° C by suspending 1-2 ml of the nanoparticulate suspension in a large quantity (100-200 ml) of pH 7.4 PBS solution such that the total amount of haloperidol inside the suspended nanoparticles is less than 10% of its solubility limit in PBS buffer. This ensures the correct in vitro conditions to study the release behavior of a hydrophobic drug (Chorny et al., 2002). One ml aliquots were taken out of the dissolution cells at pre-determined time intervals, replaced by fresh PBS buffer and analyzed for released haloperidol by HPLC. The cumulative % release profiles were obtained by taking the ratio of the amount of haloperidol released to the total drug content in the same volume of sample. 

For more details, please see the methods section in the publication entitled "Controlling the In Vitro Release Profiles for a System of Haloperidol-Loaded PLGA " contained in the attached file.

Hoping this will be helpful,

Rafik

Usullay sink conditions are maintained while performing release studies. You can either add  a solubilizer (sodium dodesyl suphate) or some other surfactant such as Tween 80 (0.1%) to dissolution medium.  Or the second option is to use greater volumes of dissolution medium than that of solubility limits of the analysed drug.

Use solublizer to study in vitro release. But initially generate a method for eliminating the impact of solublizer in observation peaks.