Factors influencing the content of residual tert-butyl alcohol in cyclodextrin complex prepared by lyophilization cosolvent system / 药学学报

In order to minimize the residual tert-butyl alcohol (TBA) level in cyclodextrin complex prepared by freeze drying TBA/water cosolvent system, the formulation and lyophilization procedure that may influence the residual TBA was studied. Residual TBA in freeze dried cyclodextrin complex was determined by gas chromatography. The significant formulation and processing factors that influence residual TBA were identified by adjusting the initial TBA concentration in cosolvent, selecting cyclodextrin type (beta-cyclodextrin or hydroxypropyl beta-cyclodextrin), changing sample volume in flasket, altering freezing mode (fast freezing or slow freezing) and modifying the duration of secondary drying. The results show that the amorphous cyclodextrin material (hydroxypropyl beta-cyclodextrin), initial low TBA concentration in cosolvent and fast freezing would lead to high TBA residue in cyclodextrin complex, annealing was effective in reducing the residual TBA. The duration of secondary drying had no distinct effect on residual TBA. It is concluded that in order to reduce residual TBA in cyclodextrin complex prepared by lyophilization monophase solution, the initial TBA concentration in cosolvent should be higher than the crystal formation concentration, the appropriate cyclodextrin type and freeze drying processing should be choosen.

Determination of liposome/water partition coefficients of salmeterol and budesonide and study on their influencing factors / 药学学报

<p><b>AIM</b>The liposome/water partition coefficients of salmeterol and budesonide between aqueous phase and liposomes were determined and the factors that influence their partition coefficients were studied, the mechanism of interaction between the two drugs and phospholipid bilayer was elucidated.</p><p><b>METHODS</b>The liposome/water partition coefficients of the two drugs were determined by equilibrium dialysis technique. The change of the partition coefficients of the two drugs along with liposome composition and medium was also studied.</p><p><b>RESULTS</b>The partition coefficients of the two drugs decreased with the increase of cholesterol content and saturation of phospholipid used. The liposome/water partition coefficient of salmeterol increased with the increase of liposome surface negative charge, medium pH and ionic strength, while the liposome surface charge, medium pH and ionic strength had no distinct effect on the liposome/water partition coefficient of budesonide.</p><p><b>CONCLUSION</b>The liposome/water partition coefficient of drug was affected by the type, saturation of phospholipid used in liposome preparation, the cholesterol content and surface charge of liposome, as well as the pH and ionic strength of medium also have effect on the liposome/water partition coefficient of drug. Accordingly, in order to reflect the actual partition of drug in biological membrane, the determination condition including liposome composition and medium should be similar to the biological membrane.</p>