Influence of carrier (polymer) type and drug-carrier ratio in the development of amorphous dispersions for solubility and permeability enhancement of ritonavir.

The influence of the ratio of Eudragit® L100-55 or Kolliphor® P188 on the solubility, dissolution, and permeability of ritonavir was studied with a goal of preparing solid dispersions (SDs) of ritonavir. SDs were formulated using solvent evaporation or lyophilization techniques, and evaluated for their physical-chemical properties. The dissolution and permeability assessments of the functionality of the SDs were carried out. The preliminary functional stability of these formulations was assessed at accelerated storage conditions for a period of six months. Ritonavir: Eudragit® L100-55 (RE, 1:3) SD showed a 36-fold higher solubility of compared with pure ritonavir. Similarly, ritonavir:Kolliphor® P188 (RP, 1:2) SD exhibited a 49-fold higher solubility of ritonavir compared to pure ritonavir. Ritonavir dissolution from RE formulations increased with increasing ratios of Eudragit® L100-55, upto a ritonavir:carrier ratio of 1:3. The ritonavir dissolution from RP formulations was highest at a ritonavir:Kolliphor® P188 ratio of 1:2. Dissolution efficiencies of these formulations were found to be in line with, and supporting the dissolution results. The permeability of ritonavir across the biological membrane from the optimized formulations RE (1:3) and RP (1:2) were ~76 % and ~97 %, respectively; and were significantly higher compared to that of pure ritonavir (~20 %). A preliminary (six-month) stability study demonstrated the functional stability of prepared solid dispersions. The present study demonstrates that a good solubility, dissolution, and permeability improvement of ritonavir can be achieved with a careful choice of the carrier polymer, and by optimizing the amount of the chosen polymer in an SD formulation. [ABSTRACT FROM AUTHOR]