Pharmacokinetics of Saquinavir Mesylate from Oral Self-Emulsifying Lipid-Based Delivery Systems

Although lipid-based drug delivery systems have gained much importance in recent years due to their ability to improve the solubility and bioavailability of poorly soluble drugs, compartmental pharmacokinetic analyses have not been extensively explored. The oral pharmacokinetics of commercial liquid formulation and a developed semisolid system containing saquinavir mesylate (SQVM) were compared in Beagle dogs. A compartmental analysis after intravenous bolus administration of this drug (1 mg/kg) was also performed. Pharmacokinetic profiles were analyzed using both non-compartmental and compartmental approaches. Plasma concentration of the drug was determined by high-performance liquid chromatography/tandem mass spectrometry (LC/MS/MS). The disposition curve of SQVM given intravenously was better described by a three-compartment model. In contrast, plasma profiles obtained following the oral administration were fitted to a two-compartment model with lag time due to the fact that the distribution phase was masked by the absorption phase in these formulations. The proposed semisolid lipid system was found to be a promising formulation for commercial purposes given the similarity of SQVM absorption rate to that from the commercial liquid formulation.