(W1130-06-32) In Vitro Model to Study the Lymphatic Voyage of Drugs via Artificial Chylomicrons

Purpose: Lymphatic drug uptake through chylomicrons (lymph-carried species produced by intestinal cells) is an important determinant of pharmacokinetics and pharmacodynamics. However, the biophysics of in-vitro systems and prediction of in-vivo lymphatic disposition has not been mechanistically examined^1,2. The aim of this study was to investigate the oral lymphatic uptake of drugs, their enhancement, and inhibition via a novel in-vitro model.

Methods: The intestinal lymphatic system was mimicked in-vitro using Franz cells and intralipid (a lipid emulsion resembling chylomicrons)³. Solutions of model lymphotropic drugs (rifampicin, cannabidiol, and quercetin) were added to the donor compartment at different concentrations (0.5-2 mg/ml). The receiver compartment was maintained at 37.0±0.5 °C and magnetically stirred at 600 rpm. It was filled with either intralipid or intralipid containing other xenobiotics acting as lymphatic uptake enhancers or inhibitors. Pluronic L-81 (0.1%-15%) acted as an inhibitor and sesame oil (2%) was used as an enhancer. Octanol-immersed 0.22 µm Polyvinylidene Fluoride (PVDF) membranes were utilized to separate the compartments. At different intervals, 0.2 ml samples were taken and extracted with organic solvents (extraction efficiency >92%) before HPLC analysis to determine the rate and extent of uptake over time. Particle size distribution of the intralipid alone and with the pluronic was determined via a zeta sizer to investigate the mechanism of inhibition in this model.

Results: The cumulative percentages of the different drugs of the same concentration (1 mg/ml) in the receiver compartment were determined as follows: 12.05%, 33.29%, and 36.12% for rifampicin, cannabidiol, and quercetin, respectively. The receiver compartment contained 0% of rifampicin when 15%, 10%, and 1% of the pluronic were used and nearly 50% of what was reported before with 0.1% pluronic. PL-81 was found to increase the particle size of the lipid droplets in the used receiver compartment media (intralipid) from a mean diameter of 79.72 nm to 206.1 nm. However, adding lipids with a 2% sesame oil increased the percentage of rifampicin in the receiver compartment 5 fold compared to control.

Conclusion: The presented in-vitro model demonstrated its ability to mimic drug uptake into chylomicrons and the inhibition of this process. The new model showed promising results that can potentially be used to study and predict the lymphatic drug uptake and excipient effects to enhance or inhibit this process. Food and formulation effects might also be examined through it.

References: 1. J Pharm Pharm Sci. 2021 24: 533-547
2. Acta Pharm. Sin. B. 2021 11: 2449-2468
3. Biochim. Biophys. Acta, Lipids Lipid Metab. 1991 1086:265-272.

Acknowledgements: Malaz Yousef is supported by MITACS Accelerate Internship. Opinions, interpretations, and conclusions are those of the authors and not necessarily endorsed by the funding agency.


Table 1. Cumulative percentages of the tested drugs in the receiver compartment of the model till reaching a maximum value (% of in-vitro lymphatic uptake)


Table 2. Inhibition of the drug movement into the receiver compartment of the model when different percentages of pluronic L-81 were used.


Table 3. Comparison of the in-vitro lymphatic uptake of rifampicin via the developed model when 2% sesame oil was added to the receiver compartment medium.