Quantification of beclomethasone dipropionate in living respiratory epithelial cells using Infrared Spectroscopy

Wachirun Terakosolphan, Ali Altharawi, K. L. Andrew Chan & Ben Forbes

Institute of Pharmaceutical Sciences, King’s College London,

150 Stamford St, London SE1 9NH, UK

Summary

The in situ quantification of drug in living cells is a burgeoning interest in pharmaceutical research because this information can be informative regarding drug efficacy and toxicity in patients. Infrared (IR) spectroscopy was selected as method to quantify the drug concentration entering living cells in this study. The IR technique is a non-destructive tool, widely available, but requires an additional sample compartment to conventional configurations for the investigation of living cells. The purpose of this study was to assess the suitability of IR spectroscopy for the quantification of the inhaled corticosteroid, beclomethasone dipropionate (BDP), in cultured respiratory epithelial cells (Calu-3). First, the detection limit of the instrument was evaluated by varying concentration of BDP in cell culture medium from 10 to 100 μM containing 1% v/v DMSO. A calibration curve was constructed by plotting the peak area against drug concentration from triplicate measurement. Second, the cells cultivated on the sample compartment of IR instrument were assessed for their viability. Thereafter, the cells were treated with drug solution, then monitored the change of spectrum over 24 h. We determined that it was possible to detect ~10 μM of BDP in cell culture medium using the IR instrumentation and quantify BDP over tested concentration range with a linear correlation coefficient greater than 0.99. Application of the method to cell uptake measured the uptake of BDP in living Calu-3 exposed to 80 μM drug.