MRS and Medication Response: A Pilot Study

The primary objective of this study is to demonstrate that it is feasible to image paroxetine (Paxil) or citalopram (Celexa) or escitalopram (Lexapro) brain concentrations using MRS technology in depressed patients. The longer-term goal is to determine the relationship between clinically administered doses of paroxetine (Paxil) or citalopram (Celexa) or escitalopram (Lexapro) (antidepressants), the amount of drug in the body via blood level, the concentrations of the drug achieved in brain measured via MRS, and genetics. It has been previously reported that individuals taking 20mg of paroxetine daily had brain paroxetine \[(Paxil) levels via MRS ranging from 2-13 micromolar. Similar or slightly higher ranges of brain drug concentrations have been reported for fluoxetine and fluvoxamine. Since not all depressed patients respond to medications, one reason may be the amount of medication that crosses the blood-brain barrier. This may be influenced by genetic information. We want to examine these issues on a larger scale, but first we need to demonstrate that we can indeed determine paroxetine \[(Paxil) or citalopram (Celexa) or escitalopram (Lexapro)\] levels via MRS. Intended results analysis could not be conducted because a reliably sensitive spectroscopic method could not be developed.