Excipient analysis could point to fake medicines

A team of Belgian researchers have developed a database of the spectroscopic signatures of commonly-used pharmaceutical excipients that could be used to identify counterfeit medicines.

The team, from Ghent University, used Raman spectroscopy to generate the signatures of 43 excipients that form the basis of a preliminary reference database that could be used for “classical qualitative and quantitative pharmaceutical analysis, counterfeit tracing and process analytical technology (PAT) applications.”

In the field of pharmaceutical analysis the focus is on the active ingredient and hardly any attention is paid to the excipients present in a medicine, note the researchers, led by Peter Vandenabeele of the university’s department of analytical chemistry.

They chose Raman spectroscopy for the analysis because it is becoming increasingly accepted as a tool in pharmaceutical research. Benefits of the approach over other methods of analysis include no need for sample preparation and the ability to study very small particles (down to 1 micron).

Using Raman it is even possible to measure through blister packages, and the technique is non-destructive.

“The recorded spectra of these excipients show clear differences and specific Raman bands and could be of help when an excipient needs to be identified, note the authors. “The identity and quality (e.g. presence of impurities) of excipients in counterfeits are often different from their corresponding authentic drugs,” they point out.
 
Prior studies have already shown that Raman spectroscopy can be an effective tool in the identification of counterfeit antimalarial tablets and Viagra tablets.

The excipients studied included:

•    mono- and disaccharides (e.g. dextrose and lactose);
•    polysaccharides (e.g. [microcrystalline cellulose and methylcellulose);
•    polyalcohols (e.g. erythritol, xylitol and sorbitol);
•    carboxylic acids and salts (e.g. alginic acid, glycine and magnesium stearate);
•    esters (e.g. peanut oil and film coatings such as Rohm Pharma’s Eudragit);
•    inorganic substances (e.g. calcium phosphate, magnesium carbonate and calcium sulfate); and
•    other widely-used excipients such as gelatine and polyethylene glycol (PEG).

“This database will be also be of great help for the identification of excipients present in genuine and counterfeit drugs or for instance illicit drugs,” conclude the researchers.

The research is published in the journal Spectroscopy Now (Volume 40 Issue 3, Pages 297 – 307).