(GREEN MD, MOUNT DL, WIRTZ RA, WHITE NJ. A Colorimetric Field Method to Assess the Authenticity of Drugs Sold as the Antimalarial Artesunate. Journal of Pharmaceutical and Biomedical Analysis 24:65-70, 2000.)

Items Required

1. 100 mg Fast Red TR salt
2. 20 ml sodium hydroxide (NaOH) 1 N
3. 40 ml acetic acid 1.1 M
4. 20 ml distilled water
5. Scalpel blades and gloves
6. Clean tubes, 5-10 ml volume
7. Droppers or pipettes for dispensing 0.5-1.0 ml
8. Test tube rack
9. Genuine artesunate tablet for positive control

• Prior to testing, dissolve 100 mg Fast Red TR salt in 20 ml of distilled water. The above reagents are sufficient to do ~40 tests.
• Reagents can be stored at room temperature. Wrap the tubes containing Fast Red TR salt and solution in aluminum foil to protect from light.
• Please note that the chemicals are potentially dangerous:
  • Wear gloves
  • Keep out of reach of children
  • Fast Red TR salt is an irritant and potentially mutagenic
  • Sodium hydroxide is a strong base and will cause burns
  • Dispose of the used chemicals safely after each test

Method

Test a positive control, using a known genuine artesunate tablet, and a negative control (blank, no artesunate) at each session. This is to check that the test is working correctly.

1. Scrape ~ 1% of the test 'artesunate' tablet into a clean tube and label with test number.
2. Scrape ~ 1% of the positive control artesunate tablet into a clean test tube and label as '+ control'.
3. Leave a third clean tube empty and label as '- control'.
4. Add 0.5 ml 1N NaOH to all tubes and shake gently (you should at least have 3 tubes, more if you are testing more than one suspect tablet).
5. Wait for at least 5 minutes. Some fragments of the tablets may not dissolve–this does not matter.
6. Add 1 ml of 1.1M acetic acid to all tubes and shake gently.
7. Add 0.5 ml of the Fast Red TR salt solution to all tubes and shake gently.
8. Wait 5 minutes.
9. If the solution turns yellow the tablet contains artesunate. If the solution remains colorless the tablet does not contain artesunate.
10. In order to interpret the test of the suspicious tablet, the positive control must turn yellow and the negative control MUST remain colorless. If this does not occur, repeat test.