Halothane bottles contain a small quantity of a chemical stabiliser to prevent spontaneous oxidative decomposition on storage. This stabiliser is:
- A Thymol ✓
- B Chlorbutanol
- C Benzalkonium chloride
- D Sodium metabisulphite
Correct answer: A. Thymol
Explanation
Halothane decomposes spontaneously to hydrobromic, hydrofluoric and hydrochloric acids plus phosgene when exposed to light, heat and moisture. About 0.01% thymol is added as a preservative, and the drug is dispensed in amber-coloured bottles to block ultraviolet light. Thymol is non-volatile, so it does not vaporise and accumulates in the vaporiser, which therefore needs periodic cleaning.
Reference: Morgan and Mikhail's Clinical Anesthesiology, 7th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.