Environmental Impact of Propofol

Toxicity

• Propofol (2,6 diisopropylphenol) is manufactured in a lipid-based emulsion and contains preservatives which differ based on the manufacturer.
• Propofol is not biodegradable. It has been shown to contaminate water and is toxic to aquatic life. It has the potential to accumulate in organisms due to its fat solubility.² It can exist in the soil and as a vapor in the atmosphere. It is noted to have some soil mobility, which indicates the potential for it to leach or runoff into other bodies of water. One estimate of propofol’s volatilization half-life from a model pond was about 6.5 years.
• A common preservative in propofol is ethylene diamine tetra acetic acid (EDTA), which has its own environmental concerns. While there are technologies that use EDTA to recondition soil for agricultural use, it can also persist in soil and aquatic environments causing changes to algae growth, undesired transport of radioactive metals from disposal sites, and cellular changes in mammals.

Waste Generation and Disposal

• Discarded (wasted) propofol makes up the largest fraction by volume of pharmaceutical waste from the operating room. While emergency medications such as succinylcholine, atropine, ephedrine, and epinephrine are wasted more frequently, the large volume of propofol required for clinical use leads to its high volume of waste, especially when large-volume vials (50mL and 100mL) are available.
• The waste fraction (the volume of unused medication compared to the administered volume) of propofol is best reduced by utilizing incremental preparation of medications rather than drawing up a large volume to start. A study of 8 operating rooms over 10 months found that 32% of propofol drawn up was unused and wasted. Waste was reduced ten-fold by removing 50mL vials of propofol and replacing them with 20mL vials. Smaller vials (10mL) are available and should be considered for pediatric use.⁵
• Estimating the required amount of propofol needed for a case, especially for an infusion, also reduces the amount of drug wasted. This can be done with apps or online calculators.^6,7 Propofol Dreams is an app designed to reduce propofol wastage.⁶ The sustainability in anesthesia blog has a calculator to estimate the amount of propofol needed for a case based on the patient’s weight and duration of the procedure.⁷
• It is also important to note that propofol is stable for 12 hours after it is drawn up.^8,9 The length of time has significantly increased from the traditionally cited 6 hours and may provide another waste-reducing strategy. It is possible for propofol to separate or appear discolored prior to that time, and in those cases the medication should be discarded.

• If propofol is mixed with lidocaine, it should be used quickly afterwards as it can separate into large globules, which may increase the risk of embolism injuries.^9,10 As with all medications, propofol should be inspected prior to use if it was prepared earlier than just prior to planned usage.

Practice Changes

• Propofol should not be disposed of down the drain/toilet due to its environmental toxicity.
• Propofol should be incinerated.
• Large volume vials of propofol should be replaced with smaller volume ones.
• Infusion calculators should be used whenever possible.
• Drawn syringes of propofol can be used for a longer time (up to 12 hours) if they appear otherwise normal.