Intravenous Pharmaceuticals

Pharmaceuticals and their metabolites are commonly detected in the environment (air, soil, and water), including in tap water. Those most commonly tested for in water samples include analgesics, antibiotics, beta blockers, estrogens and other hormonal compounds, psychostimulants, and anti-epileptics.⁹⁷ Less is known about transformation products of pharmaceuticals, which are even more abundant than parent compounds. While pharmaceutical pollution concentrations are typically subtherapeutic, the cumulative and synergistic effects of micro exposures are unknown and particularly concerning for pregnant women and children because of increased susceptibility during growth and development.⁹¹

Intravenous medications commonly enter the environment, both directly via the disposal of unused drugs and indirectly via human excretion, because sewage treatment facilities are inadequately designed to transform pharmaceutical waste products. General strategies anesthesiologists can take to prevent pollution include avoiding unnecessary use and excess preparation of medications, preferentially selecting medications that minimize environment impact when clinically appropriate, and proper waste disposal.

Careful attention to appropriate dosing and whether or not a medication is indicated are important strategies for resource stewardship and pollution prevention. For example, patients may receive supratherapeutic doses of propofol during induction if care is not taken to adjust for age and health status.⁹¹ This often requires subsequent treatment of hypotension with phenylephrine, ephedrine, or other medications that may have been avoided.

Excessive preparation of medications is another common problem in anesthesiology.^98-100 The USP⁹⁶ sets guidelines for storage and handling of drugs. Whereas drugs opened and prepared by anesthesiologists must be disposed of within a matter of hours, those prepared under Level V laminar hoods may keep for days to months depending on refrigeration conditions. Important strategies to avoid waste include not opening and preparing medications unless they are indicated and using “pre-filled” syringes and bags prepared either by in-house pharmacy departments or third-party vendors. An important group of drugs that many institutions commonly outsource for prefilling are emergency or “just in case” medications.⁹⁸ In addition to reducing pollution through increasing the shelf life, ready-to-use medications can improve patient safety by reducing anesthesiologists’ time and distraction errors and have been recommended by the Anesthesia Patient Safety Foundation.¹⁰¹

To guide environmentally preferable clinician prescribing, the Stockholm County Council created the Wise List.¹⁰²

Medications are classified based on: 1) environmental risk (the ratio of the predicted concentration to the safe environmental drug concentration), and 2) environmental hazard (a nine-point index based on persistence, bioaccumulation, and toxicity, or PBT index). Of note, the PBT index is based on risk (potential harm) and hazard (the likelihood of harm) from exposures and does not reflect actual environmental contamination. Further, as the use of one medication often influences future decisions (e.g., propofol maintenance decreases indication for prophylactic antiemetics), the total environmental impact of medications administered during an anesthetic should be considered and not simply the PBT index of any single medication.

Finally, the proper disposal of unused perioperative medications is key to avoiding unintended deleterious effects on global water sources and ecosystems, as well as mitigation of greenhouse gas emissions. (See Waste Disposal Management).

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