Levonorgestrel

Information

Levonorgestrel has a log P 3.8, i.e. below 4 which is the limit for a substance to be considered to have low potential for bioaccumulation. However, the substance binds to Sex Hormone Binding Globulin (SHBG), and binding to SHBG is supposed of contributing to the exceptionally high bioconcentration ability (and thus potency) observed in fish.

Estimated levels in Swedish surface water may be sufficient to interfere with reproduction in fish. Fish exposed to purified effluent accumulates levonorgestrel to concentrations exceeding the serum concentrations achieved in women using birth control pills.

Levonorgestrel is included in the Stockholm County Council's table of pharmaceuticals with risk for negative environmental impact according to the environmental program 2017–2021 based on lowest effect concentration, LOEC = 0.8 ng/L, and concentrations found in the environment.

Levonorgestrel is recommended in The Wise list.

Environmental classification of pharmaceuticals is taken into consideration, sometimes with other environmental aspects, when selecting pharmaceuticals for the Wise list. When comparable pharmaceuticals are equivalent to medical effects, safety and pharmaceutical efficacy, environmental impact and price are considered.

In comparison between levonorgestrel, norethisterone and medroxyprogesterone, medroxyprogesterone is preferred from an environmental point of view.

When using combination preparations with gestagen and estrogen, the estrogen component must also be considered. In particular, levonogestrel stands out as a drug with increased environmental risk. Environmental risk assessment is therefore relevant for both the gestagen and the estrogenic component.

In total, levonorgestrel + ethinylestradiol and etonogestrel + ethinylestradiol are considered to be the highest environmental risk, drospirenone + ethinylestradiol lower risk (based on gestagen component) and nomegestrol and estradiol lowest risk (based primarily on the gestagen component but also the estrogen component).

Suggestions on how to reduce the release of levonorgestrel

Concrete proposals on how to work to reduce emissions of environmentally harmful pharmaceuticals on the list have been developed in close cooperation with the Stockholm Drug and Therapeutics Committee's expert advice. The action proposals were developed from an environmental perspective. The patient's best always goes first and several pharmaceuticals on the list are also included in the Wise list. However, for such pharmaceuticals, there may be measures that could reduce the environmental impact.