Detaljerad miljöinformation

Environmental Risk Classification

Predicted Environmental Concentration (PEC)

PEC is calculated according to the following formula:

PEC (µg/L) = (A*10⁹*(100-R))/(365*P*V*D*100) = 1.37*10^-6*A*(100-R)

PEC = 0.002 µg/L

Where:

A = 15.071 kg (total sold amount oxybutynin and oxybutunin hydrochloride in Sweden year 2021, data from IQVIA)

R = 0% removal rate (due to loss by adsorption to sludge particles, by volatilization, hydrolysis or biodegradation)

P = number of inhabitants in Sweden = 10*10⁶

V (L/day) = volume of wastewater per capita and day = 200 (Ref I)

D = factor of dilution of waste water by surface water flow = 10 (Ref I)

Predicted No Effect Concentration (PNEC)

No ecotoxicological study results are available, hence the PNEC (μg/L) could not be estimated.

Environmental Risk Classification (PEC/PNEC ratio)

The PEC/PNEC ratio could not be calculated due to lack of data and therefore justifies the phrase: "Risk of environmental impact of oxybutynin cannot be excluded, since no ecotoxicity data are available"

However, according to the European Medicines Agency guideline on environmental risk assessment of medicinal products (EMA/CHMP/SWP/4447/00), use of oxybutynin is unlikely to represent a risk for the environment, because the predicted environmental concentration (PEC) is below the action limit 0.01 µg/L.

Degradation

No data available. Therefore, the degradation phrase should be: "The potential for persistence of oxybutynin cannot be excluded, due to lack of data"

Bioaccumulation

Partition coefficient:

Oxybutynin has high potential for bioaccumulation, as indicated by a log Kow of 4.0 (estimated with EPI Suite Kow Win program on uncharged molecules).

(Ref II)

Excretion

Oxybutynin is extensively metabolized in the liver; less than 0.1% of the administered dose of oxybutynin or the main metabolite N-desethyl oxybutynin are excreted unchanged via urine. N-desethyl oxybutynin is pharmacologically active and its properties are similar to those of the parent compound. (Ref III)

References

1. ECHA, European Chemicals Agency, 2008 Guidance on information requirements and chemical safety assessment. https://echa.europa.eu/guidance-documents/guidance-on-information-requirements-and-chemical-safety-assessment

2. Fick J. et al. (2010) “Predicted critical environmental concentrations for 500 pharmaceuticals” Regulatory Toxicology and Pharmacology58: 516-523

3. Wuest M., 2008, Oxybutynin, xPharm: The Comprehensive Pharmacology Reference, 1-13