Detaljerad miljöinformation

Detailed background information

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 = 0.38 μg/L

Where:

A = 2790.5467 kg (total sold amount API in Sweden year 2021, data from IQVIA). Reduction of A may be justified based on metabolism data.

R = 0% removal rate (conservatively, it has been assumed there is no 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 (ECHA default) (Ref. I)

D = factor for dilution of waste water by surface water flow = 10 (ECHA default) (Ref. I)

Predicted No Effect Concentration (PNEC)

Ecotoxicological studies

Green Algae (Scenedesmus subspicatus):

IC50 96h (growth) = 4,500 μg/L (OECD 201) (Reference 9)

NOEC = 625 μg/L

Water flea (Daphnia magna):

Acute toxicity

EC50 48 h (immobility) = 3,800 μg/L (OECD 202) (Reference 15)

Water flea (Ceriodaphnia dubia):

Chronic toxicity

NOEC 7 days (reproduction) = 400 μg/L (USEPA 1002) (Reference 14)

Rainbow Trout (Oncorhyncus mykiss):

Acute toxicity

LC50 96 h (lethality) = 33,000 μg/L (OECD 203) (Reference 8)

Fathead minnow (Pimephales promelas):

Chronic toxicity

NOEC 32 days (growth) = 100 μg/L (OECD 210) (Reference 14)

Other ecotoxicity data:

Microorganisms in activated sludge:

EC50 3 h (inhibition) > 100,000 μg/L @ 3 hrs (OECD 209) (Reference 11)

NOEC = 100 000 μg/L

Microbial Growth Inhibition:

EC50 (inhibition) > 1,000,000 μg/L (TAD 4.02) (Reference 7)

PNEC = 100/10 = 10 μg/L

PNEC (μg/L) = lowest NOEC/10, where 10 is the assessment factor applied for three long-term NOECs. NOEC for fathead minnow (= 100 ug/L) has been used for this calculation since it is the most sensitive of the three tested species.

Environmental risk classification (PEC/PNEC ratio)

PEC/PNEC = 0.38/10= 0.038, i.e. PEC/PNEC ≤ 0.1 which justifies the phrase “Use of bupropion has been considered to result in insignificant environmental risk.”

Degradation

Biotic degradation

Ready degradability:

1.21% degradation in 14 days (TAD 3.11) (Reference 6)

Inherent degradability:

0% ultimate biodegradation in 14 days (OECD 302) (Reference 12)

90% primary degradation in 14 days

This may be regarded as evidence for inherent primary biodegradation. This substance is not inherently biodegradable.

Abiotic degradation

Hydrolysis:

50% degradation @25^oC in 16.7 days (pH 7.4) (TAD 3.09) (Reference 4)

Photolysis:

50% degradation in 48 h (TAD 3.10) (Reference 5)

Justification of chosen degradation phrase:

Bupropion is not readily degradable but it does undergo inherent primary biodegradation. This substance is predicted to degrade via hydrolysis and the half-life is less than 40 days. However, the relevant degradation products have not been identified or characterised. The phrase “Bupropion is potentially persistent” is thus chosen.

Bioaccumulation

Partitioning coefficient:

Log Dow = 1.54 at pH 7.4 (TAD 3.02) (Reference 3)

Log Dow at pH 1.2 = -0.6

Log Dow at pH 6.0 = -0.1

Log Dow at pH 7.4 = 1.54

Justification of chosen bioaccumulation phrase:

Since log Dow < 4 at pH 7, the substance has low potential for bioaccumulation.

Excretion (metabolism)

Bupropion is excreted to 0.5% as parent compound and to 96.50% as metabolites. The pharmacological activity of the metabolites is not known. (Reference 2)

Metabolites

Bupropion is extensively metabolised in humans. Three pharmacologically active metabolites have been identified in plasma: hydroxybupropion and the amino-alcohol isomers, threohydrobupropion and erythrohydrobupropion. These may have clinical importance, as their plasma concentrations are as high or higher than those of bupropion. The active metabolites are further metabolised to inactive metabolites (some of which have not been fully characterised but may include conjugates) and excreted in the urine (Reference 2).

Excretion

Following oral administration of 200mg of 14C-bupropion in humans, 87% and 10% of the radioactive dose were recovered in the urine and faeces, respectively. The fraction of the dose of bupropion excreted unchanged was only 0.5%, a finding consistent with the extensive metabolism of bupropion. Less than 10% of this 14C dose was accounted for in the urine as active metabolites (Reference 2).

PBT/vPvB assessment

Bupropion does not fulfil the criteria for PBT and/or vBvP.

All three properties, i.e. ‘P’, ‘B’ and ‘T’ are required in order to classify a compound as PBT (Reference 1). Bupropion does not fulfil the criteria for PBT and/or vBvP based on log Pow < 4.

Please, also see Safety data sheets on http://www.msds-gsk.com/ExtMSDSlist.asp.

References

1. ECHA, European Chemicals Agency. 2008 Guidance on information requirements and chemical safety assessment.

   
   

2. Pharmacokinetic properties: Meatbolism and Elimination. Summary of Product Characteristics Zypan 150mg (Bupropion hydrochoride). GlaxoSmithKline, March 2011.

   
   

3. Morgan TA. Determination of the Octanol/Water partition Coefficient of Bupropion hydrochloride. Burroughs Wellcome Notebook 75/3694. Burroughs Wellcome Physical Pharmacy Group, April 1976.

   
   

4. Whisler MFS. Bupropion hydrochloride: Physical and Chemical Characteristics. Report No. GFZZ/94/0025/02.

   
   

5. Williams MD. Aqueous Photodegradation of Bupropion hydrochloride. Report No. 41081. ABC Laboratories, November 1993.

   
   

6. Williams MD. Aerobic Biodegradation in Water Using 14-C-Bupropion hydrochloride. Report No. 41082. ABC Laboratories, October 1993.

   
   

7. Williams MD. Microbial Inhibition with Bupropion hydrochloride. Report No. 41083. ABC Laboratories, October 1993.

   
   

8. Sewell IG and Mullee DM. Bupropion hydrochloride: Acute Toxicity to Rainbow Trout (Oncorhynchus mykiss). Report No. 307/837R. Safepharm Laboratories Limited, March 2001.

   
   

9. Mead C and Mullee DM. Bupropion hydrochloride: Algal Inhibition Test. Report No. 303/836R. Safepharm Laboratories Limited, March 2001.

   
   

10. Sewell IG and Mullee DM. Bupropion hydrochloride: Fish, Early Life-Stage Toxicity Test. Report No. 1127/1401. Safepharm Laboratories Limited, November 2007.

    
    

11. Swarbrick RH, Smyth DV, Kent SJ.. Bupropion hydrochloride: Effect on the Respiration Rate of Activated Sludge. Report No. BL7709/B. Brixham Environmental Laboratory, July 2004.

    
    

12. Swarbrick RH, Smyth DV, Kent SJ. Bupropion hydrochloride: Determination of Inherent Biodegradability (Zahn-Wellens test). Report No. BL7710/B. Brixham Environmental Laboratory, November 2004.

    
    

13. Swarbrick RH, Smyth DV, Kent SJ. Bupropion hydrochloride: Determination of Adsorption onto Activated Sludge (batch test). Report No. BL7711/B. Brixham Environmental Laboratory, September 2004.

    
    

14. Young BE and Kent SJ. Bupropion hydrochloride: Determination of 3 Brood (7 day) Chronic Toxicity Test to Ceriodaphnia dubia. Report No. BL8149/B. Brixham Environmental Laboratory, March 2006.

    
    

15. Material Safety Data Sheet for Zyban® Sustained-Release Tablets. SDS number 110591. GlaxoSmithKline plc, August 2008.