Miljöpåverkan
Balsalazid
Miljörisk:
Risk för miljöpåverkan av balsalazid kan inte uteslutas då ekotoxikologiska data saknas.
Nedbrytning:
Det kan inte uteslutas att balsalazid är persistent, då data saknas.
Bioackumulering:
Balsalazid har låg potential att bioackumuleras.
Läs mer
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) = 1.5*10-6*A(100-R)
PEC = ¶ 0.00015xA
PEC = 3.47 μg/L
¶
Where:
A = 23110.835 kg (total sold amount API [prodrug and active metabolite] in Sweden year 2017, data from IQVIA).
R = 0% removal rate (due to loss by adsorption to sludge particles, by volatilization, hydrolysis or biodegradation) (no data is available).
P = number of inhabitants in Sweden = 9 *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)
Ecotoxicological studies
Risk of environmental impact of balsalazide cannot be excluded, since no ecotoxicity data are available.
Degradation
Balsalzide is a pro-drug, which is metabolized in the gut to mesalazine, responsible for the anti-inflammatory action, and the inert carrier molecule metabolite.
Ready degradability: Mesalazine showed >90% degradation over 28 days (Ref II), hence justifying the degradation phrase:
"The potential for persistence of Balsalazide can not be excluded, due to lack of data.”
Bioaccumulation
Partitioning coefficient:
Log Pow balsalazide (the prodrug) = 1.3 at neutral pH (experimentally derived, method unknown) (Ref III).
Log Pow mesalazine (the active metabolite) = 1.2 at neutral pH (experimentally derived, method unknown) (Ref IV).
Justification of chosen bioaccumulation phrase:
Since Log Pow < 4 at pH 7, balsalazide and its active metabolite have low potential for bioaccumulation.
Excretion (metabolism)
Most of the dose is eliminated via the faeces but about 25% of the released mesalazine appears systemically predominantly as the N-acetylated metabolite (NASA) after inactivation in the colonic mucosa and liver. The systemic uptake of 4-ABA is only 10-15% of that of mesalazine and also this metabolite is grossly N-acetylated (to NABA) in the first pass. (Ref V)
In urine, virtually only NASA and NABA are recovered and their renal clearances are high: 0.2-0.3 L/min and 0.4-0.5 L/min, respectively. The half-life of NASA is in the order of 6-9 hours. The half-life of mesalazine itself is very short: about 1 hour. (Ref V)
Because of the great importance of renal clearance for the elimination, Colazide should be used with caution in renal impairment. No studies have been performed in patients with hepatic disease. (Ref V)
Protein binding of mesalazine is about 40% and that of NASA about 80%. Available data suggest that the pharmacokinetics of balsalazide is not affected by genetic polymorphism, nor does age seem to be an important factor. Fasting slightly increases the systemic uptake of balsalazide and its metabolites. (Ref I)
References
Ref I. 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
Ref II. Summerton L, Sneddon HF, Jones LC, Clark JH. Green and Sustainable Medicinal Chemistry: Methods, Tools and Strategies for the 21st Century Pharmaceutical Industry. 2016.
Ref III. Drug bank web page, assessed as of March 2019. https://www.drugbank.ca/drugs/DB01014
Ref IV. Drug bank web page, assessed as of March 2019. https://www.drugbank.ca/drugs/DB00244
Ref V. SPC text for Colacid at Fass.se, assessed as of March 2019.