Disodium 3,3'-dithiobis[propanesulphonate]

Toxicity to reproduction: other studies

Administrative data

Endpoint:

toxicity to reproduction: other studies

Type of information:

read-across based on grouping of substances (category approach)

Adequacy of study:

supporting study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: acceptable well-documented publication which meets basic scientific principles

Justification for type of information:

REPORTING FORMAT FOR THE CATEGORY APPROACH
For details, please refer to the attached read-across justification. In brief:

1. HYPOTHESIS FOR THE CATEGORY APPROACH (ENDPOINT LEVEL)
There are two category approaches relevant for all human health associated endpoints: Chain-length category and similar metabolic pathway.
Chain-length Category: Both SPS and Dimesna are sodium salts of two sulphonated alkanes connected via a disulphide group. SPS contains two propane moieties, Dimesna ethane ones, hence, these chemicals only differ minor in their hydrocarbon chains in one –CH2– group. The same applies to the carbon chain in MPS and MESNA, connecting the sodium sulfonate with the sulfhydryl moiety. The reactivity and toxicological relevance of this difference in chain length is considered to be minor compared to the chemicals properties triggered by the two remaining respective functional groups. Comparing the actually available information on the substances with regard to their physico-chemical properties, the minor influence of the hydrocarbon chain length becomes obvious. The melting points for the disulphide compounds and the sulfhydryl ones are consistent, and the ones for the ethane derivatives are as expected slightly lower. All compounds are very soluble in water, and similar consistencies are noted with regard to vapour pressure and partition coefficient.
Metabolic pathway: Here it is aimed to justify the read-across from both MPS to SPS and Mensa to Dimesna, and Dimesna to SPS and Mesna to MPS (and vice versa) based on the available information on their metabolism.
Generally, Mesna and Dimesna are considered to be a metabolite of each other. Also, other metabolites of Mesna were identified, besides Mesna-Mesna (i.e., Dimesna), such as Mesna-Cys, Mesna-homocysteine, Mesna-cysteinylglutamate, Mesna-cysteinylglycine, and Mesna-GSH which have been collectively termed “Dimesna” in some studies, while others refer to the mixed disulfides containing a single Mesna moiety as “Mesna”, quantifying Dimesna separately. The relevant functional groups for the enzymatic and non-enzymatic metabolism of Dimesna and Mesna are the disulphide resp. thiol functional groups. Those are both contained in the related substances SPS and MPS, which only differ from the former in their hydrocarbon chains in one –CH2– group, the basic structure and functional groups are however identical. Hence, only taking into account the given functional groups, a similar toxicodynamic behaviour of SPS and MPS compared to Dimesna and Mesna can be expected.

2. CATEGORY APPROACH JUSTIFICATION (ENDPOINT LEVEL)
As shown above, Mesna, MPS, Dimesna and SPS can be used for read-across to each other by grouping of chemicals. Mesna and MPS and Dimesna and SPS share similar physico-chemical properties as well as they exhibit similar toxicological properties, where data is available. Their alkyl side chains differ only in one –CH2- group, so it can be concluded that e.g. absorption, distribution patterns, or excretion from organ systems and body are comparable. Furthermore, Dimesna and Mesna are considered a metabolite of each other, which allows the conclusion that the same also applies for SPS and MPS. Conclusively, data for Mesna, MPS, and Dimesna can be used to cover data gaps for SPS; especially for the required endpoints for human health assessment.
Freely available toxicological information on Dimesna is lacking, so the available information on SPS, MPS and Mesna will be compared in order to obtain contributing information for the read-across justification, as set out in the attachment
The available data indicate that SPS, MPS and Mesna do not need to be classified as acute toxic according to Regulation (EC) No 1272/2008, all available LD50 (oral or dermal) values are greater than 2000 mg/kg bw, clearly indicating the comparability of the substances and the relative harmlessness of all group members including the target chemical SPS with regard to acute toxicity.
All available Ames tests on SPS, MPS and Mesna are consistently negative. Furthermore, the available in vitro micronucleus test on MPS, the SCE assay and in vivo micronucleus test on Mesna do also not give any indication that this group of substances bears any genotoxic properties. Here, gene mutation as well as chromosome mutation and clastogenicity endpoints are covered. In addition, the SCE assay is indicative for an enhanced repair activity upon genotoxic damage, which may result in several outcomes, e.g. point mutations, chromosome breaks etc., which support additionally the hypothesis that this group does not bear genotoxic properties of any kind.
In the available publications on carcinogenicity, both Mesna and its dimer Dimesna did not trigger any signs of toxicity or carcinogenic activity up to the highest dose tested, i.e., 15 resp. 35 mg/kg bw/d with lifetime exposure. Data on Mesna alone indicate that both doses could have been chosen much higher without resulting in any effects, as e.g. a NOAEL was determined to be 350 mg/kg bw/d over an exposure period of 39 weeks. Again this indicates that this group of chemicals does not trigger any relevant adverse effects upon repeated dosage. Last but not least, Mesna was not identified to be a developmental and or reproductive toxicant in several available studies on that endpoint, up to and including limit dosages of 2000 mg/kg bw/d.

Data source

Reference

Reference Type:

publication

Title:

Effects of subchronic ifosfamide-mesna treatment on testes and semen characteristics in the rabbit

Author:

Ypsilantis, P., Papaioannou, N., Dimitra Psalla, D., Politou, M., Pitiakoudis, M., Simopoulos, C.

Year:

2003

Bibliographic source:

Reproductive Toxicology 17 (2003) 699-708

Materials and methods

Test guideline

Qualifier:

no guideline followed

Principles of method if other than guideline:

Sexually mature New Zealand White male rabbits received intravenously 10 weekly treatments of ifosfamide + mesna (groups A, B and C received 30, 45 or 60 mg/kg of body weight ifosfamide + 6, 9 or 12 mg/kg of body weight mesna, respectively, followed by a second equal dose of mesna 4 h later); groups MA, MB and MC received mesna alone at corresponding doses; and group S received normal saline. Reproductive organ weight as well as various qualitative and quantitative parameters of testis histology were determined 1 day and 20 weeks after the treatment period, while semen quality and libido were evaluated on a weekly basis.

GLP compliance:

no

Type of method:

in vivo

Test material

Test material information

Constituent 1

Reference substance name:

Disodium 3,3'-dithiobis[propanesulphonate]

EC Number:

248-324-3

EC Name:

Disodium 3,3'-dithiobis[propanesulphonate]

Cas Number:

27206-35-5

Molecular formula:

C6H14O6S4.2Na

IUPAC Name:

disodium 3,3'-disulfanediyldipropane-1-sulfonate

Test material form:

solid

Test animals

Species:

rabbit

Strain:

New Zealand White

Sex:

male

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source:
- Age at study initiation: (P) x 6 months
- Weight at study initiation: (P) Males: 3.6-4.0 kg
- Fasting period before study: no
- Housing: the rabbits were housed individually in wire cages
- Diet (e.g. ad libitum): ad libitum (125 g commercial pelleted diet (certified rabbit chow, #51/ EL.VI.Z, Xanthi, Greece) per day)
- Water (e.g. ad libitum): ad libitum
- Acclimation period: 3 weeks
The facilities were in accordance to the Directive 86/609/EEC.

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 20-22
- Photoperiod (hrs dark / hrs light): 12/12

Administration / exposure

Route of administration:

intravenous

Vehicle:

physiological saline

Details on exposure:

PREPARATION OF DOSING SOLUTIONS: Mesna (Uromitexan sol 10%; Asta Medica AG, Frankfurt, Germany) was provided at a 10% solution. For the mesna-alone solution, mesna was diluted in normal saline up to a volume of 25 mL and administered intravenously at a rate of 2.5 mL/min.

VEHICLE
- Justification for use and choice of vehicle (if other than water): phisiological saline is used in standard procedure of mesna administration by i.v. route.

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

The animals were weighed at a weekly basis to accurately determine the doses administered.

Duration of treatment / exposure:

9 weeks (10 treatments)

Frequency of treatment:

Once a week

Duration of test:

First phase: 9 weeks (direct effects);
Second phase: 20 weeks after the last treatment (recovery effects).

Doses / concentrations

Remarks:

Doses / Concentrations:
6, 9, and 12 mg/kg bw (first and second treatments)
Basis:
other: Mesna was given at a dose equal to 40% of the ifosfamide dose, divided into two equivalent doses.

No. of animals per sex per dose:

10

Control animals:

yes, concurrent vehicle

Details on study design:

The animals were trained for semen donation using an artificial vagina and a teaser doe. Weekly samples were collected for 3 weeks prior to treatment to assure that males had normal libido and semen quality. Each male ejaculated four times in 1 day with a 20-30 min interval between ejaculations.

Statistics:

The SPSS/PC+™ V. 6.1 software package was used for data analysis. Values were expressed as means ± standard deviation (S.D.). Shapiro-Wilks test was used to examine the normality of the data. One-way analysis of variance (ANOVA), followed by Duncan's multiple range post-test for multiple pairwise comparisons, was used to assess differences across several independent groups of animals (regarding reproductive organ weights and histological findings). Analysis of variance for repeated measures followed by Student's Test was used to evaluate differences between variables in serial measures (regarding sperm characteristics). An alpha probability of less than 5% (P < 0.05) was considered to be statistically significant.

Results and discussion

Effect levels

Dose descriptor:

dose level:

Effect level:

18 other: mg/kg bw/week (infused as 9 mg/kg bw two times 4-h apart)

Based on:

other: i.v. solution

Sex:

male

Basis for effect level:

other: No effects

Observed effects

No changes were noted in reproductive organ weights in the mesna groups. No gross histopathological testicular lesions were observed. Quantitative testicular histological examinations (minor diameter of seminiferous tubules, the most advanced germ cell type in seminiferous tubule identified in cross sections, and the number of germ cells per stage 1 seminiferous tubule cross section) revealed no significant changes in the mesna groups compared to controls. No changes regarding sperm characteristics (sperm count, sperm morphology, and sperm progressive motility) were noted in the mesna groups.

Applicant's summary and conclusion

Conclusions:

Mesna did not induce any pathological alteration in reproductive organ weights, quantitative and qualitative parameters of testis histology as well as in semen quality.

Executive summary:

Ifosfamide, a chemotherapeutic agent with a broad spectrum of antineoplastic activity, is concurrently administered with the uroprotectant mesna to avoid the urotoxic effect. This study was undertaken to investigate possible effects of ifosfamide-mesna treatment on the testes and semen characteristics in rabbits. Sexually mature New Zealand White male rabbits received intravenously 10 weekly treatments of ifosfamide + mesna (groups A, B and C received 30, 45 or 60 mg/kg of body weight ifosfamide + 6, 9 or 12 mg/kg of body weight mesna, respectively, followed by a second equal dose of mesna 4 h later); groups MA, MB and MC received mesna alone at the corresponding doses; and group S received normal saline. Reproductive organ weight as well as various qualitative and quantitative parameters of testis histology (minor diameter of seminiferous tubules, the most advanced germ cell type in seminiferous tubule identified in cross sections, and the number of germ cells per stage 1 seminiferous tubule cross section) were determined 1 day and 20 weeks after the treatment period, while semen quality (sperm count, sperm morphology and sperm progressive motility) and libido were evaluated on a weekly basis.

Changes were noted only in the ifosfamide - mesna treated animals. One day after treatment, reproductive organ weights were decreased in groups A-C. Major histopathological lesions were not found; however, quantitative histological endpoints were altered in groups A-C. Transient oligospermia and teratozoospermia were noted in groups B and C, while asthenozoospermia was observed in group C only. The time course of these sperm alterations suggested possible bioaccumulation and residual activity of ifosfamide. Libido remained normal. The decrease in reproductive organ weights persisted in groups B and C to 20 weeks after treatment but only one quantitative histological endpoint, the number of the round spermatids per stage 1 seminiferous tubule cross section, remained decreased in group C. These results suggest that subchronic treatment with ifosfamide-mesna suppressed spermatogenesis and epididymal sperm maturation in the rabbit. Germinal epithelium recovery was not complete because although sperm characteristics returned to pretreatment values, not all histological alterations were ameliorated.

No treatment related changes in any parameter tested were noted in the mesna-alone groups. Reproductive organ weights (testes, epididymides and accessory glands) were comparable to control. No gross histopathological lesions were observed. Quantitative testicular histological examinations revealed no significant changes in the mesna groups compared to controls. Sperm characteristics remained unaffected in the mesna groups.

Mesna is a suitable Read-Across substance for SPS as Dimesna and Mesna could be considered a metabolite of each other, which allows the conclusion that the same also applies for SPS and MPS, and their respective alkyl side chains differ only in one –CH₂- group. This is in detail outlined in the read-across justification. Hence, it can be concluded that the derived results are applicable for SPS, too.