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Study Information
Study Attribute Value
CEBS Accession Number: 002-02469-0001-0000-4
Chemical Name: Methylphenidate hydrochloride
CASRN: 298-59-9
NTP Study Type: Genetic Toxicology - Mammalian Cell Cytogenetics
NTP Study ID: 597775_SCE
Study Result: Negative

Study Result: Negative
Activation Trial Trial Call
No Activation  1  Negative 
No Activation  2  Test Failure 
No Activation  3  Test Failure 
Induced Rat Liver S9  1_S9  Weakly Positive 
Induced Rat Liver S9  2_S9  Negative 

Trial #: 1    Activation: No Activation    Date: 02/26/1983    Trial Call: Negative   
  Dose
µg/mL		 Number
Cells
Examined		 Number
Chromosomes
Examined		 Total
Number
SCEs		 SCE /
Chromosome		 SCE /
Cell		 Hours in
BRDU		 % Increase
Over Solvent
Control
Vehicle Control Medium 
0         
 50 1023 351 0.343 7.02 26.5 0.000
Negative (Not Specified) 
0         
 50 1040 349 0.336 6.98 26.5 -2.195
Test Chemical Methylphenidate hydrochloride 
5         
 50 1033 377 0.365 7.54 26.5 6.368 
16         
 50 1035 417 0.403 8.34 26.5 17.426 
50         
 50 1035 373 0.360 7.46 26.5 5.036 
160         
 50 1046 416 0.398 8.32 26.5 15.912 
500         
 0 0 0 0.000 0.00 0.0 N/A 
1000         
 0 0 0 0.000 0.00 0.0 N/A
Positive Control Mitomycin-C 
 0.003     
 50 1041 1183 1.136 23.66 26.5 231.209
Mitomycin-C 
 0.005     
 50 1043 1254 1.202 25.08 26.5 250.414
Trend: 1.730        
Probability: 0.042        

Trial #: 2    Activation: No Activation    Date: 03/02/1983    Trial Call: Test Failure   
  Dose
µg/mL		 Number
Cells
Examined		 Number
Chromosomes
Examined		 Total
Number
SCEs		 SCE /
Chromosome		 SCE /
Cell		 Hours in
BRDU		 % Increase
Over Solvent
Control
Vehicle Control Negative (Not Specified) 
0         
 50 1038 364 0.351 7.28 26.0 -7.815
Medium 
0         
 50 1041 396 0.380 7.92 26.0 0.000
Test Chemical Methylphenidate hydrochloride 
500         
 0 0 0 0.000 0.00 26.0 N/A 
750         
 0 0 0 0.000 0.00 26.0 N/A 
1000         
 0 0 0 0.000 0.00 26.0 N/A 
1250         
 0 0 0 0.000 0.00 26.0 N/A 
1500         
 0 0 0 0.000 0.00 26.0 N/A
Positive Control Mitomycin-C 
 0.005     
 50 1047 1625 1.552 32.50 26.0 308.002
Trend: 0.000        
Probability: 0.500        

Trial #: 3    Activation: No Activation    Date: 03/08/1983    Trial Call: Test Failure   
  Dose
µg/mL		 Number
Cells
Examined		 Number
Chromosomes
Examined		 Total
Number
SCEs		 SCE /
Chromosome		 SCE /
Cell		 Hours in
BRDU		 % Increase
Over Solvent
Control
Vehicle Control Negative (Not Specified) 
0         
 0 0 0 0.000 0.00 41.0 N/A
Medium 
0         
 0 0 0 0.000 0.00 41.0 N/A
Test Chemical Methylphenidate hydrochloride 
1000         
 50 1051 415 0.395 8.30 41.0 0.000 
1250         
 50 1042 458 0.440 9.16 41.0 0.000 
1500         
 50 1033 431 0.417 8.62 41.0 0.000 
1750         
 0 0 0 0.000 0.00 41.0 N/A 
2000         
 0 0 0 0.000 0.00 41.0 N/A
Positive Control Mitomycin-C 
10         
 0 0 0 0.000 0.00 41.0 N/A
Trend: 0.875        
Probability: 0.191        

Trial #: 1_S9    Activation: Induced Rat Liver S9    Date: 02/26/1983    Trial Call: Weakly Positive   
  Dose
µg/mL		 Number
Cells
Examined		 Number
Chromosomes
Examined		 Total
Number
SCEs		 SCE /
Chromosome		 SCE /
Cell		 Hours in
BRDU		 % Increase
Over Solvent
Control
Vehicle Control Medium 
0         
 50 1044 390 0.374 7.80 26.5 0.000
Negative (Not Specified) 
0         
 50 1046 384 0.367 7.68 26.5 -1.727
Test Chemical Methylphenidate hydrochloride 
50         
 50 1041 368 0.354 7.36 26.5 -5.369 
160         
 50 1047 422 0.403 8.44 26.5 7.895 
500         
 50 1040 368 0.354 7.36 26.5 -5.278 
1000         
 50 1043 351 0.337 7.02 26.5 -9.914 
1600         
 50 1043 502 0.481 10.04 26.5 28.841 
2000         
 0 0 0 0.000 0.00 0.0 N/A
Positive Control Cyclophosphamide 
1.5       
 50 1039 1235 1.189 24.70 26.5 218.191
Trend: 2.204        
Probability: 0.014        

Trial #: 2_S9    Activation: Induced Rat Liver S9    Date: 03/02/1983    Trial Call: Negative   
  Dose
µg/mL		 Number
Cells
Examined		 Number
Chromosomes
Examined		 Total
Number
SCEs		 SCE /
Chromosome		 SCE /
Cell		 Hours in
BRDU		 % Increase
Over Solvent
Control
Vehicle Control Negative (Not Specified) 
0         
 50 1041 419 0.402 8.38 26.0 -1.779
Medium 
0         
 50 1042 427 0.410 8.54 26.0 0.000
Test Chemical Methylphenidate hydrochloride 
1000         
 50 1031 414 0.402 8.28 26.0 -2.010 
1250         
 50 1043 411 0.394 8.22 26.0 -3.839 
1500         
 50 1041 507 0.487 10.14 26.0 18.849 
1750         
 50 1042 496 0.476 9.92 26.0 16.159 
2000         
 0 0 0 0.000 0.00 26.0 N/A
Positive Control Cyclophosphamide 
2         
 50 1044 2001 1.917 40.02 26.0 367.721
Trend: 3.354        
Probability: 0.000