National Toxicology Program

DEPARTMENT OF HEALTH AND HUMAN SERVICES
Public Health Service

National Toxicology Program (NTP); Availability of Technical Report on Toxicology and Carcinogenesis Studies of Methylphenidate Hydrochloride

The HHS' National Toxicology Program announces the availability of the NTP Technical Report on the toxicology and carcinogenesis studies of methylphenidate hydrochloride. Methylphenidate hydrochloride is a drug used in the treatment of narcolepsy and attention deficit hyperactivity disorders.

Toxicology and carcinogenicity studies were conducted by administration of methylphenidate hydrochloride in feed to groups of 70 F344/N rats of each sex at doses of 0, 100, 500, or 1,000 ppm and to groups of 70 B6C3F1 mice of each sex at doses of 0, 50, 250, or 500 ppm.

Under the conditions of these 2-year feed studies, there was no evidence of carcinogenic activity* of methylphenidate hydrochloride in male or female F344/N rats receiving 100, 500, or 1,000 ppm. There was some evidence of carcinogenic activity in male and female B6C3F1 mice, based on the occurrence of hepatocellular neoplasms.

Treatment of female rats with methylphenidate hydrochloride was associated with a decrease in the incidence of mammary gland fibroadenomas. Administration of methylphenidate hydrochloride to male and female mice resulted in increased incidence of eosinophilic foci in the liver.

Questions or comments about the Technical Report should be directed to Central Data Management at P.O. Box 12233, Research Triangle Park, NC 27709 or telephone (919) 541-3419.

Copies of Toxicology and Carcinogenesis Studies of Methylphenidate Hydrochloride (CAS No. 298-59-9) (TR-439) are available without charge from Central Data Management, NIEHS, MD E1-02, P.O. Box 12233, Research Triangle Park, NC 27709; telephone (919) 541­3419 or send e-mail to CDM@niehs.nih.gov.

Dated: March 27, 1996

 
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Kenneth Olden, Ph.D.
Director
National Toxicology Program

[Billing Code 4140-01]

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*The NTP uses five categories of evidence of carcinogenic activity observed in each animal study: two categories for positive results ("clear evidence" and "some evidence"), one category for uncertain findings ("equivocal evidence"), one category for no observable effect ("no evidence"), and one category for studies that cannot be evaluated because of major flaws ("inadequate study").