title: A rationale for determining, testing, and controlling specific impurities in pharmaceuticals that possess potential for genotoxicity.
abstract: The synthesis of pharmaceutical products frequently involves the use of reactive reagents and the formation of intermediates and by-products. Low levels of some of these may be present in the final drug substance and drug product as impurities. Such chemically reactive impurities may have at the same time the potential for unwanted toxicities including genotoxicity and carcinogenicity and hence can have an impact on product risk assessment. This paper outlines a procedure for testing, classification, qualification, toxicological risk assessment, and control of impurities possessing genotoxic potential in pharmaceutical products. Referencing accepted principles of cancer risk assessment, this document proposes a staged threshold of toxicological concern (TTC) approach for the intake of genotoxic impurities over various periods of exposure. This staged TTC is based on knowledge about tumorigenic potency of a wide range of genotoxic carcinogens and can be used for genotoxic compounds, for which cancer data are limited or not available. The delineated acceptable daily intake values of between approximately 1.5 microg/day for approximately lifetime intake and approximately 120 microg/day for < or = 1 month are virtually safe doses. Based on sound scientific reasoning, these virtually safe intake values do not pose an unacceptable risk to either human volunteers or patients at any stage of clinical development and marketing of a pharmaceutical product. The intake levels are estimated to give an excess cancer risk of 1 in 100,000 to 1 in a million over a lifetime, and are extremely conservative given the current lifetime cancer risk in the population of over 1 in 4 (http://seer.cancer.gov/statfacts/html.all.html). The proposals in this document apply to all clinical routes of administration and to compounds at all stages of clinical development. It is important to note that certain types of products, such as those for life-threatening indications for which there are no safer alternatives, allow for special considerations using adaptations of the principles outlined in this paper.
authors.affiliation: Hoffmann-La Roche, PRBN-T, Bldg. 73/311B, CH-4070, Basel, Switzerland. Lutz.Mueller@roche.com
authors.forename: Lutz
authors.initials: L
authors.lastname: Müller
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Mauthe
authors.forename: Christopher M
authors.initials: CM
authors.lastname: Riley
authors.forename: Marta M
authors.initials: MM
authors.lastname: Andino
authors.forename: David De
authors.initials: DD
authors.lastname: Antonis
authors.forename: Chris
authors.initials: C
authors.lastname: Beels
authors.forename: Joseph
authors.initials: J
authors.lastname: DeGeorge
authors.forename: Alfons G M
authors.initials: AG
authors.lastname: De Knaep
authors.forename: Dean
authors.initials: D
authors.lastname: Ellison
authors.forename: Jane A
authors.initials: JA
authors.lastname: Fagerland
authors.forename: Rebecca
authors.initials: R
authors.lastname: Frank
authors.forename: Betsy
authors.initials: B
authors.lastname: Fritschel
authors.forename: Sheila
authors.initials: S
authors.lastname: Galloway
authors.forename: Ernie
authors.initials: E
authors.lastname: Harpur
authors.forename: Charles D N
authors.initials: CD
authors.lastname: Humfrey
authors.forename: Alexander S
authors.initials: AS
authors.lastname: Jacks
authors.forename: Nirdosh
authors.initials: N
authors.lastname: Jagota
authors.forename: John
authors.initials: J
authors.lastname: Mackinnon
authors.forename: Ganapathy
authors.initials: G
authors.lastname: Mohan
authors.forename: Daniel K
authors.initials: DK
authors.lastname: Ness
authors.forename: Michael R
authors.initials: MR
authors.lastname: O'Donovan
authors.forename: Mark D
authors.initials: MD
authors.lastname: Smith
authors.forename: Gopi
authors.initials: G
authors.lastname: Vudathala
authors.forename: Larry
authors.initials: L
authors.lastname: Yotti
mesh_terms: D000818:Animals; D002273:Carcinogens / Q000032:analysis / Q000737:chemistry / Q000145:classification; D004340:Drug Contamination / Q000517:prevention & control*; D017408:Guidelines as Topic; D006801:Humans; D009153:Mutagens / Q000032:analysis* / Q000737:chemistry / Q000145:classification; D004364:Pharmaceutical Preparations / Q000138:chemical synthesis*; D018570:Risk Assessment / Q000379:methods; D013329:Structure-Activity Relationship
chemical_list: D002273:Carcinogens; D009153:Mutagens; D004364:Pharmaceutical Preparations