OtherCriticised but acceptedBeyond the letter
No adequate general toxicology study: rat study with diluted product did not reach doses that explore taurolidine toxicity
Why: Previous clinical experience with taurolidine in catheter lock solutions judged adequate by medical reviewers · Human data
“A rat study conducted with a diluted solution of Defencath did not use high enough levels of the active ingredients to adequately explore the toxicity of taurolidine and identify possible target organs of toxicity (if any).”
✓ VerifiedFDA multi-discipline review, p. 41Source ↗ “However, the medical reviewers found that previous clinical experience with taurolidine (particularly as a component of CLS) was adequate to support the clinical development of Defencath and the toxicology reviewer deferred to their judgement.”
✓ VerifiedFDA multi-discipline review, p. 41Source ↗ DARTAcceptedBeyond the letter
Reproductive toxicity studies for taurolidine waived
Why: Product not intended for systemic administration · Pharmacology or kinetics
“Defencath is not intended for systemic administration, so the Division agreed to waive reproduction toxicity studies for taurolidine and deemed that these data were not needed for labeling.”
✓ VerifiedFDA multi-discipline review, p. 41Source ↗ CarcinogenicityAcceptedBeyond the letter
No carcinogenicity studies
Why: Not for systemic administration; negligible clinical exposure · Pharmacology or kinetics
“Carcinogenicity Carcinogenicity studies were not needed for Defencath because the product is not intended for systemic administration and clinical exposure to its components is negligible when used as directed.”
✓ VerifiedFDA multi-discipline review, p. 46Source ↗ GenotoxicityAcceptedBeyond the letter
Taurolidine positive in vitro (Ames and mouse lymphoma) but negative in vivo; accepted
Why: Negative in vivo; risk low at clinically achievable taurolidine exposure · Weight of evidence · Pharmacology or kinetics
“Although taurolidine is positive for genotoxicity in vitro regardless of metabolic activation (mouse lymphoma and Ames tests), it is negative in vivo.”
✓ VerifiedFDA multi-discipline review, p. 41Source ↗ “At the levels where taurolidine exposure could be achieved in the clinic during use of the Defencath CLS, the risk of genotoxicity appears low.”
✓ VerifiedFDA multi-discipline review, p. 41Source ↗