GenotoxicityAcceptedBeyond the letter
Prodrug tebipenem pivoxil positive in vitro (mammalian gene mutation, CHO chromosomal aberration); in vivo micronucleus negative
Why: Totality of evidence; rapid gut conversion of the prodrug to the non-mutagenic active moiety · Weight of evidence · Pharmacology or kinetics
“The prodrug, tebipenem pivoxil was found to be mutagenic in a mammalian cell gene mutation assay and induced chromosomal aberrations in Chinese hamster ovary (CHO) cells in vitro; however, it was not clastogenic in an in vivo bone marrow micronucleus study in mice.”
✓ VerifiedFDA integrated review, p. 212Source ↗ “Considering the totality of evidence and the evidence of rapid conversion of the prodrug tebipenem pivoxil in the gut to the non-mutagenic active moiety, tebipenem pivoxil is not considered to pose a meaningful mutagenic risk following oral administration.”
✓ VerifiedFDA integrated review, p. 213Source ↗ Impurity or metaboliteAccepted
Impurity with mutagenicity structural alerts specified above ICH M7 TTC-based limits
Why: TTC-based limits not practically achievable; oral route of administration · Within the guideline · Pharmacology or kinetics
“Chemistry, manufacturing, and controls (CMC) noted that ICH M7(R2) threshold of toxicological concern (TTC)-based limits are not practically achievable given observed batch levels up to %. Given the oral route of administration, the not more than (NMT) % limit was therefore acceptable from both CMC and pharmacology/toxicology perspectives but should be re-evaluated if the route of administration changes.”
✓ VerifiedFDA integrated review, p. 105Source ↗ GLPVerdict not stated
Clinical salt form tested only in 28-day GLP studies; longer (90-day) and juvenile studies with the prodrug were non-GLP
“Specifically, oral administration of the proposed clinical formulation, tebipenem pivoxil hydrobromide has been studied in rats and monkeys in repeat dose 28-day GLP toxicology studies, while tebipenem pivoxil has been studied in rats and monkeys in non-GLP studies (i.e. 14-day, 28-day, and 90-day studies).”
✓ VerifiedFDA integrated review, p. 211Source ↗ Safety marginVerdict not stated
13-week monkey NOAEL at 0.9 times the MRHD exposure
“and minimal cecal erosion in the 13-week monkey study (NOAEL 300 mg/kg/day; 0.9 times the MRHD based on exposure), consistent with the antibacterial class of drugs.”
✓ VerifiedFDA integrated review, p. 105Source ↗