US FDA guidance for industry April – June 2026

DateTitle of guidance and link to documentType and level
of guidance
About the guidance
17 Apr 2026Establishing Impurity Specifications for AntibioticsDraft, Level 1This guidance provides recommendations to industry for establishing specifications for impurities in antibiotics manufactured by fermentation and semi-synthesis. These recommendations can be used to establish consistent standards for impurity testing and ensure that batches of antibiotic drug products meet appropriate impurity specifications. This guidance applies to antibiotic drugs, including:

• Antibiotic drugs subject to approval under new drug applications (NDAs) and abbreviated new drug applications (ANDAs) submitted under section 505 of the Federal FD&C Act (21 U.S.C. 355) and associated type II drug substance drug master files (DMFs) referenced in NDAs and ANDAs for antibiotic products

• Nonprescription antibiotic drugs marketed under section 505G of the FD&C Act, often referred to as over the-counter (OTC) monograph drugs.
10 Apr 2026Bioanalytical Method Validation for BiomarkersFinal, Level 2This guidance helps sponsors of INDs and applicants of NDAs, BLAs, and NDA and BLA supplements as well as ANDAs, as applicable, to validate bioanalytical methods used to evaluate biomarker concentrations. This guidance can also
inform the development of bioanalytical methods used for the analysis of biomarker concentrations in nonclinical study samples.

The recommendations in this guidance pertain only to the validation of bioanalytical assays to measure in vivo biomarker concentrations in biological matrices such as blood or urine. This guidance does not apply to bioanalytical method validations for the measurement of veterinary drug concentrations or veterinary biomarker concentrations.