On May 2022, the FDA published a new batch of product-specific guidances (PSGs). PSGs provide recommendations for developing generic drugs and generating the evidence needed to support abbreviated new drug application (ANDA) approval, helping to streamline generic product development and ANDA assessment.


To successfully develop and manufacture a generic drug product, an applicant should consider that their product is expected to be: pharmaceutically equivalent to its reference listed drug (RLD), i.e., to have the same active ingredient, dosage form, strength, and route of administration under the same conditions of use; bioequivalent to the RLD, i.e., to show no significant difference in the rate and extent of absorption of the active pharmaceutical ingredient; and, consequently, therapeutically equivalent, i.e., to be substitutable for the RLD with the expectation that the generic product will have the same safety and efficacy as its reference listed drug.

Important information about the generic drug

Different types of tests can be used to establish bioequivalence for equivalent pharmaceutical products such as:

  • In vivo tests
  • In vitro tests
  • Both tests

The selection of the method used to demonstrate bioequivalence depends on the purpose of the study, the analytical methods available, and the nature of the pharmaceutical product.

Under this regulation, applicants must perform bioequivalence testing using the most accurate, sensitive, and reproducible approach available among those provided in 21 CFR 320.24.

batch of 37 PSGs includes:

• 24 new and 13 revised PSGs
• 14 PSGs for complex products (11 new and 3 revised PSGs); 9 of these for products with no approved ANDAs (8 new PSGs)
• 26 PSGs for products with no approved ANDAs (18 non-complex and 8 complex products)

Generic Drug User Fee (GDUFA) science and research, such as:

Diabetes – FDA developed two PSGs for exenatide subcutaneous suspension (RLDs: Bydureon, NDAs 022200 and 209210), which recommend, for the first time, two selective in vivo pharmacokinetic bioequivalence (BE) study options. The two options were developed after evaluation of the pros and cons of each study design, including but not limited to, detection limit of bioanalytical method, data variability, study duration, and sample size. Applicants may utilize either of these two study designs for generic product development.

Breast Cancer – Palbociclib tablet (RLD: IBRANCE, NDA 212436) is a kinase inhibitor indicated for the treatment of adult patients with hormone receptor-positive, human epidermal growth factor receptor 2-negative advanced or metastatic breast cancer. Because the pharmacokinetics of palbociclib can be altered in the presence of an acid-reducing agent, such as a proton pump inhibitor (PPI), and such impact is formulation-dependent, in addition to BE studies under fasting and fed conditions, an in vivo fasting BE study with a PPI is recommended to ensure BE between the generic product and the RLD in subjects who are taking PPIs.

Adult Periodontitis – Chlorhexidine gluconate tablet (RLD: Periochip, NDA 020774) is a biodegradable chip which is indicated as an adjunct to scaling and root planing procedures for reduction of pocket depth in patients with adult periodontitis. The new PSG includes two options to support a BE demonstration: an in vitro totality-of-evidence approach and a comparative clinical endpoint BE study option.

Newly Updated – Upcoming Complex PSGs

The FDA also updated the Upcoming Product-Specific Guidances for Complex Generic Drug Product Development web page, which provides information about the agency’s plans for issuing new or revised PSGs in the coming year for complex generic drug products as defined in the GDUFA II Commitment Letter. This page is updated each time FDA publishes a new batch of PSGs.
For more information, to view the guidances, or to submit comments on the PSGs, visit the Federal Register Notice: Product-Specific Guidances.

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