The Association for Accessible Medicines (AAM) objects to the higher impurity threshold limits set in the US Food and Drug Administration’s (FDA) revised draft guidance on quality considerations for topical ophthalmic drugs and said that failure to align these limits with the International Council on Harmonisation’s Q3B(R2) guideline could jeopardize the development of these products.
The agency received a total of 18 comments on the revised guidance published in December 2023, with many of the comments addressing the guidance’s impurity testing provisions.
The guidance was revised from an October 2023 version to clarify that drugs compounded by outsourcing facilities under section 503B of the Federal Food, Drug, and Cosmetic (FD&C) Act, and also adds microbiological studies to the battery of tests manufacturers should perform to assess the quality of topical ophthalmic products.
The guidance was prompted by consumer injuries and deaths from microbially contaminated ophthalmic drug products as well as recent recalls. The guidance recommends that manufacturers follow certain microbial testing guidelines to ensure that products remain sterile throughout the drug’s shelf life.
Guidance does not align with ICH’s threshold limits
AAM urged FDA to align its impurity limits to those set in the ICH Q3B(R2) guideline. The FDA guidance sets a impurity limit of 0.1% for drug products while the ICH Q3B (R2) guideline sets a higher 0.5% impurity limit for drug products in the 10 mg to 100 mg maximum daily dose (MDD) range.
The Q3B(R2) guideline, which was adopted in June 2006, provides information to sponsors on the content and qualification of impurities in new drug products produced from chemically synthesized new drug substances not previously registered in a region or member state.
AAM said its members are “concerned that the draft guidance establishes qualification thresholds (“QT”) for individual unspecified degradation products or impurities that are significantly lower than the thresholds in the Guidance for Industry Q3B(R2) Impurities in New Drug Products.”
The group further argues that the threshold is not “scientifically justified” and if adopted “will make development of ophthalmic products more costly.”
Alcon also urged FDA to align the guidance with the ICH Q3B(R2) document. The company said the “recommended Identification and Qualification Threshold of 0.1% of API impurity/degradation product of products with active concentration between 0.1% and 1% is quite stringent.”
AAM objects to additional safety testing
AAM also took issue with the provision recommending that sponsors provide safety information for unspecified degradation products or impurities which exceed the recommended threshold and provide this information in the application.
The group said that “relevant toxicological information may not be available in the scientific literature, and, consequently, an applicant would need to decide whether to invest in toxicological studies on animals to generate the missing information. Such testing is expensive, time-consuming, and ethically questionable given the desire to phase out animal testing.”
The group added that “adoption of such unnecessarily rigorous requires regarding impurity levels would be harmful to pains because the costs pf testing may be so high that applicants choose not to do the testing and will not supply these drugs.”
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