Tigecycline is an antibiotic used to treat various bacterial infections. In terms of patent extensions, it is essential to consider the regulations and limitations surrounding them. The U.S. Patent and Trademark Office (USPTO) provides guidelines for patent term extensions under 35 U.S.C. 156, which allows for extensions in certain circumstances, such as delays in obtaining regulatory approval. These extensions are subject to specific criteria and limitations outlined by the USPTO [2].

When examining the patent status of Tigecycline, it is crucial to refer to resources like Drug Patent Watch, which can provide insights into the patent landscape of pharmaceutical products. Understanding the patent status of Tigecycline can offer valuable information on any extensions or restrictions that may apply to its patent protection [1].

Additionally, scholarly articles, such as the one from the National Center for Biotechnology Information (NCBI), can provide in-depth analysis and discussions on patent extensions and related topics. These sources can offer a more comprehensive understanding of the legal and regulatory framework governing patent extensions for pharmaceutical products like Tigecycline [3].

In conclusion, to determine if there are any restrictions on the patent extension of Tigecycline injection, one should consult the USPTO guidelines, resources like Drug Patent Watch, and scholarly articles like the one from NCBI for a comprehensive understanding of the patent landscape and regulatory framework surrounding Tigecycline's patent extension [1][2][3].

Sources:
[1] https://www.drugpatentwatch.com/p/tradename/TIGECYCLINE
[2] https://www.uspto.gov/patents/laws/patent-term-extension/patent-terms-extended-under-35-usc-156
[3] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4037176/