Following the recall of Pfizer’s smoking cessation drug Chantix in 2021, Endo’s subsidiary Par Pharmaceuticals has stood as the sole marketer of the product. However, Par Pharmaceuticals is now facing off against other generic manufacturers seeking a piece of the action, resulting in a lawsuit that sheds light on patent disputes and manufacturing techniques.
Endo’s legal action asserts that Zydus introduced its generic version of Chantix, which gained FDA approval in June, after being made aware of a new patent by Endo. The alleged infringement occurred before Endo could file a patent infringement claim. This new patent focuses on the innovative manufacturing method employed by Endo, which ensures the production of the drug without the impurities that led to the downfall of Pfizer’s original Chantix product.
When Chantix was initially approved in 2006, it experienced a successful run with peak sales reaching $1.1 billion. However, the discovery of impurities within the product resulted in its abrupt decline. Pfizer’s decision to recall all Chantix lots in September 2021 prompted the FDA to exclusively consider submissions for products based on Chantix’s active ingredient, varenicline tartrate, that met the acceptable intake limit for nitrosamine impurities. Endo was able to meet these stringent requirements, a feat that eluded Pfizer and other competitors.
Endo’s lawsuit highlights the intricate challenge of producing varenicline tartrate tablets with the low levels of nitrosamine mandated by the FDA. Despite the considerable incentive, Pfizer struggled to reformulate its Chantix product to meet these standards, as mentioned in the complaint.
Endo’s contention is that Zydus utilized the methodologies outlined in its recently obtained patent because they represent the sole commercially viable methods for achieving the desired low levels of nitrosamine impurities. The suit alleges that Zydus launched its generic version without engaging with the notices sent by Endo, leaving the latter unable to ascertain if both companies adopted the same manufacturing techniques. Despite this uncertainty, Endo considers it highly plausible.
Financial challenges further underscore Endo’s position. After filing for bankruptcy in August, the company faced the weight of substantial opioid-related settlements and an $8 billion debt burden. The original plan involved Endo’s sale to its senior lender group, a move aimed at funding the company’s opioid settlements. However, this strategy faced opposition from the US. Department of Justice, which deemed it a violation of bankruptcy law due to its unequal treatment of creditors, as reported by Reuters.
As the legal dispute unfolds, the dynamics of patent protection, manufacturing methodologies, and financial struggles converge in a complex battle over the future of Chantix’s generic market.
