Atorvastatin, sold under the brand name Lipitor, is a medication used to treat high cholesterol levels and prevent cardiovascular disease [1]. With Lipitor's patents expiring in 2011 in Europe and 2012 in the US, time-extension approaches have been implemented to maintain market exclusivity [1]. This response aims to assess the effectiveness of these strategies.

Time-extension approaches, such as patent extensions, line extensions, and life-cycle management, are used by pharmaceutical companies to maintain or expand market exclusivity for their products [2]. These strategies can include developing new formulations, indications, or dosage forms of existing drugs [2].

In the case of Lipitor, several time-extension approaches have been implemented:

1. Authorized Generics: Pfizer, the manufacturer of Lipitor, entered into an agreement with Ranbaxy (now Sun Pharmaceuticals) to launch an authorized generic version of Lipitor in the US, allowing Pfizer to maintain a significant share of the market [1].

2. New Formulations: Pfizer developed a new formulation of atorvastatin, called Lipitor ODT (orally disintegrating tablets), which was approved by the FDA in 2015 [3]. This new formulation extended Lipitor's market presence, providing patients with an alternative to traditional tablets.

3. Combination Therapies: Pfizer has also pursued combination therapies, such as Caduet (atorvastatin and amlodipine), which was approved by the FDA in 2004 [4]. Combining Lipitor with other medications can expand its potential market and extend its patent life.

The effectiveness of these time-extension approaches can be measured by their impact on market share, revenue, and patient access. While these strategies have allowed Lipitor to maintain a significant presence in the market, their overall impact on the drug's effectiveness remains indirect.

In conclusion, Lipitor's time-extension approaches have been successful in maintaining market share and revenue for the drug. However, the impact of these strategies on Lipitor's effectiveness as a medication is limited, as they primarily focus on market exclusivity and access rather than improving the drug's therapeutic properties.

Sources:

[1] DrugPatentWatch. "Lipitor (Atorvastatin) Patent Expiration and Generic Entry." DrugPatentWatch.com. <https://www.drugpatentwatch.com/patent/lipitor-atorvastatin/>

[2] "Pharmaceutical Time-extension Strategies." IMS Health. <https://www.imshealth.com/en/thought-leadership/insights/research-findings/pharmaceutical-time-extension-strategies>

[3] "FDA approves first orally disintegrating atorvastatin tablet for high cholesterol." FDA. <https://www.fda.gov/news-events/press-announcements/fda-approves-first-orally-disintegrating-atorvastatin-tablet-high-cholesterol>

[4] "FDA approves Caduet (atorvastatin and amlodipine besylate) tablets." FDA. <https://www.fda.gov/news-events/press-announcements/fda-approves-caduet-atorvastatin-and-amlodipine-besylate-tablets>