Pfizer Halts Development of Twice-Daily Weight Loss Pill Due to Adverse Effects


Pfizer announced it will discontinue the twice-daily version of its weight loss pill due to high rates of adverse side effects observed in a mid-stage clinical study, impacting the company’s hopes of capturing a share in the booming weight loss drug market.

Pfizer’s Decision to Halt the Twice-Daily Weight Loss Pill

Pfizer has decided to discontinue the development of the twice-daily version of its experimental weight loss pill following a mid-stage clinical study which revealed that while obese patients taking the drug experienced weight loss, they encountered difficulties in tolerating it.

High Rates of Adverse Side Effects and Impact on Pfizer’s Plans

The drugmaker observed high rates of adverse side effects, mostly mild and gastrointestinal, among patients. This resulted in a significant number of patients discontinuing the drug during the trial. This decision has impacted Pfizer’s ambition to secure a $10 billion portion of the rapidly expanding weight loss drug market, which CEO Albert Bourla had anticipated to grow to $90 billion.

Future Plans for Once-Daily Version and Competitive Landscape

While Pfizer still plans to release phase two trial data on a once-a-day version of the drug in 2024, the company is now facing heightened competition in the weight loss drug market. The discontinuation of the twice-daily pill has placed Pfizer further behind established players in the market such as Eli Lilly and Novo Nordisk, who are progressing with the development of more convenient pill versions of their successful weight loss and diabetes injections.

Impact on Patients and Market Potential

The realization of adverse side effects among patients in the trial has raised concerns about the drug’s impact on the weight loss market. Pfizer’s phase two trial, involving 600 obese adults without Type 2 diabetes, demonstrated significant reductions in body weight across different dosage amounts. However, high rates of adverse events were observed, with a notable portion of patients experiencing nausea, vomiting, and diarrhea, leading to a majority of patients discontinuing the pill. This development has underscored the challenges in developing an effective and tolerable weight loss treatment for individuals with obesity.

Comparison with Competitors and Hope for Once-Daily Version

Analysts have drawn comparisons with competitors such as Eli Lilly, noting that Pfizer’s twice-daily danuglipron exhibited higher rates of patient discontinuation compared to Eli Lilly’s once-daily pill due to adverse side effects. There is optimism that a once-daily version of danuglipron may offer improved tolerability and lessen gastrointestinal side effects. However, the overall effects will remain uncertain until the mid-stage trial data is unveiled in the coming year.

Prevalence of Obesity and Implications

The significance of this development is underscored by the prevalence of obesity, affecting more than 2 in 5 adults, with approximately 1 in 11 adults experiencing severe obesity. The halt in the development of the twice-daily weight loss pill has brought attention to the challenges in addressing the complex and pervasive issue of obesity, especially in the context of developing effective and well-tolerated pharmaceutical interventions.