--- title: Pfizer Shares Drop As Obesity Drug Halted Over Safety Fears description: The drugmaker will stop work on lotiglipron based on data from phase 1 clinical trials and lab measurements showing elevated enzyme levels. canonical: https://time.com/6290227/pfizer-shares-drop-after-lotiglipron-pause/ author: TIME article:opinion: false article:content_tier: free article:published_time: 2023-06-26T15:54:17.000Z article:modified_time: 2026-02-24T16:04:44.198Z article:section: Health og:title: Pfizer Shares Drop After It Halts Development of Obesity Drug Due to Safety Concerns og:description: The drugmaker will stop work on lotiglipron based on data from phase 1 clinical trials and lab measurements showing elevated enzyme levels. og:url: https://time.com/6290227/pfizer-shares-drop-after-lotiglipron-pause/ og:site_name: TIME og:image: https://static.time.com/v3/assets/bltea6093859af6183b/bltd91d59183d916c37/698a3e28929fada581bf9efd/pfizer-weight-loss-drug-development-pause.jpg?branch=production&width=2400&quality=75&auto=webp&crop=16:9 og:image:width: 1200 og:image:height: 675 og:image:alt: Pfizer Acquires Wyeth For $68 Billion og:type: article twitter:card: summary_large_image twitter:title: Pfizer Shares Drop After It Halts Development of Obesity Drug Due to Safety Concerns twitter:description: The drugmaker will stop work on lotiglipron based on data from phase 1 clinical trials and lab measurements showing elevated enzyme levels. twitter:image: https://static.time.com/v3/assets/bltea6093859af6183b/bltd91d59183d916c37/698a3e28929fada581bf9efd/pfizer-weight-loss-drug-development-pause.jpg?branch=production&width=2400&quality=75&auto=webp&crop=16:9 ---  # Pfizer Shares Drop After It Halts Development of Obesity Drug Due to Safety Concerns ## Video: Don’t Use Artificial Sweeteners for Weight Loss, WHO Says [Watch (HLS stream): Don’t Use Artificial Sweeteners for Weight Loss, WHO Says](https://cdn.jwplayer.com/manifests/tQEq3EOC.m3u8) (0:59)  _Published 2023-05-16. Artificial sweeteners may not help people lose weight, the World Health Organization said in new guidelines that warned against products like diet sodas._ by [Matthew Griffin / Bloomberg](https://time.com/author/bloomberg/) ## Matthew Griffin / Bloomberg Jun 26, 2023 3:54 PM UTC  Pfizer said it will stop work on weight loss drug lotiglipron due to safety concerns raised during phase 1 clinical trials. Pfizer said it will stop work on weight loss drug lotiglipron due to safety concerns raised during phase 1 clinical trials.Mario Tama—Getty Images by [Matthew Griffin / Bloomberg](https://time.com/author/bloomberg/) ## Matthew Griffin / Bloomberg Jun 26, 2023 3:54 PM UTC [Pfizer Inc.](https://time.com/collection/time100-companies-2022/6159476/pfizer/) shares fell after it halted early development of an oral drug for[ weight loss](https://time.com/6289928/new-weight-loss-drugs-orforglipron-retatrutide-tirzepatide/) on safety concerns, raising investor anxiety about an alternative therapy the company is still developing. The drugmaker will stop work on lotiglipron based on data from phase 1 clinical trials and lab measurements showing elevated levels of enzymes called transaminases from an ongoing mid-stage study, according to a statement Monday. The enzymes play a key role in liver function. None of the patients reported liver side effects or symptoms, Pfizer said. The shares fell as much as 5.6% at 10:51 a.m. in New York, their biggest intraday drop since February, 2022. Struggling to recover from waning [Covid vaccine](https://time.com/6287732/new-covid-19-vaccine-strains/) demand, Pfizer is racing to catch up with [Novo Nordisk A/S](https://time.com/6281987/weight-loss-pill-semaglutide/) and Eli Lilly & Co. in an obesity-treatment market estimated to grow to more than $100 billion in size in the coming years. Pfizer is pinning its hopes on danuglipron, another treatment still in development, to compete with the likes of Novo’s Wegovy and Lilly’s Mounjaro, both seen as blockbuster market leaders. --- ### More from TIME --- Lilly and Novo are also developing oral obesity drugs that would save patients the trouble of self-injecting them. Analysts raised concern that the need for patients to take danuglipron twice a day could hurt its competitiveness. “A twice-daily pill could prove challenging, assuming all else is equal, leaving Pfizer’s $10 billion peak-sales estimate for danuglipron looking optimistic,” Bloomberg Intelligence analysts John Murphy and Mila Bankovskaia said in a note. Lotiglipron is a once-daily oral treatment, and Pfizer’s decision follows positive data from a competing experimental treatment from Lilly, orforglipron, according to the Bloomberg analysts. The twice-daily version of danuglipron is in mid-stage studies, and Pfizer said it hasn’t seen the same elevated enzymes in more than 1,400 patients enrolled in tests. The company was developing two treatments with the intent of choosing one to move forward with, said [William Sessa](https://www.pfizer.com/people/medical%5Fexperts/heart%5Fmetabolic%5Fdiseases/william%5Fsessa-phd), senior vice president and chief scientific officer for internal medicine research, in the company’s statement. Pfizer expects to finalize plans for danuglipron’s late-stage development by the end of 2023 and is working on a once-daily, modified release version. Pfizer’s once-a-day version of danuglipron will likely take time to develop, while Lilly has moved its daily drug to late-stage trials, JPMorgan analysts led by Chris Schott wrote in a note. ```json [{"@context":"https://schema.org","@type":"NewsArticle","@id":"https://time.com/6290227/pfizer-shares-drop-after-lotiglipron-pause/","mainEntityOfPage":{"@type":"WebPage","@id":"https://time.com/6290227/pfizer-shares-drop-after-lotiglipron-pause/"},"headline":"Pfizer Shares Drop After It Halts Development of Obesity Drug Due to Safety Concerns","datePublished":"2023-06-26T15:54:17.000Z","dateModified":"2026-02-24T16:04:44.198Z","description":"The drugmaker will stop work on lotiglipron based on data from phase 1 clinical trials and lab measurements showing elevated enzyme levels.","url":"https://time.com/6290227/pfizer-shares-drop-after-lotiglipron-pause/","keywords":["Drugs","wire","healthscienceclimate"],"thumbnailUrl":"https://static.time.com/v3/assets/bltea6093859af6183b/bltd91d59183d916c37/698a3e28929fada581bf9efd/pfizer-weight-loss-drug-development-pause.jpg?branch=production&width=1200&quality=75&auto=webp&crop=1200:675&height=675","author":[{"@type":"Person","name":"Matthew Griffin / Bloomberg"}],"articleSection":"Health","image":[{"@type":"ImageObject","url":"https://static.time.com/v3/assets/bltea6093859af6183b/bltd91d59183d916c37/698a3e28929fada581bf9efd/pfizer-weight-loss-drug-development-pause.jpg?branch=production&width=1200&quality=75&auto=webp&crop=1200:675&height=675","width":1200,"height":675,"headline":"Pfizer Acquires Wyeth For $68 Billion","caption":"Pfizer said it will stop work on weight loss drug lotiglipron due to safety concerns raised during phase 1 clinical trials.","creditText":"Mario Tama—Getty Images","representativeOfPage":true}],"publisher":{"@type":"Organization","name":"Time","url":"https://time.com/","logo":{"@type":"ImageObject","url":"https://time.com/images/logo.png","width":528,"height":156},"foundingDate":"March 3, 1923","sameAs":["https://www.facebook.com/time","https://www.instagram.com/time/?hl=en","https://twitter.com/time","https://www.pinterest.com/timemagazine"]}},{"@context":"https://schema.org","@type":"BreadcrumbList","itemListElement":[{"@type":"ListItem","position":1,"item":{"@id":"/section/health/","name":"Health"}},{"@type":"ListItem","position":2,"item":{"@id":"/tag/drugs/","name":"Drugs"}},{"@type":"ListItem","position":3,"item":{"@id":"https://time.com/6290227/pfizer-shares-drop-after-lotiglipron-pause/","name":"Pfizer Shares Drop After It Halts Development of Obesity Drug Due to Safety Concerns"}}]},{"@context":"https://schema.org","@type":"VideoObject","name":"Don’t Use Artificial Sweeteners for Weight Loss, WHO Says","description":"Artificial sweeteners may not help people lose weight, the World Health Organization said in new guidelines that warned against products like diet sodas.","thumbnailUrl":"https://cdn.jwplayer.com/v2/media/tQEq3EOC/poster.jpg?width=720","uploadDate":"2023-05-16T21:02:38.000Z","contentUrl":"https://cdn.jwplayer.com/manifests/tQEq3EOC.m3u8","embedUrl":"https://time.com/6290227/pfizer-shares-drop-after-lotiglipron-pause/","duration":"PT59S","potentialAction":{"@type":"SeekToAction","target":"https://time.com/6290227/pfizer-shares-drop-after-lotiglipron-pause/?jw_start={seek_to_second_number}","startOffset-input":"required name=seek_to_second_number"}}] ```