FDA updates GLP-1 receptor agonist labels to add gastroparesis as a recognised adverse effect

FDA has issued required labelling updates to all approved GLP-1 receptor agonist (GLP-1 RA) products — semaglutide (Ozempic, Wegovy, Rybelsus), liraglutide (Victoza, Saxenda), tirzepatide (Mounjaro, Zepbound), dulaglutide (Trulicity), and exenatide (Byetta, Bydureon) — to formally list gastroparesis as a recognised adverse effect under Section 6 (Adverse Reactions) and to update Warnings and Precautions to include guidance on drug interactions mediated by delayed gastric emptying. The Warnings section now specifically states that GLP-1 RAs can alter the absorption of concomitant oral medications and recommends monitoring for efficacy changes in drugs with narrow therapeutic indices (e.g. levothyroxine, oral contraceptives, digoxin). See related news: Ozempic cardiovascular label update and GLP-1 gastroparesis label update.

GLP-1 receptor agonists reduce gastric emptying rate via multiple mechanisms: direct activation of GLP-1 receptors on the gastric enteric nervous system, reduction in vagal tone, and decreased gastric acid secretion. This is part of the intended mechanism that contributes to satiety and post-prandial glucose lowering — slowed gastric emptying reduces the post-meal glucose excursion. However, in a subset of patients, particularly at higher doses or in those with pre-existing autonomic neuropathy, this effect can become clinically significant gastroparesis — defined as delayed gastric emptying confirmed by gastric emptying scintigraphy (solid meal, 4-hour study), with symptoms of nausea, vomiting, bloating, early satiety, and abdominal pain. Related: diabetes medications pharmacology guide and GLP-1 pancreatitis review.

Delayed gastric emptying significantly alters the absorption of co-administered oral medications. Clinical implications: (1) Narrow TI oral drugs — levothyroxine (T4 absorption highly dependent on gastric pH and emptying rate — separate administration by ≥4 hours from GLP-1 RA injection), digoxin (Cmax reduced, tmax prolonged); (2) Oral contraceptives — delayed absorption may theoretically reduce contraceptive efficacy during peak GLP-1 action; (3) Antibiotics with concentration-dependent efficacy — delayed Cmax may affect peak-dependent killing. Conversely, enteric-coated drugs may have enhanced protection with slowed transit. Pharmacists should review concomitant narrow-TI oral medications in all patients on GLP-1 RAs. See drug interactions guide and bioavailability.

If gastroparesis symptoms emerge: (1) Assess severity — clinically significant vomiting, weight loss >10%, or electrolyte disturbance warrants dose reduction or cessation; (2) Dose reduction — reducing GLP-1 RA dose often partially resolves gastroparesis; (3) Diet modification — small, frequent meals; low-fat, low-fibre diet during symptomatic periods; avoid carbonated beverages; (4) Prokinetic consideration — metoclopramide (short-term only, risk of tardive dyskinesia with prolonged use) or domperidone in appropriate jurisdictions; (5) Temporary GLP-1 RA pause — in patients undergoing procedures requiring fasted state (surgery, endoscopy), GLP-1 RAs should be withheld for at least 1 week (weekly formulations) due to risk of pulmonary aspiration from residual gastric contents. See medication safety guide.