Wyeth Pharmaceuticals / Zealand Pharma A/S

Atrial Fibrillation

Disease Overview

Atrial fibrillation is the most common sustained cardiac arrhythmia, marked by disorganized atrial electrical activity that produces irregular ventricular response and stagnant atrial blood flow. It dramatically elevates stroke and heart-failure risk, and pharmacologic rhythm control has historically been limited by proarrhythmia and end-organ toxicity of class I/III agents.

Competitive Landscape

In 2005 the rhythm-control AF market was dominated by amiodarone (Cordarone/Pacerone) despite well-known thyroid, hepatic, pulmonary and ocular toxicity, alongside sotalol (Betapace), flecainide (Tambocor), propafenone (Rythmol) and dofetilide (Tikosyn). Sanofi-Aventis was advancing dronedarone (Multaq) as a less-toxic amiodarone follow-on (FDA approved 2009), defining the late-stage competitive bar. Zealand Pharma's antiarrhythmic peptide platform — rotigaptide (ZP123) and the orally active follow-on GAP-134 / danegaptide — pursued a fundamentally different mechanism, modulating cardiac connexin-43 gap junctions to restore conduction without classical ion-channel blockade. The 2005 expansion of the Wyeth–Zealand 2003 collaboration extended discovery into broader gap-junction biology beyond cardiology. Wyeth advanced rotigaptide into Phase 2 in coronary artery disease and AF before the program was discontinued; the molecule never reached market, and Wyeth was absorbed by Pfizer in 2009. Zealand pivoted to peptide therapeutics in metabolic disease, ultimately commercializing glucagon (Zegalogue) and partnering petrelintide with Roche in 2025 — a far more valuable second act than the gap-junction bet predicted.