Zealand Pharma's obesity drug survodutide is back in the spotlight — and not for the right reasons. New data from a late-stage clinical trial showed that nearly one in five patients (18%) dropped out due to gastrointestinal side effects, spooking investors and sending the Danish drugmaker's shares tumbling as much as 13%.

The pattern is becoming familiar. Back in June, data from other late-stage studies on survodutide — developed in partnership with Boehringer Ingelheim — showed a 25% dropout rate, triggering a sharp single-day stock decline. Analysts point to the trial's limited dosing flexibility as a key culprit: patients tended to quit while doses were being ramped up, and doctors had little room to adjust when side effects emerged.

On the efficacy side, survodutide did show meaningful results — reducing average blood sugar by up to 1.21 percentage points from a baseline of 7.4%, while also improving waist circumference and insulin sensitivity.

By the Numbers:

• 18% of patients quit the latest trial due to side effects
• 25% dropout rate seen in June's earlier late-stage studies
• 1.21 percentage points reduction in average blood sugar from a 7.4% baseline
• 13% drop in Zealand Pharma's share price following the new data

Why it matters: Tolerability is increasingly a make-or-break factor in the competitive obesity drug market. High dropout rates raise real questions about survodutide's viability compared to rivals, and could influence prescribing decisions and regulatory outcomes down the line.