Severe hyponatremia is often drug‐induced. 10‐year results of a prospective pharmacovigilance program

We conducted a prospective evaluation of drug-induced severe hyponatremia (adverse drug reaction (ADR)) through the Prospective Pharmacovigilance Program from Laboratory Signals at Hospital over a period of 10 years. Cases of serum sodium (Na(s)) < 116 mM were recorded from July 2007 to June 2017 (first period). Also cases of Na(s) 116-122 mM were recorded from July 2012 to June 2017 (second period). Drugs were the primary cause of severe hyponatremia. The incidence rate of Na(s) < 116 mM by drugs was increased threefold over the decade. Compared with other causes of hyponatremia, patients with adverse drug reaction-serum sodium (ADR-Na(s)) in the first period were older (79 years (interquartile range (IQR) 68.6-89 vs. 65 years (IQR 48-81); P < 0.001) and were more often women (70.8% vs. 48.9% men, P < 0.001); in the second period were also older (79 years (IQR 65.3-89) vs. 63 years (IQR 46-80.6); P < 0.001) and were more often women (70% vs. 53%, P = 0.002), and ADR-Na(s) occurred more often in summer. The most frequent therapeutic groups of culprit drugs were the cardiovascular system and nervous system. The 65.3% in the first period and 71.2% in the second period of the ADR-Na(s) cases responded to hydration and had been diagnosed with hypovolemic hyponatremia.