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CPC-132 Syndrome of Inappropriate Antidiuretic Hormone Secretion as Adverse Drug Reaction in Hospitalised Patients Treated with Tolvaptan
  1. P Suarez Artime,
  2. C Crespo-Diz,
  3. E Espino-Paisan,
  4. H Esteban-Cartelle,
  5. J Gonzalez Lopez,
  6. T Rodríguez-Jato
  1. Complejo Hospitalario Universitario de Santiago de Compostela, Pharmacy, Santiago de Compostela, Spain


Background Some drugs can cause Syndrome of Inappropriate Antidiuretic Hormone Secretion (SIADH). Tolvaptan is a new drug to treat SIADH. There is a lack of studies about the prevalence of SIADH as an Adverse Drug Reaction (ADR).

Purpose To classify by the Naranjo Algorithm (NA) and to determinate the prevalence of SIADH in hospitalised patients caused by ADR and treated with tolvaptan.

Materials and Methods Two-year descriptive, retrospective, longitudinal, historical cohort study of 33 patients (15 men, 18 women). We sought patients and their clinical characteristics (age, sex, pre-treatment in the week prior to tolvaptan with drugs that could cause SIADH as ADR) using pharmacotherapy management software SINFHOS, Silicon, IANUS and BOT Plus. To determine the probability of ADR, we used the NA. Probability levels based on total score are: definite (>9), probable (5–8), possible (1–4), doubtful (0).

Results 12 of the 33 (6 men, 6 women) patients were treated in the week prior to tolvaptan with drugs that could cause SIADH as ADR. 16 treatments with 10 drugs that could cause SIADH as ADR (1.3 drugs per patient) were found in the week prior to tolvaptan. The 16 treatments detected were classified as possible (12 times), probable (once) and doubtful (three times); average score was 2.6. SIADH could have been caused by a drug in 10 patients and was classified as possible (4 men, 5 women, 7 older than 65, 2 younger), and probable (1 man over 65). Prevalence was 30%, 40% in men and 34% in women, 28% in people older than 65 and 40% in younger people.

Conclusions Our results suggest that some drugs may contribute to the development of SIADH, and there seems to be a greater risk in male patients under 65. Further research is required to evaluate the prevalence and the relative risk of suffering from SIADH as ADR.

No conflict of interest.

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