Are omeprazole or H2-blockers contraindicated in a patient with thrombocytopenia and splenectomy?/n

Fråga: Are omeprazole or H2-blockers contraindicated in a patient with thrombocytopenia and splenectomy? A 30-year-old woman who had thrombocytopenia as a child, treated with splenectomy and was cured, but now trombocytopenia has reoccurred and she also has a gastric ulcer which needs to be treated.

Sammanfattning: Cimetidine, ranitidine, famotidine and omeprazole can all cause thrombocytopenia as an adverse effect, but the incidence is low. It is not contraindicated to give these drugs in thrombocytopenic diseases but it should be given with a clear indication.

Svar: This question has previously been answered in Drugline (1, 2). Cimetidine (Tagamet), ranitidine (Zantac), famotidine (Pepcid), and omeprazole (Losec), a proton pump inhibitor, are all used in treatment of gastric ulcers. Cimetidine, ranitidine and omeprazole may cause thrombocytopenia as an adverse effect, according to FASS (3). Cimetidine and ranitidine may cause thrombocytopenia by a kind of autoimmune effect or by a kind of inhibition of the growth of granulocyte colonies (1). A search in SWEDIS gave a total of 24 cases of thrombocytopenia possibly due to cimetidine, ranitidine, famotidine or omeprazole (3). A search in Medline revealed several case reports of thrombocytopenia with omeprazole, cimetidine, ranitidine, or famotidine treatment. It is not possible out of our data to determine which agent is the least possible to cause thrombocytopenia. The thrombocytopenic incidents with these medications are very few.