Ireland. Since 1997, the Irish Medicines Board has received reports of three patients undergoing long-term thyroid replacement therapy who inadvertently received 50 microgram tablets in place of 100 microgram tablets, in one case leading to the development of fetal hypothyroidism.

While both tablets are white, the 100 microgram tablet is heavier and larger than the 50 microgram tablet and the name and strength is engraved on each tablet. In view of the potentially serious implications of the patient receiving the wrong strength, prescribers and pharmacists are reminded to advise patients to check their tablets, particularly if two strengths are dispensed.

Reference: Irish Medicines Board, Drug Safety Newsletter No. 8, September 1998.