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April 1991

Histamine2-Receptor Antagonists and Cardiovascular Drugs-Reply

Author Affiliations

Tucson, Ariz

Arch Intern Med. 1991;151(4):815. doi:10.1001/archinte.1991.00400040142037

In Reply. —  We would like to thank Drs Karlstadt and Palmer for bringing to our attention some possible errors in the review of histamine2 antagonists.1 The first involves the extent to which cimetidine causes confusion, particularly in relationship to the other histamine2 antagonists. Our statement was that cimetidine is thought to cause more confusion than ranitidine. While there are no direct comparative studies to confirm this opinion, which is why we did not present it as fact, there is evidence that supports the position. The article2 cited by Karlstadt and Palmer found that the most frequent adverse events associated with cimetidine in hospitalized patients were neuropsychiatric (1.6%), consisting of disorientation, hallucinations, or psychosis. In addition, a review3 of central nervous system complications associated with cimetidine use in hospitalized or "seriously ill" patients found the incidence to be 0.64%, and a second study4 found the

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