Hypotension following the initiation of tizanidine in a patient treated with an angiotensin converting enzyme inhibitor for chronic hypertension

Centrally acting alpha-2 adrenergic agonists are one of several pharmacolog ic agents used in the treatment of spasticity related to disorders of the c entral nervous system. In addition to their effects on spasticity, certain adverse cardiorespiratory effects have been reported. Adults chronically tr eated with angiotensin converting enzyme inhibitors may have a limited abil ity to respond to hypotension when the sympathetic response is simultaneous ly blocked. The authors present a 10-year-old boy chronically treated with lisinopril, an angiotensin converting enzyme inhibitor, to control hyperten sion who developed hypotension following the addition of tizanidine, an alp ha-2 agonist, for the treatment of spasticity The possible interaction of t izanidine and other antihypertensive agents should be kept in mind when pre scribing therapy to treat either hypertension or spasticity in such patient s.