In hypertension, the usual initial dose of clonidine hydrochloride DIXARIT is 50 to 100 micrograms three times daily by mouth, increased every second or third day according to response; the usual maintenance dose is 300 to 1200 micrograms daily but doses of 1800 micrograms or more daily may sometimes be required. Modified-release preparations have been used. Clonidine may also be given by transdermal delivery systems that are applied once a week and deliver 100 to 300 micrograms of clonidine base daily at a constant rate.
Clonidine hydrochloride may be given by slow intravenous injection over 10 to 15 minutes in hypertensive crises, usually in doses of 150 to 300 micrograms. The effect usually appears within 10 minutes, but transient hypertension may precede hypotension if the injection is given too rapidly. The hypotensive effect reaches a maximum about 30 to 60 minutes after administration and the duration is about 3 to 7 hours; up to 750 micrograms may be given intravenously over 24 hours. Although oral administration does not produce a sufficiently rapid hypotensive effect for use in an emergency situation, a dose of 100 to 200 micrograms initially followed by 50 to 100 micrograms every hour until control of blood pressure is achieved or a maximum of 500 to 800 micrograms is reached, has been recommended for the control of severe hypertension.
In the prophylaxis of migraine or recurrent vascular headaches and in the treatment of menopausal flushing, a dose of 50 micrograms DIXARIT twice daily by mouth has been used, increased, if there is no remission after 2 weeks, to 75 micrograms twice daily.
In the management of severe cancer pain, clonidine hydrochloride may be given by continuous epidural infusion with an opioid, in an initial dose of 30 micrograms/hour, adjusted according to response.