The effect of naloxone on the hypotensive and bradycardiac action of clonidine was studied in 27 hospitalized patients with uncomplicated mild-to-moderate essential hypertension. In a double-blind, crossover study, clonidine, 0.3 mg/day orally for 3 days, significantly reduced systolic and diastolic blood pressure and heart rate, whereas placebo was ineffective. Naloxone, 0.4 mg given intraveno...

BACKGROUND Epidural clonidine produces analgesia without motor impairment, and is associated with a local anesthetic-sparing effect during labor. The authors have recently demonstrated that epidural neostigmine initiates selective labor analgesia devoid of adverse effects. Both drugs possess common analgesic mechanisms mediated through spinal acetylcholine release. This study evaluates their ep...

  Clonidine, an α2-adrenergic receptor agonist not only induces analgesia but also prolongs the effects of local anesthetic substances. In the present study the effects of clonidine on spontaneous and formalin-induced electrical activity from dorsal skin nerve were investigated. The results showed that clonidine (0.5 mM) decreased the formalin effect on electrical nerve activity whereas clonidi...

Clonidine is reported to inhibit the az-adrenoceptor mediated pinnal reflex in mice (3). Clonidine produces its effect by acting as an oc2-adrenergic autoreceptor agonist (1). As such, clonidine is also agonist for presynaptic histamine Hz-receptors (8). To test whether the clonidine-induced inhibition of the pinnal reflex is mediated through adrenergic and/or histaminergic system, the interact...

Recording of multi-unit sympathetic activity were made from muscle branches of the peroneal nerve during i.v. bolus injection of 100 to 275 micrograms clonidine in seven hypertensive patients. Blood pressure was reduced in all patients, but sympathetic activity and heart rate could either increase or decrease. When plasma levels of clonidine were low, sympathetic activity tended to increase, an...

The use of alpha-2 agonists in anesthesia practice is not new and had been started in the late twentieth century. Clonidine, the prototype of alpha-2 agonist, is widely used as an adjunct in anaesthesia and pain medicine. Dexmedetomidine is the next generation alpha-2 agonist with high selectivity for alpha-2 receptors (1600:1). This agent is 10 times more potent than clonidine and associated w...

Recordings of multi-unit sympathetic activity were made from muscle branches of the peroneal nerve during i.v. bolus injection of 100 to 275 pg clonidine in seven hypertensive patients. Blood pressure was reduced in all patients, but sympathetic activity and heart rate could either increase or decrease. When plasma levels of clonidine were low, sympathetic activity tended to Increase, and when ...

BACKGROUND This systematic review and meta-analysis investigates the efficacy and safety of clonidine as a sedative in critically ill patients requiring invasive mechanical ventilation. METHODS We performed a comprehensive search of MEDLINE, EMBASE, CINAHL and the Cochrane trial registry. We identified RCTs that compared clonidine to any non-clonidine regimen in critically ill patients, exclu...

The effect of short-term diuretic treatment on the action of clonidine was evaluated in eight subjects with mild, uncomplicated hypertension. A single oral dose of clonidine (0.3 mg) was given before and after 1 week of therapy with hydrochlorothiazide, 50 mg, and amiloride, 5 mg, taken daily. Changes in mean arterial pressure, heart rate, plasma norepinephrine and epinephrine levels, and plasm...

crossover study, clonidine, 0.3 mg/day orally for 3 days, significantly reduced systolic and diastolic blood pressure and heart rate, whereas placebo was ineffective. Naloxone, 0.4 mg given intravenously on the third day of clonidine treatment, caused a rapid increase in blood pressure and heart rate in 14 patients (reacting group), but was ineffective in the remaining 13 patients (nonreacting ...