CLONIDINE

introduction

Clonidine is a drug that is mainly used in intensive care medicine. In addition to high blood pressure, especially very high, dangerous blood pressure values, clonidine is also used for restlessness. Its use in the treatment of withdrawal syndromes, such as opioid or alcohol withdrawal, is a specialty.

Mode of action

Clonidine affects that autonomic nervous system. The autonomic nervous system consists of two parts. Of the Sympathetic is the invigorating part, which is particularly active during excitement, stress and struggle. Opposed to this is Parasympathetic nervous systemwho in many cases has exactly opposite tasks and e.g. is active during rest, sleep and digestion. The Blood pressure regulation is an essential task of the autonomic nervous system. There is usually a balance between these two proportions. In special situations, however, there may be shifts in equilibrium. This system has a brake to prevent or suppress an overshooting of the sympathetic component. Clonidine amplifies this brake by holding the same receptors (? 2 receptors) activated. As so-called? 2 mimetics (also? 2 agonist) they suppress the release of certain exciting messenger substances (Neurotransmitters or catecholamines such as noradrenaline), which are essential for blood pressure regulation. ? 2- Receptors are thus braking receptors and also involved in the transmission of pain stimuli, which explains the pain-relieving effect of clonidine.

application

Clonidine Today it is hardly relevant for the usual high blood pressure therapy, because the side effects for the patient are considerable. The main point of attack of clonidine lies in the nervous system, which is of great importance for symptom relief in withdrawal therapy, including Alcohol or opioid withdrawal is. At a withdrawal problems arise that are caused by a flood of exciting messenger substances (Catecholamine overflow), which reduces the clonidine by activating the inhibitory receptors, which then leads to the release of the excitatory substances (esp. Norepinephrine) reduced. Clonidine gets into the nervous system easily. In the Intensive care can clonidine for postoperative calming (Sedation) and the Pain therapy (as a coanalgesic) can be used. The use at severe increase in blood pressurewhich is associated with life-threatening blood pressure values (Hypertensive crisis). With blood pressure regulation is also the Baroreceptor reflex important. These pressure-sensitive receptors, which are located at certain points in the arterial vascular system, react more sensitively to changes in blood pressure due to clonidine. It comes to slow heartbeat with reduced blood ejection volume and expansion of vessels (Vasodilation). As a result, the Blood pressure. It is usually given as an infusion through the veins (intravenous, i.v.). Clonidine is also available as an injection under the skin is available (subcutaneously, s.c.).

Side effects

The Side effects of clonidine can be explained by the localization of the α2 receptors. α2 receptors are not only found in the sympathetic part of the autonomic nervous system, but also, for example, on Blood vessels. This can lead to circulatory problems, especially when changing the body position from lying to standing (orthostatic dysfunction) with a drop in blood pressure. This can not only be the result of the activation of the receptors on the vessels, but also the result of the reduced activity of the sympathetic nervous system, which then leads to a relative predominance of the sympathetic opponent, because the parasympathetic component is not influenced. This aspect also leads to undesirable effects such as Dry mouth. More side effects can occur fatigue and decreased performance be. Sudden discontinuation of clonidine can lead to an excessive reaction with the opposite effect (Rebound phenomenon).