Sympathomimetics: Effects, Uses & Risks

Sympathomimetics are agents that result in stimulation of the sympathetic nervous system. The sympathetic nervous system belongs to the autonomic nervous system and is involved in various bodily functions. Basically, the excitation of this nerve puts the body into a performance-enhancing state. Physiologically, this is the case, for example, during stress. Sympathomimetics are used, among other things, to treat the common cold, asthma and low blood pressure. Some sympathomimetics require a prescription, while other sympathomimetics are available without a prescription. Caution is advised when taking them. Undesirable side effects cannot be ruled out even with nonprescription sympathomimetics, such as those found in nasal sprays.

What are sympathomimetics?

Sympathomimetics are active substances that additionally activate the sympathetic nervous system. The sympathetic nervous system belongs to the autonomic nervous system. This part of the organism is also called the autonomic nervous system because it is largely not subject to voluntary control. The sympathetic nervous system influences functions that put the human body in a heightened state of performance. In pharmacology, two different classes of sympathomimetics are distinguished. There are so-called alpha- and beta-sympathomimetics. Most drugs based on sympathomimetics require a prescription because they significantly interfere with different bodily functions and can also bring risky effects.

Pharmacologic effects on the body and organs

The sympathetic nervous system, which belongs to the autonomic nervous system, has the task of putting the body into increased readiness to perform under stress and in emergency situations. When the sympathetic nervous system is stimulated by taking sympathomimetics, alertness, blood pressure, and blood glucose levels increase. Furthermore, there is an expansion of the respiratory tract and an associated short-term increase in performance. A euphoric state sets in and appetite is greatly reduced. With regard to the mechanism of action, a distinction is made between direct and indirect sympathomimetics. The former exert their effect by mimicking the neurotransmitters norepinephrine and epinephrine, thus activating the adrenoreceptors. Indirect sympathomimetics lead to an increase of the messenger substances in the synaptic cleft of the human brain. The level is kept high partly by inhibited reuptake and partly by increased release. Substances of this type include ephedrine and amphetamine. Furthermore, these agents are divided into alpha- and beta-sympathomimetics. Alpha-sympathomimetics bind predominantly to alpha-adrenoreceptors. These agents constrict blood vessels and stabilize blood pressure. Beta-sympathomimetics have a respiratory dilating effect. In addition to these two classes of substances, there are derivatives that influence both alpha and beta adrenoreceptors. These alpha- and beta-sympathomimetics include, for example, the active ingredients metaraminol and norephedrine.

Medical use and use for treatment and prevention.

Taking alpha sympathomimetics causes smooth muscle cells to contract, resulting in what is known as vasoconstriction (vasoconstriction of blood vessels). This effect is used in medical applications, for example, to treat inflammation of the mucous membranes of the nose. The sympathomimetics cause the mucous membrane to decongest and thus relieve the patient’s symptoms. Alpa- sympathomimetics are therefore often contained in nasal sprays. However, oral medication of sympathomimetics is also possible. These substances have a blood pressure-stabilizing effect and are thus used to treat fluctuations in blood pressure. Beta- sympathomimetics are mainly used in pulmonary medicine. In medicine, substances that act on the so-called beta-2 receptors are mainly used. One of these substances is fenoterol. To ensure that these substances exert their effect only locally and not systemically, they are often inhaled in the form of gases. In asthma patients, these drugs can provide relief by dilating the bronchial tubes and thus facilitating the breathing process. Beta- sympathomimetics are also prescribed for the treatment of chronic obstructive pulmonary disease, or COPD. Other recognized indications for sympathomimetics are ADHD, allergies, conjunctivitis, fatigue, obesity, bronchitis and narcolepsy. The latter describes a disorder of the sleep-wake rhythm.Sufferers regularly fall into microsleep.

Risks and side effects

The spectrum of action of sympathomimetics is broad. The risks and side effects depend on the type of sympathomimetic and its dosage. Many drugs that have a stimulant effect on the sympathetic nervous system are available by prescription. Some of these substances such as MDMA, amphetamines or cocaine are common party drugs and are sold illegally to sometimes underage users. The use of these drugs without a necessary indication is not recommended. Side effects such as itching, redness, irritation of the nasal mucous membranes, nausea, diarrhea and gastrointestinal complaints may occur. As the dosage of these substances as a party drug is self-directed, possible serious side effects cannot be ruled out. Especially in combination with alcohol, a fatal cardiac arrest can occur. Alpha sympathomimetics can generally lead to increased irritability. Concentration and sleep disturbances can be distressing side effects for the patient. Nose drops containing alpha sympathomimetics should only be taken for a short period of time. In the long term, they damage the nasal mucosa and can lead to dependence. Beta- sympathomimetics can cause cardiac arrhythmias in addition to a general feeling of weakness and increased sweat production.