Dopamine, along with epinephrine and norepinephrine, belongs to the catecholamines. Dopamine is both a hormone and an important neurotransmitter, produced in natural form by the human body and used in artificial form as a drug. Dopamine as a drug is most often used to stabilize the cardiovascular system after shock and in the treatment of Parkinson’s disease, then as L-DOPA.
What is dopamine?
In people suffering from Parkinson’s disease, it has been found that the concentration of dopamine in the brainstem is about 90% lower than in healthy people. Dopamine is one of the most important hormones in the human body. It also functions as a neurotransmitter, i.e. – to put it simply – it is responsible for the transmission of sensations and feelings. It is thanks to this property that dopamine has been popularly given the attribute happiness hormone. Dopamine is also responsible for the control and blood flow to the internal organs, as well as for the transmission of impulses to the muscles. Chemically, dopamine is a precursor of adrenaline or noradrenaline and belongs to the group of catecholamines.
Pharmacologic action
So far, not all pharmacological effects on body and mind could be researched and described. However, it is undisputed that dopamine is responsible for transmitting impulses to the muscles. If dopamine is missing, the muscles begin to tremble uncontrollably; the patient suffers from Parkinson’s disease. In people suffering from Parkinson’s, it has been found that the concentration of dopamine in the brainstem is about 90% lower than in healthy people. Dopamine is also responsible for the transmission of sensations and perceptions. It seems that dopamine can increase perceptions and sensations. People suffering from psychosis have a demonstrably increased concentration of dopamine compared to healthy people. They therefore perceive their environment more strongly and are unable to distinguish between important and unimportant things or to process sensory impressions correctly. The excess of information eventually leads to psychosis. Dopamine is also thought to play an important role in the development of addictive disorders. The consumption of certain drugs – mainly amphetamines and opiates – leads to an increased release of dopamine – the drug user perceives his environment more clearly or experiences increased feelings of happiness. Dopamine also regulates the blood flow to various internal organs, especially the kidneys. A lack of dopamine can lead to listlessness and depressive moods.
Medical use and application
The stimulatory effects of dopamine on internal organs in particular can be used medicinally. For example, dopamine-containing drugs are used to treat shock in cases of impending failure of the cardiovascular system. Dopamine can also be given prophylactically to support kidney function in cases of impending kidney failure. Dopamine cannot enter the central nervous system due to a natural blood–brain barrier. Therefore, administration of dopamine is not indicated in patients with Parkinson’s disease or even for the treatment of restless legs syndrome. However, in these cases, a prodrug of dopamine, levodopa (L-DOPA), can be given. Dopamine is available as water-soluble dopamine hydrochloride under its generic name. It is administered intravenously and requires a prescription. Preventive use to prevent disease has not yet been found.
Risks and side effects
The administration of dopamine can lead to cardiac arrhythmias, which is why the main application of dopamine – the treatment of shock states – is increasingly taking a back seat. L-DOPA is the best agent to date for the alleviation of Parkinson’s disease. The side effects of L-DOPA are nausea, increased dizziness, loss of appetite, indigestion and low blood pressure. Some patients experience increased sex drive and increased urges to buy things. Therefore, in addition to L-DOPA, other medications are usually given to mitigate the undesirable side effects. In connection with the intake of L-DOPA, a driving ban is discussed again and again. To date, however, a general inability to drive has not been established. Occasionally, patients complain of increased daytime sleepiness. The effect of L-DOPA decreases with the duration of use.However, since Parkinson’s patients must take L-DOPA for the rest of their lives, it is essential, especially in younger patients, to start with a small dose and to increase the amount steadily. After taking it for too long, L-DOPA is almost ineffective.
