Generality
Dopaminergic agonists are molecules capable of mimicking the action of dopamine (an endogenous neurotransmitter), binding to its receptors and activating them.
Some of these molecules are used in the medical field as drugs for the treatment of different types of diseases and disorders, such as - for example - Parkinson's disease, restless legs syndrome, and some types of prolactin-secreting pituitary tumors.
Furthermore, certain dopaminergic agonists are also used in the psychiatric field.
Action mechanism
As mentioned, dopamine agonists perform their action by binding and activating the receptors of this particular neurotransmitter.
When dopamine binds to its own receptors, it induces a change in the conformation of the latter. Receptor modification - in turn - gives rise to a cascade of chemical signals that culminates with a biological response.
Dopaminergic agonists possess a chemical structure that allows them to bind to dopamine receptors, thus inducing structural modifications similar to those induced by the endogenous neurotransmitter, thus mimicking its action.
Classification
Dopaminergic agonists can be divided according to their ability to induce conformational changes in dopamine receptors.
Total dopaminergic agonists
Total dopaminergic agonists are able to bind to dopamine receptors and to cause a conformational modification that allows to obtain a maximum effect, therefore, a total response.
Among the total dopaminergic agonists used in the medical field, we recall:
- Bromocriptine is a drug used in the treatment of various diseases, including prolactin-secreting pituitary adenomas, hyperprolactinemia, galactorrhoea, prolactin-dependent amenorrhea, acromegaly, prolact-dependent male hypogonadism, neuroleptic malignant syndrome and Parkinson's disease.
- Cabergoline, also used in the treatment of prolactin-secreting pituitary adenomas, hyperprolactinemia, galactorrhoea and Parkinson's disease.
- Lisuride, pergolide, pramipexole, ropinirole, rotigotine, active ingredients used both in the treatment of Parkinson's disease and in the treatment of restless legs syndrome.
- Apomorphine, another drug used to treat Parkinson's disease.
Partial dopaminergic agonists
Partial dopaminergic agonists are able to bind to dopaminergic receptors, but they induce a conformational modification that does not allow obtaining a total pharmacological response. Therefore, receptor activation is only partial and - consequently - maximum effect is not achieved.
Among the partial dopaminergic agonists used in the medical field, we mention aripiprazole . It is an atypical antipsychotic drug, used to treat schizophrenia and manic episodes in patients with bipolar disorder.
Side effects
Like any other drug, dopaminergic agonists can also cause side effects.
The type of adverse effects may vary depending on the type of active ingredient chosen and according to the pathology to be treated.
However, some side effects are common to the entire drug category. Among these, we recall:
- agitation;
- Hallucinations;
- Nausea and vomit;
- Anorexia;
- Increase or loss of body weight;
- Insomnia;
- Fatigue or weakness;
- Drowsiness;
- Orthostatic hypotension;
- Tachycardia;
- Dizziness.
