Cabergoline contained in Dostinex is an agonist of dopamine receptors and – as such – is able to mimic its biological effects. In particular, cabergoline acts on D2 receptors (type 2 dopaminergic receptors) located on cells responsible for prolactin release that are found in the anterior pituitary. By inhibiting the release of prolactin, cabergoline is able to interrupt the performance of the biological functions connected to it.
Dostinex is indicated in the treatment of:
- Prolactin-secreting pituitary adenomas (a hormone used to stimulate the mammary glands and to produce milk);
- Hyperprolactinemia, that is, elevated blood concentrations of prolactin;
- Parkinson’s disease;
- Galactorrhea, ie the abnormal secretion of milk in women who are not breastfeeding;
- In adjunctive acromegaly therapy.
Dostinex also interacts with dopaminergic neurons in the nigrostriatal area of the brain. In patients with Parkinson’s disease, there is a degeneration of nigrostriatal dopaminergic neurons and a deficit of the enzymes responsible for the synthesis of dopamine. This is why – for the treatment of this pathology – drugs are used that can act directly on dopaminergic receptors, such as cabergoline.
The pituitary gland is a gland the size of a bean placed in the turcic saddle, under the brain, and is responsible for all the hormonal production of the organism. In some cases this gland may develop abnormalities or small benign hormone-secreting tumors. A prolactinoma, for example, that is a tiny benign tumor that produces prolactin, a typically female hormone used to produce breast milk, can create impotence and is easily treatable with drugs like cabergoline. Another common cause of erectile dysfunction, very common among the over 50s, is instead circulatory: if the heart loses its firmness and no longer pumps blood adequately, as in hypertensives, cardiopaths and those suffering from vitiated circulation, it may happen that the cardiac output is not powerful enough to reach the penis in the vicinity of a relationship and, consequently, you will not get an erection or it will not last long enough.
In motor complications in Parkinson disease, Dostinex administered orally in combination with L-Dopa can be used to supplement the therapeutic efficacy of L-Dopa, reduce the severity and duration of motor blocking episodes, and at the same time reduce doses of L-Dopa. The drug thus makes it possible to attenuate the motor fluctuations and to reduce the dyskinesias by the decrease in dosage of L-Dopa.
In the early stage of Parkinson’s disease, Dostinex can control motor symptoms well but especially halve the risk of motor complications. This clinical effect was recently confirmed by a functional imaging study, Positron Emission Tomography (PET) scoring the dopaminergic endings of the nigrostriated pathway with a radiotracer (18 Fluoro dopa) that showed a slower progression of disease in Parkinson’s patients treated with ropinirole compared to patients treated with L-Dopa. This is for the first time the demonstration of a possible neuroprotective effect of a dopaminergic agonist in Parkinson’s disease.
How long do the effects of Dostinex last?
Dostinex is a dopaminergic with high affinity for the ergot-derived D2 receptor, but appears to be better tolerated than bromocriptine. Its pharmacokinetic profile is such that a treatment requires only two weekly doses. After an initial dose of 0.25 mg twice weekly, the maintenance dose of 0.25-1 mg twice weekly will be achieved by a progressive increase of 0.5 mg / week every 4 weeks. Cabergoline can also be successfully administered to patients who are intolerant or resistant to bromocriptine.
Normalization of prolactinemia with restoration of fertility is achieved in more than 90% of cases. Patients should be informed in advance, emphasizing the possibility of pregnancy even before the first return of the rules to allow the introduction of contraception if necessary. In 60% of cases, drug treatment also stabilizes or even decreases the size of the tumor. It is for this reason that this approach is also the first choice of treatment for macroprolactinoma, especially if it is invasive because of the low success rate of surgery in this situation. The only exception to this rule should be the neurosurgical emergency.
After more than two years of treatment, if the prolactin level is normalized and the MRI shows no more adenoma image, a stop of cabergoline can be tried with chances of remission. A low risk of cardiac valvulopathy may exist in the treatment of prolactinomas with cabergoline, but current data are not sufficient to discontinue this treatment for this indication. However, echocardiography may be recommended for long-term high-dose therapy.
When do I need to see a Doctor?
Keeping regular medical appointments is essential during the entire course of Dostinex therapy. Blood panels should be run in order to establish the efficacy of the current dose and adjust the posological schedule, if needed. For instance, in case of prolactinoma – the most common pituitary adenomas – the efficacy of Dostinex is well demonstrated, both to normalize prolactinemia and to reduce tumor volume, if the drug is taken at a right dose. The individual response of patient should be determined using laboratory tests with maximal intervals of 4 weeks.
Seek medical help if you experience
If any of the side effects listed in patient instructions gets serious, or if you notice any side effects not listed in the leaflet supplied with the drug, please tell your doctor or pharmacist.
Possible allergic reactions
There are four types of allergic reactions towards Dostinex. But the two most common forms of allergic reactions are so-called immediate or delayed hypersensitivity. The immediate allergic reaction to Dostinex happens when the antibodies put in contact with an allergen identify it as such and attack it. They send messages to certain white blood cells (mast cells and basophils) that release inflammatory substances responsible for the symptoms of allergy. These are manifested in the minutes or hours that follow. In the case of a delayed allergic reaction, symptoms do not appear for several hours or even days after exposure. There, it is particular white blood cells that trigger the allergy. The allergen is captured by” antigen presenting “cells, which then migrate into the ganglia and present it to T cells. These cells, through other mediators and signals, cause the inflammatory reaction.