Cabergoline is the name given to a drug derived from ergot alkaloids. The drug is used to treat Parkinson’s disease, among other conditions.
What is cabergoline?
Cabergoline is the name given to a drug derived from ergot alkaloids. The drug is used to treat Parkinson’s disease, among other conditions. Cabergoline is an ergoline derivative. The active ingredient is derived from ergot alkaloids and belongs to the group of dopamine receptor agonists. In the treatment of Parkinson’s disease, cabergoline can be administered as a second-line drug. However, its administration usually occurs only when other dopamine receptor agonists, other than ergot alkaloids, are ineffective. In such cases, the prescription of cabergoline usually takes place individually. It is also possible to combine the drug with levodopa. In this way, the symptoms that occur in Parkinson’s disease can be alleviated. Cabergoline is also used for galactorrhea (abnormal milk flow), an excess of the hormone prolactin, and difficulties with weaning. In addition to human medicine, veterinary medicine is also an important area of application for cabergoline. Here, the drug is used for the treatment of malignant tumors on the mammary gland, false pregnancy and purulent inflammation of the uterus (pyometra).
Pharmacological action
One of the typical features of PD is a deficiency of the neurotransmitter dopamine. In this case, the nerve cells in the substantia nigra, which are responsible for releasing the neurotransmitter, are destroyed for reasons that are as yet unknown. However, humans need dopamine to be able to carry out their movements. The absence of dopamine is manifested by symptoms such as muscle tremor, muscle rigidity and restricted movement. Over time, the symptoms progress. To counteract the symptoms caused by Parkinson’s disease, patients are given dopamine. This is usually the precursor molecule levodopa (L-dopa). In the body, however, levodopa is not only converted to dopamine, but also to metabolites that are ineffective, which is caused by various enzymes. Therefore, inhibition of the responsible enzymes is required to keep dopamine levels stable in the blood. It is also necessary to stimulate dopamine receptors (D2) by agonists. Cabergoline is one of these agonists. Apart from its function in motor movements, dopamine also exerts an inhibitory effect within the pituitary gland on the secretion of the hyperphysis anterior lobe hormone prolactin. By agonizing D2 receptors, cabergoline may enhance this effect. The half-life of cabergoline is very long, around 70 hours. With the help of cabergoline, it is possible to regulate the side effects of levodopa, such as disturbances in movement or fluctuations, more effectively, which has been confirmed by several studies. Because cabergoline can stimulate the hormone prolactin, it has an inhibitory effect on milk production in the female mammary gland. This is why it is suitable for treating excessively high prolactin levels. These can be responsible for the absence of periods and ovulation. Following the birth process, cabergoline stops the flow of milk, for which prolactin is responsible, if it is not desired for medical reasons.
Medical use and application
The primary indications for the use of cabergoline include Parkinson’s disease, which is a chronic neurological disorder. It results from degenerative changes within the extrapyramidal motor system. Restless legs syndrome is another such disorder that can also be treated with cabergoline. In this case, the dopamine receptor agonist is used for symptomatic therapy. Other indications for cabergoline include hyperprolactinemia (excessively high prolactin levels) during pregnancy or breastfeeding, as well as weaning. In this process, the baby is weaned step by step from breast milk. Because cabergoline can cause pathological changes in the heart valves, the maximum recommended dose is limited to 3 milligrams daily.
Risks and side effects
When taking cabergoline, some unwanted side effects may occur.Because the drug is very often used together with levodopa, it is not always possible to say exactly whether the side effects are due to the drug itself or to the excess dopamine. The most common side effects include movement disorders, a compulsion to move, a drop in blood pressure when changing body position, dizziness, and changes in heart valves. Other negative side effects include sleep disturbances, severe fatigue, effusion of the pleura, angina attacks, pulmonary fibrosis (transformation of lung tissue), digestive problems, vomiting, edema of the limbs, inflammation of the stomach, headache, facial flushing, nerve insensitivity, confusion and delusions. If cabergoline is given for a short time during the first weaning to inhibit milk flow, a drop in blood pressure is possible. Abdominal pain, nausea, headache, and dizzy spells may also occur. If the patient exhibits behavioral abnormalities such as gambling, compulsive eating, compulsive spending of money, or an abnormal sexual urge, a change in therapy may be required. Cabergoline should not be administered at all if the patient is hypersensitive to the drug, suffers from changes in the heart valves, lung problems, an accumulation of fluid in the pleura, or if metabolic disorders such as eclampsia occur during pregnancy. Cabergoline is generally not approved for use in children. So far, there has been too little experience of treating them with the active substance. Therapy with cabergoline may also lead to interactions with other drugs. It is not advisable to take cabergoline together with other dopamine receptor agonists such as the antiemetic metoclopramide or neuroleptics, as these substances reduce the effectiveness of cabergoline. On the other hand, if the patient takes antifungals such as ketoconazole or macrolide antibiotics at the same time, this impedes the breakdown of the drug.
