Since cabergoline is not approved in the U.S. for Parkinsons Disease, but for hyperprolactinemia, the drug remains on the market. The lower doses required for treatment of hyperprolactinemia have been found to be not associated with clinically significant valvular heart disease or cardiac valve regurgitation. Interactions
No interactions were noted with levodopa or selegiline. The drug should not be combined with other ergot derivatives. Dopamine antagonists such as antipsychotics and metoclopramide counteract some effects of cabergoline. The use of antihypertensive drugs should be intensively monitored because excessive hypotension may result from the combination. Pharmacology
Pharmacodynamics
Cabergoline is a long-acting dopamine D2 receptor agonist. In-vitro rat studies show a direct inhibitory effect of cabergoline on the prolactin secretion in the lactotroph cells of the pituitary gland and cabergoline decreases serum prolactin levels in reserpinized rats. Although cabergoline is commonly described principally as a D2 receptor agonist, it also possesses significant affinity for the dopamine D3, and D4, serotonin 5-HT1A, 5-HT2A, 5-HT2B, and 5-HT2C, and α2-adrenergic receptors, as well as moderate/low affinity for the dopamine D1, serotonin 5-HT7, and α1-adrenergic receptors. Cabergoline functions as an partial or full agonist at all of these receptors except for the 5-HT7, α1-adrenergic, and α2-adrenergic receptors, where it acts as an antagonist. Cabergoline has been associated with cardiac valvulopathy due to activation of 5-HT2B receptors. Pharmacokinetics
Following a single oral dose, resorption of cabergoline from the gastrointestinal (GI) tract is highly variable, typically occurring within 0.5 to 4 hours. Ingestion with food does not alter its absorption rate.
Psychiatric disturbances and central nervous system (CNS): Altogether 51 percent of patients were affected. Very frequent: Sleep disturbances (somnolence 18%, insomnia 11%), vertigo (27%), and depression (13%). Frequent: dyskinesia (4%) and hallucinations (4%). Cardiovascular: Approximately 30 percent of patients experienced side effects. Most frequent were hypotension (10%), peripheral edema (14%) and non-specific edema (2%). Arrhythmias were encountered in 4.8%, palpitations in 4.3%, and angina pectoris in 1.4%.In a combination study with 2,000 patients also treated with levodopa, the incidence and severity of side effects was comparable to monotherapy. Encountered side effects required a termination of cabergoline treatment in 15% of patients. Additional side effects were infrequent cases of hematological side effects, and an occasional increase in liver enzymes or serum creatinine without signs or symptoms. As with other ergot derivatives, pleuritis, exudative pleura disease, pleura fibrosis, lung fibrosis, and pericarditis are seen. These side effects are noted in less than 2% of patients. They require immediate termination of treatment. Clinical improvement and normalization of X-ray findings are normally seen soon after cabergoline withdrawal. It appears that the dose typically used for treatment of hyperprolactinemia is too low to cause this type of side effects. Valvular heart disease
In two studies published in the New England Journal of Medicine on January 4, 2007, cabergoline was implicated along with pergolide in causing valvular heart disease. As a result of this, the FDA removed pergolide from the U.S. market on March 29, 2007.